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New submissions for Wed, 23 Apr 14

[1]  arXiv:1404.5298 [pdf, ps, other]
Title: ALFALFA Discovery of the Nearby Gas-rich Dwarf Galaxy Leo P. V. Neutral Gas Dynamics and Kinematics
Comments: 38 pages, 11 figures, Accepted for publication in the Astronomical Journal
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We present new HI spectral line imaging of the extremely metal-poor, star-forming dwarf irregular galaxy Leo P. Our HI images probe the global neutral gas properties and the local conditions of the interstellar medium (ISM). The HI morphology is slightly elongated along the optical major-axis. We do not find obvious signatures of interaction or infalling gas at large spatial scales. The neutral gas disk shows obvious rotation, although the velocity dispersion is comparable to the rotation velocity. The rotation amplitude is estimated to be V_c = 15 +/- 5 km/s. Within the HI radius probed by these observations, the mass ratio of gas to stars is roughly 2:1, while the ratio of the total mass to the baryonic mass is ~15:1. We use this information to place Leo P on the baryonic Tully-Fisher relation, testing the baryonic content of cosmic structures in a sparsely populated portion of parameter space that has hitherto been occupied primarily by dwarf spheroidal galaxies. We detect the signature of two temperature components in the neutral ISM of Leo P; the cold and warm components have characteristic velocity widths of 4.2 +/- 0.9 km/s and 10.1 +/- 1.2 km/s, corresponding to kinetic temperatures of ~1100 K and ~6200 K, respectively. The cold HI component is unresolved at a physical resolution of 200 pc. The highest HI surface densities are observed in close physical proximity to the single HII region. A comparison of the neutral gas properties of Leo P with other extremely metal-deficient (XMD) galaxies reveals that Leo P has the lowest neutral gas mass of any known XMD, and that the dynamical mass of Leo P is more than two orders of magnitude smaller than any known XMD with comparable metallicity.

[2]  arXiv:1404.5299 [pdf, ps, other]
Title: A Simple Technique for Predicting High-Redshift Galaxy Evolution
Comments: ApJ submitted
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We show that the ratio of galaxies' specific star formation rates (SSFRs) to their host halos' specific mass accretion rates (SMARs) strongly constrains how the galaxies' stellar masses, specific star formation rates, and host halo masses evolve over cosmic time. This evolutionary constraint provides a simple way to probe z>8 galaxy populations without direct observations. Tests of the method with galaxy properties at z=4 successfully reproduce the known evolution of the stellar mass--halo mass (SMHM) relation, galaxy SSFRs, and the cosmic star formation rate (CSFR) for 5<z<8. We then predict the continued evolution of these properties for 8<z<15. In contrast to the non-evolution in the SMHM relation at z<4, the median galaxy mass at fixed halo mass increases strongly at z>4. We show that this result is closely linked to the flattening in galaxy SSFRs at z>2 compared to halo specific mass accretion rates; we expect that average galaxy SSFRs at fixed stellar mass will continue their mild evolution to z~15. The expected CSFR shows no breaks or features at z>8.5; this constrains both reionization and the possibility of a steep falloff in the CSFR at z=9-10. Finally, we make predictions for the James Webb Space Telescope (JWST), which should be able to observe one galaxy with M* > ~10^8 Msun per 10^3 Mpc^3 at z=9.6 and one such galaxy per 10^4 Mpc^3 at z=15.

[3]  arXiv:1404.5301 [pdf, other]
Title: The properties of the cool circumgalactic gas probed with the SDSS, WISE and GALEX surveys
Comments: 14 pages, 11 figures, 1 table, submitted to ApJ, comments are welcome
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We explore the distribution of cool (~$10^4$K) gas around galaxies and its dependence on galaxy properties. By cross-correlating about 50,000 MgII absorbers with millions of sources from the SDSS (optical), WISE (IR), and GALEX (UV) surveys we effectively extract about 2,000 galaxy-absorber pairs at z~0.5 and probe relations between absorption strength and galaxy type, impact parameter and azimuthal angle. We find that cool gas traced by MgII absorbers exists around both star-forming and passive galaxies with a similar incidence rate on scales greater than 100 kpc but each galaxy type exhibits a different behavior on smaller scales: MgII equivalent width does not correlate with the presence of passive galaxies whereas stronger MgII absorbers tend to be found in the vicinity of star-forming galaxies. This effect is preferentially seen along the minor axis of these galaxies, suggesting that some of the gas is associated with outflowing material. In contrast, the distribution of cool gas around passive galaxies is consistent with being isotropic on the same scales. We quantify the average excess MgII equivalent width $<\delta W_{0}^{\rm MgII}>$ as a function of galaxy properties and find $<\delta W_0^{\rm MgII}>\propto SFR^{0.6}, sSFR^{0.4}$ and $M_\ast^{0.4}$ for star-forming galaxies. This work demonstrates that the dichotomy between star-forming and passive galaxies is reflected in the CGM traced by low-ionized gas. We also measure the covering fraction of MgII absorption and find it to be about 2-10 times higher for star-forming galaxies than passive ones within 50 kpc. We estimate the amount of neutral gas in the halo of $<\log M_\ast/{\rm M_\odot}>$~10.8 galaxies to be a few x$10^9 \rm M_\odot$ for both types of galaxies. Finally, we find that correlations between absorbers and sources detected in the UV and IR lead to physical trends consistent with those measured in the optical.

[4]  arXiv:1404.5302 [pdf, ps, other]
Title: The relation between gas density and velocity power spectra in galaxy clusters: high-resolution hydrodynamic simulations and the role of conduction
Comments: 15 pages, 10 figures; submitted to A&A - your comments are highly welcome
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); Fluid Dynamics (physics.flu-dyn)

Exploring the ICM power spectrum can help us to probe the physics of galaxy clusters. Using high-resolution 3D plasma simulations, we study the statistics of the velocity field and its relation with the thermodynamic perturbations. The normalization of the ICM spectrum (density, entropy, or pressure) is linearly tied to the level of large-scale motions, which excite both gravity and sound waves due to stratification. For low 3D Mach number M~0.25, gravity waves mainly drive entropy perturbations, traced by preferentially tangential turbulence. For M>0.5, sound waves start to significantly contribute, passing the leading role to compressive pressure fluctuations, associated with isotropic turbulence (or a slight radial bias). Density and temperature fluctuations are then characterized by the dominant process: isobaric (low M), adiabatic (high M), or isothermal (strong conduction). Most clusters reside in the intermediate regime, showing a mixture of gravity and sound waves, hence drifting towards isotropic velocities. Remarkably, regardless of the regime, the variance of density perturbations is comparable to the 1D Mach number. This linear relation allows to easily convert between gas motions and ICM perturbations, which can be exploited by Chandra, XMM data and by the forthcoming Astro-H. At intermediate and small scales (10-100 kpc), the turbulent velocities develop a Kolmogorov cascade. The thermodynamic perturbations act as effective tracers of the velocity field, broadly consistent with the Kolmogorov-Obukhov-Corrsin advection theory. Thermal conduction acts to damp the gas fluctuations, washing out the filamentary structures and steepening the spectrum, while leaving unaltered the velocity cascade. The ratio of the velocity and density spectrum thus inverts the downtrend shown by the non-diffusive models, allowing to probe the presence of significant conductivity in the ICM.

[5]  arXiv:1404.5305 [pdf, ps, other]
Title: Winds of low-metallicity OB-type stars: HST-COS spectroscopy in IC1613
Comments: ApJ, accepted. 50 pages, 13 figures
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

We present the first quantitative UV spectroscopic analysis of resolved OB stars in IC1613. Because of its alleged very low metallicity (<~1/10 Zo, from HII regions), studies in this Local Group dwarf galaxy could become a significant step forward from the SMC towards the extremely metal-poor massive stars of the early Universe. We present HST-COS data covering the ~1150-1800{\AA} wavelength range with resolution R~2500. We find that the targets do exhibit wind features, and these are similar in strength to SMC stars. Wind terminal velocities were derived from the observed PCygni profiles with the SEI method. The vinf-Z relationship has been revisited. The terminal velocity of IC1613 O-stars is clearly lower than Milky Way counterparts, but there is no clear difference between IC1613 and SMC or LMC analogue stars. We find no clear segregation with host galaxy in the terminal velocities of B-supergiants, nor in the vinf/vesc ratio of the whole OB star sample in any of the studied galaxies. Finally, we present first evidence that the Fe-abundance of IC1613 OB stars is similar to the SMC, in agreement with previous results on red supergiants. With the confirmed ~1/10 solar oxygen abundances of B-supergiants, our results indicate that IC1613's [alpha/Fe] ratio is sub-solar.

[6]  arXiv:1404.5306 [pdf, other]
Title: The relation between gas density and velocity power spectra in galaxy clusters: qualitative treatment and cosmological simulations
Authors: I. Zhuravleva (Stanford), E. Churazov (MPA, IKI), A. A. Schekochihin (Oxford), E. T. Lau (Yale), D. Nagai (Yale), M. Gaspari (MPA), S. W. Allen (Stanford, SLAC), K. Nelson (Yale), I. J. Parrish (CITA)
Comments: 6 pages, 3 figures, submitted to ApJ Letters
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)

We address the problem of evaluating the power spectrum of the velocity field of the ICM using only information on the plasma density fluctuations, which can be measured today by Chandra and XMM-Newton observatories. We argue that for relaxed clusters there is a linear relation between the rms density and velocity fluctuations across a range of scales, from the largest ones, where motions are dominated by buoyancy, down to small, turbulent scales: $(\delta\rho_k/\rho)^2 = \eta_1^2 (V_{1,k}/c_s)^2$, where $\delta\rho_k/\rho$ is the spectral amplitude of the density perturbations at wave number $k$, $V_{1,k}^2=V_k^2/3$ is the mean square component of the velocity field, $c_s$ is the sound speed, and $\eta_1$ is a dimensionless constant of order unity. Using cosmological simulations of relaxed galaxy clusters, we calibrate this relation and find $\eta_1\approx 1 \pm 0.3$. We argue that this value is set at large scales by buoyancy physics, while at small scales the density and velocity power spectra are proportional because the former are a passive scalar advected by the latter. This opens an interesting possibility to use gas density power spectra as a proxy for the velocity power spectra in relaxed clusters, across a wide range of scales.

[7]  arXiv:1404.5310 [pdf, ps, other]
Title: CMB with the background primordial magnetic field
Authors: Dai G. Yamazaki
Comments: 14 pages, 5 figures
Journal-ref: Phys. Rev. D 89, 083528(2014)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)

We investigate the effects of the background primordial magnetic field (PMF) on the cosmic microwave background (CMB). The sound speed of the tightly coupled photon-baryon fluid is increased by the background PMF. The increased sound speed causes the odd peaks of the CMB temperature fluctuations to be suppressed and the CMB peak positions to be shifted to a larger scale. The background PMF causes a stronger decaying potential and increases the amplitude of the CMB. These two effects of the background PMF on a smaller scale cancel out, and the overall effects of the background PMF are the suppression of the CMB around the first peak and the shifting of peaks to a large scale. We also discuss obtaining information about the PMF generation mechanisms, and we examine the nonlinear evolution of the PMF by the constraint on the maximum scale for the PMF distributions. Finally, we discuss degeneracies between the PMF parameters and the standard cosmological parameters.

[8]  arXiv:1404.5311 [pdf, other]
Title: Multi-frequency radiation hydrodynamics simulations of H2 line emission in primordial, star-forming clouds
Authors: Thomas H. Greif
Comments: 18 pages, 1 table, 9 figures, submitted to MNRAS
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We investigate the collapse of primordial gas in a minihalo with three-dimensional radiation hydrodynamics simulations that accurately model the transfer of H2 line emission. For this purpose, we have implemented a multi-line, multi-frequency ray-tracing scheme in the moving-mesh code Arepo that is capable of adaptively refining rays based on the Healpix algorithm, as well as a hybrid equilibrium/non-equilibrium primordial chemistry solver. We find that the chemical and thermal evolution of the central gas cloud is similar to the case where an escape probability formalism with a fit to detailed one-dimensional calculations is used, with the exception that the suppression of density perturbations due to the diffusion of radiation is only present in the full radiation hydrodynamics simulations. A multi-frequency treatment of the individual H2 lines is essential, since for high optical depths the smaller cross section in the wings of the lines greatly increases the amount of energy that can escape. The influence of Doppler shifts due to bulk velocities is comparatively small, since systematic velocity differences in the cloud are typically smaller than the sound speed. The radially averaged escape fraction agrees well with the fit of Ripamonti & Abel 2004, while for high optical depths the Sobolev method overestimates the escape fraction by more than an order of magnitude. This is due to the violation of the Sobolev condition, which states that the Sobolev length must be much smaller than the scale on which the properties of the gas change. The resulting discrepancy in the escape fraction explains the differences between primordial gas clouds found in previous studies.

[9]  arXiv:1404.5312 [pdf, other]
Title: Constraining galaxy cluster temperatures and redshifts with eROSITA survey data
Comments: accepted for publication in A&A; 17 pages, 20 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

The nature of dark energy is imprinted in the large-scale structure of the Universe and thus in the mass and redshift distribution of galaxy clusters. The upcoming eROSITA mission will exploit this method of probing dark energy by detecting roughly 100,000 clusters of galaxies in X-rays. For a precise cosmological analysis the various galaxy cluster properties need to be measured with high precision and accuracy. To predict these characteristics of eROSITA galaxy clusters and to optimise optical follow-up observations, we estimate the precision and the accuracy with which eROSITA will be able to determine galaxy cluster temperatures and redshifts from X-ray spectra. Additionally, we present the total number of clusters for which these two properties will be available from the eROSITA survey directly. During its four years of all-sky surveys, eROSITA will determine cluster temperatures with relative uncertainties of Delta(T)/T<10% at the 68%-confidence level for clusters up to redshifts of z~0.16 which corresponds to ~1,670 new clusters with precise properties. Redshift information itself will become available with a precision of Delta(z)/(1+z)<10% for clusters up to z~0.45. Additionally, we estimate how the number of clusters with precise properties increases with a deepening of the exposure. Furthermore, the biases in the best-fit temperatures as well as in the estimated uncertainties are quantified and shown to be negligible in the relevant parameter range in general. For the remaining parameter sets, we provide correction functions and factors. The eROSITA survey will increase the number of galaxy clusters with precise temperature measurements by a factor of 5-10. Thus the instrument presents itself as a powerful tool for the determination of tight constraints on the cosmological parameters.

[10]  arXiv:1404.5313 [pdf, other]
Title: Too Big to Fail in the Local Group
Comments: 16 pages, 14 figures, 2 tables, submitted to MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We compare the dynamical masses of dwarf galaxies in the Local Group (LG) to the predicted masses of halos in the ELVIS suite of $\Lambda$CDM simulations, a sample of 48 Galaxy-size hosts, 24 of which are in paired configuration similar to the LG. We enumerate unaccounted-for dense halos ($V_\mathrm{max} \gtrsim 25$ km s$^{-1}$) in these volumes that at some point in their histories were massive enough to have formed stars in the presence of an ionizing background ($V_\mathrm{peak} > 30$ km s$^{-1}$). Within 300 kpc of the Milky Way, the number of unaccounted-for massive halos ranges from 2 - 25 over our full sample. Moreover, this "too big to fail" count grows as we extend our comparison to the outer regions of the Local Group: within 1.2 Mpc of either giant we find that there are 12-40 unaccounted-for massive halos. This count excludes volumes within 300 kpc of both the MW and M31, and thus should be largely unaffected by any baryonically-induced environmental processes. According to abundance matching -- specifically abundance matching that reproduces the Local Group stellar mass function -- all of these missing massive systems should have been quite bright, with $M_\star > 10^6M_\odot$. Finally, we use the predicted density structure of outer LG dark matter halos together with observed dwarf galaxy masses to derive an $M_\star-V_\mathrm{max}$ relation for LG galaxies that are outside the virial regions of either giant. We find that there is no obvious trend in the relation over three orders of magnitude in stellar mass (a "common mass" relation), from $M_\star \sim 10^8 - 10^5 M_\odot$, in drastic conflict with the tight relation expected for halos that are unaffected by reionization. Solutions to the too big to fail problem that rely on ram pressure stripping, tidal effects, or statistical flukes appear less likely in the face of these results.

[11]  arXiv:1404.5315 [pdf, other]
Title: AGN Feedback in the Hot Halo of NGC 4649
Comments: 23 pages, 10 figures, 3 tables. Accepted for publication on ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)

Using the deepest available $\textit{Chandra}$ observations of NGC 4649 we find strong evidences of cavities, ripples and ring like structures in the hot interstellar medium (ISM) that appear to be morphologically related with the central radio emission. These structures show no significant temperature variations in correspondence with higher pressure regions ($0.5\mbox{kpc}<r<3\mbox{kpc}$). On the same spatial scale, a discrepancy between the mass profiles obtained from stellar dynamic and $\textit{Chandra}$ data represents the telltale evidence of a significant non-thermal pressure component in this hot gas, which is related to the radio jet and lobes. On larger scale we find agreement between the mass profile obtained form $\textit{Chandra}$ data and planetary nebulae and globular cluster dynamics. The nucleus of NGC 4649 appears to be extremely radiatively inefficient, with highly sub-Bondi accretion flow. Consistently with this finding, the jet power evaluated from the observed X-ray cavities implies that a small fraction of the accretion power calculated for the Bondi mass accretion rate emerges as kinetic energy. Comparing the jet power to radio and nuclear X-ray luminosity the observed cavities show similar behavior to those of other giant elliptical galaxies.

[12]  arXiv:1404.5316 [pdf, ps, other]
Title: Different X-ray spectral evolution for black hole X-ray binaries in dual tracks of radio-X-ray correlation
Authors: Xiao-Feng Cao (HUST), Qingwen Wu (Huazhong Univ of Sci and Tech), Ai-Jun Dong (HUST)
Comments: Accepted for publication in ApJ; 10 pages, 5 figures, 5 tables
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Recently an `outliers' track of radio-X-ray correlation was found, which is much steeper than the former universal correlation, where dual tracks were speculated to be triggered by different accretion processes. In this work, we test this issue by exploring hard X-ray spectral evolution in four black-hole X-ray binaries (XRBs) with multiple, quasi-simultaneous radio and X-ray observations. Firstly, we find that hard X-ray photon indices, $\Gamma$, are anti- and positively correlated to X-ray fluxes when the X-ray flux, $F_{\rm 3-9keV}$, is below and above a critical flux, $F_{\rm X,crit}$, which are consistent with prediction of advection dominated accretion flow (ADAF) and disk-corona model respectively. Secondly and most importantly, we find that the radio-X-ray correlations are also clearly different when the X-ray fluxes are higher and lower than the critical flux that defined by X-ray spectral evolution. The data points with $F_{\rm 3-9keV}\gtrsim F_{\rm X,crit}$ have a steeper radio-X-ray correlation ($F_{\rm X}\propto F_{\rm R}^{b}$ and $b\sim 1.1-1.4$), which roughly form the `outliers' track. However, the data points with anti-correlation of $\Gamma-F_{\rm 3-9keV}$ either stay in the universal track with $b\sim0.61$ or stay in transition track (from the universal to `outliers' tracks or vice versa). Therefore, our results support that the universal and `outliers' tracks of radio-X-ray correlations are regulated by radiatively inefficient and radiatively efficient accretion model respectively.

[13]  arXiv:1404.5317 [pdf, ps, other]
Title: A new fundamental plane for radiatively efficient black-hole sources
Authors: Ai-Jun Dong (HUST), Qingwen Wu (Huazhong Univ of Sci and Tech), Xiao-Feng Cao (HUST)
Comments: Accepted for publication in ApJ Letter; emulateapj format; 6 pages, 3 figures, 1 table
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

In recent years, it was found that there are several low/hard state of X-ray binaries (XRBs) follow an `outliers' track of radio--X-ray correlation ($L_{\rm R}\propto L_{\rm X}^{b}$ and $b\sim1.4$), which is much steeper than the former universal track with $b\sim0.6$. In this work, we compile a sample of bright radio-quiet active galactic nuclei (AGNs) and find that their hard X-ray photon indices and Eddington ratios are positively correlated, which is similar to that of `outliers' of XRBs, where both bright AGNs and `outliers' of XRBs have bolometric Eddington ratios $\gtrsim1%L_{\rm Edd}$ ($L_{\rm Edd}$ is Eddington luminosity). The Eddington-scaled radio--X-ray correlation of these AGNs is also similar to that of `outliers' of XRBs, which has a form of $L_{\rm 5 GHz}/L_{\rm Edd}\propto (L_{\rm 2-10 keV}/L_{\rm Edd})^{c}$ with $c\simeq1.59$ and 1.53 for AGNs and XRBs respectively. Both the positively correlated X-ray spectral evolution and the steeper radio--X-ray correlation can be regulated by a radiatively efficient accretion flow (e.g., disk-corona). Based on these similarities, we further present a new fundamental plane for `outliers' of XRBs and bright AGNs in black-hole (BH) mass, radio and X-ray luminosity space: $\log L_{\rm R}=1.59^{+0.28}_{-0.22} \log L_{\rm X}- 0.22^{+0.19}_{-0.20}\log M_{\rm BH}-28.97^{+0.45}_{-0.45}$ with a scatter of $\sigma_{\rm R}=0.51\rm dex$. This fundamental plane is suitable for radiatively efficient BH sources, while the former plane proposed by Merloni et al. and Falcke et al. may be most suitable for radiatively inefficient sources.

[14]  arXiv:1404.5319 [pdf, other]
Title: Photospheric emission from long duration gamma-ray bursts powered by variable engines
Authors: Diego López-Cámara (NCSU), Brian Morsony (UWi, Madison), Davide Lazzati (NCSU, Oregon State)
Comments: 7 pages, 6 figures, submitted to MNRAS
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We present the results of a set of numerical simulations of long-duration gamma-ray burst jets aimed at studying the effect of a variable engine on the peak frequency of the photospheric emission. Our simulations follow the propagation of the jet inside the progenitor star, its break-out, and the subsequent expansion in the environment out to the photospheric radius. A constant and two step-function models are considered for the engine luminosity. We show that our synthetic light-curves follow a luminosity-peak frequency correlation analogous to the Golenetskii correlation found in long-duration gamma-ray burst observations. Within the parameter space explored, it appears that the central engine luminosity profile does not have a significant effect on the location of a gamma-ray burst in the Luminosity-peak frequency plane, bursts from different central engines being indistinguishable from each other.

[15]  arXiv:1404.5323 [pdf, ps, other]
Title: Spatial variations in the spectral index of polarized synchrotron emission in the 9-year WMAP sky maps
Comments: 10 pages, 9 figures, submitted to ApJ
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We estimate the spectral index, $\beta$, of polarized synchrotron emission as observed in the 9-year WMAP sky maps using two different methods, both linear regression ("T--T plot") and maximum likelihood. We partition the sky into 24 disjoint sky regions, and evaluate the spectral index for all polarization angles between 0 and $85^{\circ}$ in steps of $5^{\circ}$. Averaging over polarization angles, we derive a mean spectral index of $\beta^{all-sky} =-2.99\pm0.01$. Considering the Galactic plane and high latitude regions separately, we find that the synchrotron spectral index steepens by $\sim0.15$ from low to high latitudes, in agreement with previous studies, with mean spectral indices of $\beta^{plane} = -2.98\pm0.01$ and $\beta^{high-lat} = -3.12\pm0.04$, respectively. In addition, we find a significant longitudinal spectral index variation along the Galactic plane that is well modelled by an offset sinusoidal, $\beta(l) = -2.85 + 0.17\sin(2l - 90^{\circ})$. Finally, we study synchrotron emission in the BICEP2 field, in an attempt to understand whether the recently claimed detection of large-scale B-mode polarization could be explained in terms of synchrotron contamination. We estimate that the standard deviation of synchrotron emission in this field is $2.4\,\mu K$ at K-band on the angular scales of interest. Adopting a spectral index of $\beta=-3.12$, typical for high Galactic latitudes, this corresponds to a synchrotron amplitude of 0.011$\mu K$ at 150 GHz, equivalent to a primordial B-mode signal of $r=0.003$. The flattest index allowed by the data in this very low signal to noise region is $\beta=-2.5$, for which the projected amplitude is 0.036$\,\mu K$. Thus, under the assumption of a straight power-law frequency spectrum, we find that synchrotron emission can in the absolutely worst-case scenario account for at most 20% of the reported BICEP2 signal.

[16]  arXiv:1404.5335 [pdf, ps, other]
Title: An Analysis of the SEEDS High-Contrast Exoplanet Survey: Massive Planets or Low-Mass Brown Dwarfs?
Comments: 21 pages, 5 figures, submitted to ApJ
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)

We conduct a statistical analysis of a combined sample of direct imaging data, totalling nearly 250 stars observed by HiCIAO on the Subaru Telescope, NIRI on Gemini North, and NICI on Gemini South. The stars cover a wide range of ages and spectral types, and include five detections (kap And b, two ~60 M_J brown dwarf companions in the Pleiades, PZ Tel B, and CD-35 2722 B). We conduct a uniform, Bayesian analysis of the ages of our entire sample, using both membership in a kinematic moving group and activity/rotation age indicators, to obtain posterior age distributions. We then present a new statistical method for computing the likelihood of a substellar distribution function. By performing most integrals analytically, we achieve an enormous speedup over brute-force Monte Carlo. We use this method to place upper limits on the maximum semimajor axis beyond which the distribution function for radial-velocity planets cannot extend, finding model-dependent values of ~30--100 AU. Finally, we treat our entire substellar sample together, modeling it as a single power law distribution. After including GJ 758 B and GJ 504 b, two other HiCIAO detections, a distribution $p(M, a) \propto M^{-0.7 \pm 0.6} a^{-0.8 \pm 0.4}$ (1 sigma errors) from massive brown dwarfs to a theoretically motivated cutoff at ~5 M_J, provides an adequate fit to our data. This suggests that many of the directly imaged exoplanets known, including most (if not all) of the low-mass companions in our sample, formed by fragmentation in a cloud or disk, and represent the low-mass tail of the brown dwarfs.

[17]  arXiv:1404.5336 [pdf, other]
Title: X-rays from Magnetically Confined Wind Shocks: Effect of Cooling-Regulated Shock Retreat
Comments: Accepted for publication in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We use 2D MHD simulations to examine the effects of radiative cooling and inverse Compton (IC) cooling on X-ray emission from magnetically confined wind shocks (MCWS) in magnetic massive stars with radiatively driven stellar winds. For the standard dependence of mass loss rate on luminosity $\Mdot \sim L^{1.7} $, the scaling of IC cooling with $L$ and radiative cooling with $\Mdot$ means that IC cooling become formally more important for lower luminosity stars. However, because the sense of the trends is similar, we find the overall effect of including IC cooling is quite modest. More significantly, for stars with high enough mass loss to keep the shocks radiative, the MHD simulations indicate a linear scaling of X-ray luminosity with mass loss rate; but for lower luminosity stars with weak winds, X-ray emission is reduced and softened by a {\em shock retreat} resulting from the larger post-shock cooling length, which within the fixed length of a closed magnetic loop forces the shock back to lower pre-shock wind speeds. A semi-analytic scaling analysis that accounts both for the wind magnetic confinement and this shock retreat yields X-ray luminosities that have a similar scaling trend, but a factor few higher values, compared to time-averages computed from the MHD simulations. The simulation and scaling results here thus provide a good basis for interpreting available X-ray observations from the growing list of massive stars with confirmed large-scale magnetic fields.

[18]  arXiv:1404.5337 [pdf, other]
Title: Prospects for Detecting Oxygen, Water, and Chlorophyll in an Exo-Earth
Comments: 6 pages, 6 figures, submitted to PNAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)

The goal of finding and characterizing nearby Earth-like planets is driving many NASA high-contrast flagship mission concepts, the latest of which is known as the Advanced Technology Large-Aperture Space Telescope (ATLAST). In this article, we calculate the optimal spectral resolution $R=\lambda/\delta\lambda$ and minimum signal-to-noise ratio per spectral bin (SNR), two central design requirements for a high-contrast space mission, in order to detect signatures of water, oxygen, and chlorophyll on an Earth twin. We first develop a minimally parametric model and demonstrate its ability to fit model Earth spectra; this allows us to measure the statistical evidence for each component's presence. We find that water is the most straightforward to detect, requiring a resolving power R>~20, while the optimal resolving power for oxygen is likely to be closer to R=150, somewhat higher than the canonical value in the literature. At these resolutions, detecting oxygen will require ~3 times the SNR as water. Chlorophyll, should it also be used by alien plants in photosynthesis, requires ~6 times the SNR as oxygen for an Earth twin, only falling to oxygen-like levels of detectability for a very low cloud cover and/or a very large vegetation covering fraction. This suggests designing a mission for sensitivity to oxygen and adopting a multi-tiered observing strategy, first targeting water, then oxygen on the more favorable planets, and finally chlorophyll on only the most promising worlds.

[19]  arXiv:1404.5338 [pdf, other]
Title: The HNC/HCN Ratio in Star-Forming Regions
Comments: 14 pages, 11 figures, Accepted for publication in ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA)

HNC and HCN, typically used as dense gas tracers in molecular clouds, are a pair of isomers that have great potential as a temperature probe because of temperature dependent, isomer-specific formation and destruction pathways. Previous observations of the HNC/HCN abundance ratio show that the ratio decreases with increasing temperature, something that standard astrochemical models cannot reproduce. We have undertaken a detailed parameter study on which environmental characteristics and chemical reactions affect the HNC/HCN ratio and can thus contribute to the observed dependence. Using existing gas and gas-grain models updated with new reactions and reaction barriers, we find that in static models the H + HNC gas-phase reaction regulates the HNC/HCN ratio under all conditions, except for very early times. We quantitively constrain the combinations of H abundance and H + HNC reaction barrier that can explain the observed HNC/HCN temperature dependence and discuss the implications in light of new quantum chemical calculations. In warm-up models, gas-grain chemistry contributes significantly to the predicted HNC/HCN ratio and understanding the dynamics of star formation is therefore key to model the HNC/HCN system.

[20]  arXiv:1404.5354 [pdf, ps, other]
Title: A New Method for Measuring Metallicities of Young Super Star Clusters
Comments: 6 pages, 6 figures. Accepted for publication in ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We demonstrate how the metallicities of young super star clusters can be measured using novel spectroscopic techniques in the J-band. The near-infrared flux of super star clusters older than ~6 Myr is dominated by tens to hundreds of red supergiant stars. Our technique is designed to harness the integrated light of that population and produces accurate metallicities for new observations in galaxies above (M83) and below (NGC 6946) solar metallicity. In M83 we find [Z]= +0.28 +/- 0.14 dex using a moderate resolution (R~3500) J-band spectrum and in NGC 6496 we report [Z]= -0.32 +/- 0.20 dex from a low resolution spectrum of R~1800. Recently commissioned low resolution multiplexed spectrographs on the VLT (KMOS) and Keck (MOSFIRE) will allow accurate measurements of super star cluster metallicities across the disks of star-forming galaxies up to distances of 70 Mpc with single night observation campaigns using the method presented in this letter.

[21]  arXiv:1404.5355 [pdf, other]
Title: Identification of Two Radio Loud Narrow Line Seyfert 1 Galaxies at Gamma-Ray Energies
Comments: 18 pages, 3 tables, 2 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We report the discovery of gamma-ray emission from two radio-loud narrow-line Seyfert 1 galaxies using data from Fermi/LAT: J0804+3853 (z = 0.211) and J1443+4725 (z = 0.502). The objects were discovered due to singular, separate, and brief brightening events of a few months' duration during the first 66 months of Fermi observations. Also presented are our efforts thus far to monitor the optical photopolarimetric variability of these targets. This work brings the total number of this class identified at gamma-ray energies from seven to nine, thus representing a significant increase in this population of AGN. These findings can have strong implications with regard to our understanding of systems with relativistic jets.

[22]  arXiv:1404.5360 [pdf, other]
Title: Planets Transiting Non-Eclipsing Binaries
Comments: 19 pages, 14 figures, submitted November 2013 to A&A
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

The majority of binary stars do not eclipse. Current searches for transiting circumbinary planets concentrate on eclipsing binaries, and are therefore restricted to a small fraction of potential hosts. We investigate the concept of finding planets transiting non-eclipsing binaries, whose geometry would require mutually inclined planes. Using an N-body code we explore how the number and sequence of transits vary as functions of observing time and orbital parameters. The concept is then generalised thanks to a suite of simulated circumbinary systems. Binaries are constructed from radial-velocity surveys of the solar neighbourhood. They are then populated with orbiting gas giants, drawn from a range of distributions. The binary population is shown to be compatible with the Kepler eclipsing binary catalogue, indicating that the properties of binaries may be as universal as the initial mass function. These synthetic systems produce transiting circumbinary planets on both eclipsing and non-eclipsing binaries. Simulated planets transiting eclipsing binaries are compared with published Kepler detections. We obtain 1) that planets transiting non-eclipsing binaries probably exist in the Kepler data, 2) that observational biases alone cannot account for the observed over-density of circumbi- nary planets near the stability limit, implying a physical pile-up, and 3) that the distributions of gas giants orbiting single and binary stars are likely different. Estimating the frequency of circumbinary planets is degenerate with the spread in mutual inclination. Only a minimum occurrence rate can be produced, which we find to be compatible with 9%. Searching for inclined circumbinary planets may significantly increase the population of known objects and will test our conclusions. Their existence, or absence, will reveal the true occurrence rate and help develop circumbinary planet formation theories.

[23]  arXiv:1404.5369 [pdf, ps, other]
Title: Observational discrimination of Eddington-inspired Born-Infeld gravity from general relativity
Authors: Hajime Sotani
Comments: accepted for publication in PRD
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)

Direct observations of neutron stars could tell us an imprint of modified gravity. However, it is generally difficult to resolve the degeneracy due to the uncertainties in equation of state (EOS) of neutron star matter and in gravitational theories. In this paper, we are successful to find the observational possibility to distinguish Eddington-inspired Born-Infeld gravity (EiBI) from general relativity. We show that the radii of neutron stars with $0.5M_{sun}$ are strongly correlated with the neutron skin thickness of ${}^{208}$Pb independently of EOS, while this correlation depends on the coupling constant in EiBI. As a result, via the direct observations of radius of neutron star with $0.5M_{sun}$ and the measurements of neutron skin thickness of ${}^{208}$Pb by the terrestrial experiments, one could not only discriminate EiBI from general relativity but also estimate the coupling constant in EiBI.

[24]  arXiv:1404.5377 [pdf, ps, other]
Title: Radial Velocities of Stars with Multiple Co-orbital Planets
Comments: 16 pages, 3 figures, 1 table
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

To date, well over a thousand planets have been discovered orbiting other stars, hundreds of them in multi-planet systems. Most of these exoplanets have been detected by either the transit method or the radial velocity method, rather than by other methods such as astrometry or direct imaging. Both the radial velocity and astrometric methods rely upon the reflex motion of the parent star induced by the gravitational attraction of its planets. However, this reflex motion is subject to misinterpretation when a star has two or more planets with the same orbital period. Such co-orbital planets may effectively "hide" from detection by current algorithms.
In principle, any number of planets can share the same orbit; the case where they all have the same mass has been studied most. Salo and Yoder (A & A 205, 309--327, 1988) have shown that more than 8 planets of equal mass sharing a circular orbit must be equally spaced for dynamical stability, while fewer than 7 equal-mass planets are stable only in a configuration where all of the planets remain on the same side of their parent star. For 7 or 8 equal-mass planets, both configurations are stable.
By symmetry, it is clear that the equally-spaced systems produce no reflex motion or radial velocity signal at all in their parent stars. This could lead to their being overlooked entirely, unless they happen to be detected by the transit method. It is equally clear that the lopsided systems produce a greater radial velocity signal than a single such planet would, but a smaller signal than if all of the planets were combined into one. This could seriously mislead estimates of exoplanet masses and densities. Transit data and ellipsoidal (tidal) brightness variations in such systems also are subject to misinterpretation. This behavior is also representative of more natural systems, with co-orbital planets of different masses.

[25]  arXiv:1404.5391 [pdf, ps, other]
Title: Dust Production Factories in the Early Universe: Formation of Carbon Grains in Red-supergiant Winds of Very Massive Population III Stars
Comments: 1 table, 4 figures, accepted for publication in the ApJ Letters
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We investigate the formation of dust in a stellar wind during the red-supergiant (RSG) phase of a very massive Population III star with the zero-age main sequence mass of 500 M_sun. We show that, in a carbon-rich wind with a constant velocity, carbon grains can form with a lognormal-like size distribution, and that all of the carbon available for dust formation finally condense into dust for wide ranges of the mass-loss rate ((0.1-3)x10^{-3} M_sun yr^{-1}) and wind velocity (1-100 km s^{-1}). We also find that the acceleration of the wind driven by newly formed dust suppresses the grain growth but still allows more than half of gas-phase carbon to be finally locked up in dust grains. These results indicate that at most 1.7 M_sun of carbon grains can form in total during the RSG phase of 500 M_sun Population III stars. Such a high dust yield could place very massive primordial stars as important sources of dust at the very early epoch of the universe if the initial mass function of Population III stars was top-heavy. We also briefly discuss a new formation scenario of carbon-rich ultra-metal-poor stars considering the feedback from very massive Population III stars.

[26]  arXiv:1404.5407 [pdf, other]
Title: Quantifying the impact of future Sandage-Loeb test data on dark energy constraints
Comments: 5 pages, 3 figures, 1 table
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)

The Sandage-Loeb (SL) test is a unique method to probe dark energy in the "redshift desert" of $2\lesssim z\lesssim 5$, and thus it provides an important supplement to the other dark energy probes. Therefore, it is of great importance to quantify how the future SL test data impact on the dark energy constraints. To avoid the potential inconsistency in data, we use the best-fitting model based on the other geometric measurements as the fiducial model to produce 30 mock SL test data. The 10-yr, 20-yr, and 30-yr observations of SL test are analyzed and compared in detail. We show that compared to the current combined data of type Ia supernovae, baryon acoustic oscillation, cosmic microwave background, and Hubble constant, the 30-yr observation of SL test could improve the constraint on $\Omega_m$ by about $80%$ and the constraint on $w$ by about $25%$. Furthermore, the SL test can also improve the measurement of the possible direct interaction between dark energy and dark matter. We show that the SL test 30-yr data could improve the constraint on $\gamma$ by about $30%$ and $10%$ for the $Q=\gamma H\rho_c$ and $Q=\gamma H\rho_{de}$ models, respectively.

[27]  arXiv:1404.5415 [pdf, ps, other]
Title: Results from the Wilkinson Microwave Anisotropy Probe
Comments: 24 pages, 7 figures, invited review for Special Section "CMB Cosmology" of Progress of Theoretical and Experimental Physics (PTEP)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

The Wilkinson Microwave Anisotropy Probe (WMAP) mapped the distribution of temperature and polarization over the entire sky in five microwave frequency bands. These full-sky maps were used to obtain measurements of temperature and polarization anisotropy of the cosmic microwave background with the unprecedented accuracy and precision. The analysis of two-point correlation functions of temperature and polarization data gives determinations of the fundamental cosmological parameters such as the age and composition of the universe, as well as the key parameters describing the physics of inflation, which is further constrained by three-point correlation functions. WMAP observations alone reduced the flat $\Lambda$ cold dark matter ($\Lambda$CDM) cosmological model (six) parameter volume by a factor of >68,000 compared with pre-WMAP measurements. The WMAP observations (sometimes in combination with other astrophysical probes) convincingly show the existence of non-baryonic dark matter, the cosmic neutrino background, flatness of spatial geometry of the universe, a deviation from a scale-invariant spectrum of initial scalar fluctuations, and that the current universe is undergoing an accelerated expansion. The WMAP observations provide the strongest ever support for inflation; namely, the structures we see in the universe originate from quantum fluctuations generated during inflation.

[28]  arXiv:1404.5434 [pdf, ps, other]
Title: The many sides of RCW 86: a type Ia supernova remnant evolving in its progenitor's wind bubble
Comments: Accepted for publication in MNRAS. 16 pages, 13 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We present the results of a detailed investigation of the Galactic supernova remnant RCW 86 using the XMM-Newton X-ray telescope. RCW 86 is the probable remnant of SN 185 A.D, a supernova that likely exploded inside a wind-blown cavity. We use the XMM-Newton Reflection Grating Spectrometer (RGS) to derive precise temperatures and ionization ages of the plasma, which are an indication of the interaction history of the remnant with the presumed cavity. We find that the spectra are well fitted by two non-equilibrium ionization models, which enables us to constrain the properties of the ejecta and interstellar matter plasma. Furthermore, we performed a principal component analysis on EPIC MOS and pn data to find regions with particular spectral properties. We present evidence that the shocked ejecta, emitting Fe-K and Si line emission, are confined to a shell of approximately 2 pc width with an oblate spheroidal morphology. Using detailed hydrodynamical simulations, we show that general dynamical and emission properties at different portions of the remnant can be well-reproduced by a type Ia supernova that exploded in a non-spherically symmetric wind-blown cavity. We also show that this cavity can be created using general wind properties for a single degenerate system. Our data and simulations provide further evidence that RCW 86 is indeed the remnant of SN 185, and is the likely result of a type Ia explosion of single degenerate origin.

[29]  arXiv:1404.5462 [pdf, ps, other]
Title: Planet Traps and First Planets: the Critical Metallicity for Gas Giant Formation
Comments: 10 pages, 3 figures, 5 tables, accepted for publication in ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

The ubiquity of planets poses an interesting question: when first planets are formed in galaxies. We investigate this problem by adopting a theoretical model developed for understanding the statistical properties of exoplanets. Our model is constructed as the combination of planet traps with the standard core accretion scenario in which the efficiency of forming planetary cores directly relates to the dust density in disks or the metallicity ([Fe/H]). We statistically compute planet formation frequencies (PFFs) as well as the orbital radius ($<R_{rapid}>$) within which gas accretion becomes efficient enough to form Jovian planets. The three characteristic exoplanetary populations are considered: hot Jupiters, exo-Jupiters densely populated around 1 AU, and low-mass planets such as super-Earths. We explore the behavior of the PFFs as well as $<R_{rapid}>$ for the three different populations as a function of metallicity ($-2 \leq$[Fe/H]$\leq -0.6$). We show that the total PFFs increase steadily with metallicity, which is the direct outcome of the core accretion picture. For the entire range of the metallicity considered here, the population of the low-mass planets dominates over the Jovian planets. The Jovian planets contribute to the PFFs above [Fe/H]-1. We find that the hot Jupiters form at lower metallcities than the exo-Jupiters. This arises from the radially inward transport of planetary cores by their host traps, which is more effective for lower metallicity disks due to the slower growth of the cores. The PFFs for the exo-Jupiters exceed those for the hot Jupiters around [Fe/H]-0.7. Finally, we show that the critical metallicity for forming Jovian planets is [Fe/H]-1.2, which is evaluated by comparing the values of $<R_{rapid}>$ between the hot Jupiters and the low-mass planets. The comparison intrinsically links to the different gas accretion efficiency between them.

[30]  arXiv:1404.5463 [pdf, other]
Title: Collective outflow from a small multiple stellar system
Comments: ApJ in press, movies: this http URL
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

The formation of high-mass stars is usually accompanied by powerful protostellar outflows. Such high-mass outflows are not simply scaled-up versions of their lower-mass counterparts, since observations suggest that the collimation degree degrades with stellar mass. Theoretically, the origins of massive outflows remain open to question because radiative feedback and fragmentation of the accretion flow around the most massive stars, with M > 15 M_Sun, may impede the driving of magnetic disk winds. We here present a three-dimensional simulation of the early stages of core fragmentation and massive star formation that includes a subgrid-scale model for protostellar outflows. We find that stars that form in a common accretion flow tend to have aligned outflow axes, so that the individual jets of multiple stars can combine to form a collective outflow. We compare our simulation to observations with synthetic H_2 and CO observations and find that the morphology and kinematics of such a collective outflow resembles some observed massive outflows, such as Cepheus A and DR 21. We finally compare physical quantities derived from simulated observations of our models to the actual values in the models to examine the reliability of standard methods for deriving physical quantities, demonstrating that those methods indeed recover the actual values to within a factor of 2-3.

[31]  arXiv:1404.5464 [pdf, ps, other]
Title: Monte Carlo simulations of post-common-envelope white dwarf + main sequence binaries: comparison with the SDSS DR7 observed sample
Comments: 15 pages, 7 figures, accepted for publication in A&A
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

Detached white dwarf + main sequence (WD+MS) systems represent the simplest population of post-common envelope binaries (PCEBs). Since the ensemble properties of this population carries important information about the characteristics of the common-envelope (CE) phase, it deserves close scrutiny. However, most population synthesis studies do not fully take into account the effects of the observational selection biases of the samples used to compare with the theoretical simulations. Here we present the results of a set of detailed Monte Carlo simulations of the population of WD+MS binaries in the Sloan Digital Sky Survey (SDSS) Data Release 7. We used up-to-date stellar evolutionary models, a complete treatment of the Roche lobe overflow episode, and a full implementation of the orbital evolution of the binary systems. Moreover, in our treatment we took into account the selection criteria and all the known observational biases. Our population synthesis study allowed us to make a meaningful comparison with the available observational data. In particular, we examined the CE efficiency, the possible contribution of internal energy, and the initial mass ratio distribution (IMRD) of the binary systems. We found that our simulations correctly reproduce the properties of the observed distribution of WD+MS PCEBs. In particular, we found that once the observational biases are carefully taken into account, the distribution of orbital periods and of masses of the WD and MS stars can be correctly reproduced for several choices of the free parameters and different IMRDs, although models in which a moderate fraction (<=10%) of the internal energy is used to eject the CE and in which a low value of CE efficiency is used (<=0.3) seem to fit better the observational data. We also found that systems with He-core WDs are over-represented in the observed sample, due to selection effects.

[32]  arXiv:1404.5469 [pdf, ps, other]
Title: CFHTLenS: Cosmological constraints from a combination of cosmic shear two-point and three-point correlations
Comments: Accepted by MNRAS. 21 pages, 14 figues, 8 tables. The data is available at this http URL . The software used for the cosmological analysis can be downloaded from this http URL
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Higher-order, non-Gaussian aspects of the large-scale structure carry valuable information on structure formation and cosmology, which is complementary to second-order statistics. In this work we measure second- and third-order weak-lensing aperture-mass moments from CFHTLenS and combine those with CMB anisotropy probes. The third moment is measured with a significance of $2\sigma$. The combined constraint on $\Sigma_8 = \sigma_8 (\Omega_{\rm m}/0.27)^\alpha$ is improved by 10%, in comparison to the second-order only, and the allowed ranges for $\Omega_{\rm m}$ and $\sigma_8$ are substantially reduced. Including general triangles of the lensing bispectrum yields tighter constraints compared to probing mainly equilateral triangles. Second- and third-order CFHTLenS lensing measurements improve Planck CMB constraints on $\Omega_{\rm m}$ and $\sigma_8$ by 26% for flat $\Lambda$CDM. For a model with free curvature, the joint CFHTLenS-Planck result is $\Omega_{\rm m} = 0.28 \pm 0.02$ (68% confidence), which is an improvement of 43% compared to Planck alone. We test how our results are potentially subject to three astrophysical sources of contamination: source-lens clustering, the intrinsic alignment of galaxy shapes, and baryonic effects. We explore future limitations of the cosmological use of third-order weak lensing, such as the nonlinear model and the Gaussianity of the likelihood function.

[33]  arXiv:1404.5487 [pdf, ps, other]
Title: Ion-molecule reactions involving HCO$^+$ and N$_2$H$^+$: Isotopologue equilibria from new theoretical calculations and consequences for interstellar isotope fractionation
Comments: to appear in A&A with 14 pages, 2 figures, and 10 tables
Subjects: Astrophysics of Galaxies (astro-ph.GA); Chemical Physics (physics.chem-ph)

$Aims$: We revisit with new augmented accuracy the theoretical dynamics of basic isotope exchange reactions involved in the $^{12}$C/$^{13}$C, $^{16}$O/$^{18}$O, and $^{14}$N/$^{15}$N balance because these reactions have already been studied experimentally in great detail. $Methods$: Electronic structure methods were employed to explore potential energy surfaces, full-dimensional rovibrational calculations to compute rovibrational energy levels that are numerically exact, and chemical network models to estimate the abundance ratios under interstellar conditions. $Results$: New exothermicities, derived for HCO$^+$ reacting with CO, provide rate coefficients markedly different from previous theoretical values in particular at low temperatures, resulting in new abundance ratios relevant for carbon chemistry networks. In concrete terms, we obtain a reduction in the abundance of H$^{12}$C$^{18}$O$^+$ and an increase in the abundance of H$^{13}$C$^{16}$O$^+$ and D$^{13}$C$^{16}$O$^+$. In all studied cases, the reaction of the ion with a neutral polarizable molecule proceeds through the intermediate proton-bound complex found to be very stable. For the complexes OCH$^+$...CO, OCH$^+$...OC, COHOC$^+$, N$_2$...HCO$^+$, N$_2$H$^+$...OC, and N$_2$HN$_2^+$, we also calculated vibrational frequencies and dissociation energies. $Conclusions$: The linear proton-bound complexes possess sizeable dipole moments, which may facilitate their detection.

[34]  arXiv:1404.5495 [pdf, ps, other]
Title: Inducing chaos by breaking axial symmetry in a black hole magnetosphere
Comments: 13 pages, 5 figures; accepted to ApJ
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

While the motion of particles near a rotating, electrically neutral (Kerr) and a charged (Kerr-Newman) black hole is always strictly regular, a perturbation to the gravitational or the electromagnetic field generally leads to chaos. Transition from regular to chaotic dynamics is relatively gradual if the system preserves axial symmetry, whereas non-axisymmetry induces chaos more efficiently. Here we study the development of chaos in an oblique (electro-vacuum) magnetosphere of a magnetized black hole. Besides the strong gravity of the massive source represented by the Kerr metric we consider the presence of a weak, ordered large-scale magnetic field. An axially symmetric model consisting of a rotating black hole embedded in an aligned magnetic field is generalized by allowing an oblique direction of the field having a general inclination with respect to the rotation axis of the system. Inclination of the field acts as an additional perturbation to the motion of charged particles as it breaks the axial symmetry of the system and cancels the related integral of motion. The axial component of angular momentum is no longer conserved and the resulting system thus has three degrees of freedom. Our primary concern within this contribution is to find out how sensitive the system of bound particles is to the inclination of the field. We employ the method of the maximal Lyapunov exponent to distinguish between regular and chaotic orbits and to quantify their chaoticity. We find that even a small misalignment induces chaotic motion.

[35]  arXiv:1404.5503 [pdf, ps, other]
Title: Cross-Correlation of Cosmic Shear and Extragalactic Gamma-ray Background: Constraints on the Dark Matter Annihilation Cross-Section
Comments: 32 pages, 8 figures, submitted to Phys. Rev. D
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We present the first measurement of the cross-correlation of weak gravitational lensing and the extragalactic gamma-ray background emission using data from the Canada-France-Hawaii Lensing Survey and the Fermi Large Area Telescope. The cross-correlation is a powerful probe of signatures of dark matter annihilation, because both cosmic shear and gamma-ray emission originate directly from the same DM distribution in the universe, and it can be used to derive constraints on dark matter annihilation cross-section. We show that the measured lensing-gamma correlation is consistent with a null signal. Comparing the result to theoretical predictions, we exclude dark matter annihilation cross sections of <sigma v> =10^{-24}-10^{-25} cm^3 s^-1 for a 100 GeV dark matter. If dark matter halos exist down to the mass scale of 10^-6 M_sun, we are able to place constraints on the thermal cross sections <sigma v> ~ 3 x 10^{-26} cm^3 s^-1 for a 10 GeV dark matter annihilation into tau^{+} tau^{-}. Future gravitational lensing surveys will increase sensitivity to probe annihilation cross sections of <sigma v> ~ 3 x 10^{-26} cm^3 s^-1 even for a 100 GeV dark matter. Detailed modeling of the contributions from astrophysical sources to the cross correlation signal could further improve the constraints by ~ 40-70 %.

[36]  arXiv:1404.5506 [pdf, ps, other]
Title: VLBI Observations of H2O Maser Annual Parallax and Proper Motion in IRAS 20143+3634: Reflection on the Galactic Constants
Comments: Intended for PASJ VERA special issue
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We report the results of VLBI observations of H$_{2}$O masers in the IRAS 20143+3634 star forming region using VERA (VLBI Exploration of Radio Astronomy). By tracking masers for a period of over two years we measured a trigonometric parallax of $\pi = 0.367 \pm 0.037$ mas, corresponding to a source distance of $D = 2.72 ^{+0.31}_{-0.25}$ kpc and placing it in the Local spiral arm. Our trigonometric distance is just 60% of the previous estimation based on radial velocity, significantly impacting the astrophysics of the source. We measured proper motions of $-2.99 \pm 0.16$ mas yr$^{-1}$ and $-4.37 \pm 0.43$ mas yr$^{-1}$ in R.A. and Decl. respectively, which were used to estimate the peculiar motion of the source as $(U_{s},V_{s},W_{s}) = (-0.9 \pm 2.9, -8.5 \pm 1.6, +8.0 \pm 4.3)$ km s$^{-1}$ for $R_0=8$ kpc and $\Theta_0=221$ km s$^{-1}$, and $(U_{s},V_{s},W_{s}) = (-1.0 \pm 2.9, -9.3 \pm 1.5, +8.0 \pm 4.3)$ km s$^{-1}$ for $R_0=8.5$ kpc and $\Theta_0=235$ km s$^{-1}$. IRAS 20143+3634 was found to be located near the tangent point in the Cygnus direction. Using our observations we derived the angular velocity of Galactic rotation of the local standard of rest (LSR), $\Omega_{0} = 27.3 \pm 1.6$ km s$^{-1}$ kpc$^{-1}$, which is consistent with previous values derived using VLBI astrometry of SFRs at the tangent points and Solar circle. It is higher than the value recommended by the IAU of $\Omega_{0} = 25.9$ km s$^{-1}$ kpc$^{-1}$ which was calculated using the Galactocentric distance of the Sun and circular velocity of the LSR.

[37]  arXiv:1404.5508 [pdf, ps, other]
Title: Discovery of new magnetic early-B stars within the MiMeS HARPSpol survey
Comments: 19 pages, 8 figures, accepted for publication in A&A
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

To understand the origin of the magnetic fields in massive stars as well as their impact on stellar internal structure, evolution, and circumstellar environment, within the MiMeS project, we searched for magnetic objects among a large sample of massive stars, and build a sub-sample for in-depth follow-up studies required to test the models and theories of fossil field origins, magnetic wind confinement and magnetospheric properties, and magnetic star evolution.
We obtained high-resolution spectropolarimetric observations of a large number of OB stars thanks to three large programs that have been allocated on the high-resolution spectropolarimeters ESPaDOnS, Narval, and the polarimetric module HARPSpol of the HARPS spectrograph. We report here on the methods and first analysis of the HARPSpol magnetic detections. We identified the magnetic stars using a multi-line analysis technique. Then, when possible, we monitored the new discoveries to derive their rotation periods, which are critical for follow-up and magnetic mapping studies. We also performed a first-look analysis of their spectra and identified obvious spectral anomalies (e.g., abundance peculiarities, Halpha emission), which are also of interest for future studies.
In this paper, we focus on eight of the 11 stars in which we discovered or confirmed a magnetic field from the HARPSpol LP sample (the remaining three were published in a previous paper). Seven of the stars were detected in early-type Bp stars, while the last star was detected in the Ap companion of a normal early B-type star. We report obvious spectral and multiplicity properties, as well as our measurements of their longitudinal field strengths, and their rotation periods when we are able to derive them. We also discuss the presence or absence of Halpha emission with respect to the theory of centrifugally-supported magnetospheres. (Abriged)

[38]  arXiv:1404.5514 [pdf, ps, other]
Title: The COS/UVES Absorption Survey of the Magellanic Stream. III: Ionization, Total Mass, and Inflow Rate onto the Milky Way
Comments: Accepted for publication in ApJ, 32 pages, 7 figures, 3 tables, Figure 1 shown at low resolution to reduce file size
Subjects: Astrophysics of Galaxies (astro-ph.GA)

Dynamic interactions between the two Magellanic Clouds have flung large quantities of gas into the halo of the Milky Way, creating the Magellanic Stream, the Magellanic Bridge, and the Leading Arm (collectively referred to as the Magellanic System). In this third paper of a series studying the Magellanic gas in absorption, we analyze the gas ionization level using a sample of 69 Hubble Space Telescope/Cosmic Origins Spectrograph sightlines that pass through or within 30 degrees of the 21 cm-emitting regions. We find that 81% (56/69) of the sightlines show UV absorption at Magellanic velocities, indicating that the total cross section of the Magellanic System is ~11 000 square degrees, or around a quarter of the entire sky. Using observations of the Si III/Si II ratio together with Cloudy photoionization modeling, we calculate that the total mass (atomic plus ionized) of the Magellanic System is ~2.0 billion solar masses, with the ionized gas contributing over twice as much mass as the atomic gas. This is larger than the current-day interstellar H I mass of both Magellanic Clouds combined, indicating that they have lost most of their initial gas mass. If the gas in the Magellanic System survives to reach the Galactic disk over its inflow time of ~0.5-1.5 Gyr, it will represent an average inflow rate of ~3.7-6.7 solar masses per year, potentially raising the Galactic star formation rate. However, multiple signs of an evaporative interaction with the hot Galactic corona indicate that the Stream may not survive its journey to the disk fully intact, and will instead add material to (and cool) the corona.

[39]  arXiv:1404.5526 [pdf, other]
Title: Cloud angular momentum and effective viscosity in global SPH simulations with feedback
Comments: Submitted to MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We examine simulations of isolated galaxies to analyse the effects of localised feedback on the formation and evolution of molecular clouds. Feedback contributes to turbulence and the destruction of clouds, leading to a population of clouds that is younger, less massive, and with more retrograde rotation. We investigate the evolution of clouds as they interact with each other and the diffuse ISM, and determine that the role of cloud interactions differs strongly with the presence of feedback: in models with feedback, mergers between clouds decrease the number-fraction of prograde clouds, while in models without feedback, scattering events increase the prograde fraction. We also produce an estimate of the viscous time-scale due to cloud-cloud collisions, which increases with the inclusion of feedback (~20 Gyr vs ~10 Gyr), but is still much smaller than previous estimates (~1000 Gyr); although collisions become more frequent with feedback, less energy is lost in each collision.

[40]  arXiv:1404.5567 [pdf, ps, other]
Title: Variable Speed of Light Cosmology, Primordial Fluctuations and BICEP2
Authors: J. W. Moffat
Comments: 10 pages, no figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

A variable speed of light cosmology is formulated in which the speed of light is described in the action by a dynamical field $\phi$. The initial value problems of cosmology: the horizon and flatness problems are solved. The model predicts primordial scalar and tensor fluctuation spectral indices $n_s=0.96$ and $n_t=- 0.04$, respectively. The BICEP2 observation of $r=0.2$ yields $r/n_t=-5$ which is close to the single field inflationary consistency condition $r/n_t=-8$.

[41]  arXiv:1404.5578 [pdf, ps, other]
Title: Fe I Oscillator Strengths for the Gaia-ESO Survey
Comments: Accepted for publication in Mon. Not. R. Astron. Soc
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Instrumentation and Methods for Astrophysics (astro-ph.IM)

The Gaia-ESO Public Spectroscopic Survey (GES) is conducting a large-scale study of multi-element chemical abundances of some 100 000 stars in the Milky Way with the ultimate aim of quantifying the formation history and evolution of young, mature and ancient Galactic populations. However, in preparing for the analysis of GES spectra, it has been noted that atomic oscillator strengths of important Fe I lines required to correctly model stellar line intensities are missing from the atomic database. Here, we present new experimental oscillator strengths derived from branching fractions and level lifetimes, for 142 transitions of Fe I between 3526 {\AA} and 10864 {\AA}, of which at least 38 are urgently needed by GES. We also assess the impact of these new data on solar spectral synthesis and demonstrate that for 36 lines that appear unblended in the Sun, Fe abundance measurements yield a small line-by-line scatter (0.08 dex) with a mean abundance of 7.44 dex in good agreement with recent publications.

[42]  arXiv:1404.5589 [pdf, other]
Title: Model-Independent Measurements of Cosmic Expansion and Growth at z=0.57 Using the Anisotropic Clustering of CMASS Galaxies From the Sloan Digital Sky Survey Data Release 9
Authors: Yun Wang
Comments: 7 pages, 4 figures. Submitted
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We analyze the anisotropic two dimensional galaxy correlation function (2DCF) of the CMASS galaxy sample from the Sloan Digital Sky Survey Data Release 9 (DR9) of the Baryon Oscillation Spectroscopic Survey (BOSS) data. Modeling the 2DCF fully including nonlinear effects and redshift space distortions (RSD) in the scale range of 30 to 120 h^{-1}Mpc, we find H(0.57)r_s(z_d)/c=0.0444 +/- 0.0019, D_A(0.57)/r_s(z_d)=9.01 +/- 0.23, and f_g(0.57)\sigma_8(0.57)=0.474 +/- 0.075, where r_s(z_d) is the sound horizon at the drag epoch computed using a simple integral, and f_g(z) is the growth rate at redshift z, and \sigma_8(z) represents the matter power spectrum normalization on 8h^{-1}Mpc scale at z. We find that the scales larger than 120 h^{-1}Mpc are dominated by noise in the 2DCF analysis, and that the inclusion of scales 30-40 h^{-1}Mpc significantly tightens the RSD measurement. Our measurements are consistent with previous results using the same data, but have significantly better precision since we are using all the information from the 2DCF in the scale range of 30 to 120 h^{-1}Mpc. Our measurements have been marginalized over sufficiently wide priors for the relevant parameters; they can be combined with other data to probe dark energy and gravity.

[43]  arXiv:1404.5597 [pdf, other]
Title: Large-scale magnetic fields in Bok globules
Comments: 9 pages, 7 figures, accepted by A&A
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Instrumentation and Methods for Astrophysics (astro-ph.IM)

Context: The role of magnetic fields in the star formation process is a contentious matter of debate. In particular, no clear observational proof exists of a general influence by magnetic fields during the initial collapse of molecular clouds. Aims: Our aim is to examine magnetic fields and their influence on a wide range of spatial scales in low-mass star-forming regions. Method: We trace the large-scale magnetic field structure on scales of 10^3-10^5 AU in the local environment of Bok globules through optical and near-infrared polarimetry and combine these measurements with existing submillimeter measurements, thereby characterizing the small-scale magnetic field structure on scales of 10^2-10^3 AU. Results: For the first time, we present polarimetric observations in the optical and near-infrared of the three Bok globules B335, CB68, and CB54, combined with archival observations in the submillimeter and the optical. We find a significant polarization signal (P>=2%, P/sigma(P)>3) in the optical and near-infrared for all three globules. Additionally, we detect a connection between the structure on scales of 10^2-10^3 AU to 10^3-10^4 AU for both B335 and CB68. Furthermore, for CB54, we trace ordered polarization vectors on scales of ~10^5 AU. We determine a magnetic field orientation that is aligned with the CO outflow in the case of CB54, but nearly perpendicular to the CO outflow for CB68. For B335 we find a change in the magnetic field oriented toward the outflow direction, from the inner core to the outer regions. Conclusion: We find strongly aligned polarization vectors that indicate dominant magnetic fields on a wide range of spatial scales.

Cross-lists for Wed, 23 Apr 14

[44]  arXiv:1404.4883 (cross-list from hep-th) [pdf, ps, other]
Title: A small cosmological constant from Abelian symmetry breaking
Authors: Gianmassimo Tasinato (ICG, Portsmouth)
Comments: 14 pages, no figures
Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)

We investigate some cosmological consequences of a vector-tensor theory where an Abelian symmetry in the vector sector is slightly broken by a mass term and by ghost-free derivative self-interactions. When studying cosmological expansion in the presence of large bare cosmological constant $\Lambda_{cc}$, we find that the theory admits branches of de Sitter solutions in which the scale of the Hubble parameter is inversely proportional to a power of $\Lambda_{cc}$. Hence, a large value of $\Lambda_{cc}$ leads to a small size for the Hubble scale. In an appropriate limit, in which the symmetry breaking parameters are small, the theory recovers the Abelian symmetry plus an additional Galileon symmetry acting on the longitudinal vector polarization. The approximate Galileon symmetry can make the structure of this theory stable at the energy scales we are interested in. We also analyze the dynamics of linearized cosmological fluctuations around the de Sitter solutions, showing that no manifest instabilities arise, and that the transverse vector polarizations become massless around these configurations.

[45]  arXiv:1404.5446 (cross-list from hep-ph) [pdf, other]
Title: Magnetic dark matter for the X-ray line at 3.55 keV
Authors: Hyun Min Lee
Comments: 12 pages, 5 figures
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We consider a decaying magnetic dark matter explaining the X-ray line at 3.55 keV identified recently from XMM-Newton observations. We introduce two singlet Majorana fermions that have almost degenerate masses and fermion-portal couplings with a charged scalar of weak scale mass. In our model, an approximate $Z_2$ symmetry gives rise to a tiny transition magnetic moment between the Majorana fermions at one loop. The heavier Majorana fermion becomes a thermal dark matter due to the sizable fermion-portal coupling to the SM charged fermions. We find the parameter space for the masses of dark matter and charged scalar and their couplings, being consistent with both the relic density and the X-ray line. Various phenomenological constraints on the model are also discussed.

[46]  arXiv:1404.5518 (cross-list from hep-ph) [pdf, ps, other]
Title: Axion monodromy inflation with sinusoidal corrections
Comments: 11 pages, 3 figures
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)

We study the axion monodromy inflation with a non-perturbatively generated sinusoidal term. The potential form is a mixture between the natural inflation and the axion monodromy inflation potentials. The sinusoidal term is subdominant in the potential, but leaves significant effects on the resultant fluctuation generated during inflation. A larger tensor-to-scalar ratio can be obtained in our model. We study two scenarios, single inflation scenario and the double inflation scenario. In the first scenario, the axion monodromy inflation with a sufficient number of e-fold generates a larger tensor-to-scalar ratio about $0.1 - 0.15$ but also a tiny running of spectral index. In the second scenario of double inflation, axion monodromy inflation is its first stage and, we assume another inflation follows. In this case, our model can realize a larger tensor-to-scalar ratio and a large negative running of spectral index simultaneously.

Replacements for Wed, 23 Apr 14

[47]  arXiv:1305.7264 (replaced) [pdf, other]
Title: The Moving Group Targets of the SEEDS High-Contrast Imaging Survey of Exoplanets and Disks: Results and Observations from the First Three Years
Comments: 26 pages, 4 figures, 6 tables. Replaced with published ApJ version
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
[48]  arXiv:1308.3197 (replaced) [pdf, ps, other]
Title: "Self-absorbed" GeV light-curves of Gamma-Ray Burst afterglows
Comments: 8 pages, to appear in the ApJ
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[49]  arXiv:1308.5705 (replaced) [pdf, other]
Title: Light NMSSM Neutralino Dark Matter in the Wake of CDMS II and a 126 GeV Higgs
Comments: v2: Several significant revisions, but overall conclusions unchanged. Matches version published in PRD
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[50]  arXiv:1310.4177 (replaced) [pdf, ps, other]
Title: Direct measurements of dust attenuation in z~1.5 star-forming galaxies from 3D-HST: Implications for dust geometry and star formation rates
Comments: Accepted for publication in the Astrophysical Journal (13 pages, 9 figures)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[51]  arXiv:1310.6362 (replaced) [pdf, ps, other]
Title: An ALMA Survey of Submillimetre Galaxies in the Extended Chandra Deep Field South: The Far-Infrared Properties of SMGs
Authors: Mark Swinbank (1), James Simpson (1), Ian Smail (1), Chris Harrison (1), Jacqueline Hodge (2), Alex Karim (3), Fabian Walter (2), Dave Alexander (1), Niel Brandt (4), Carlos de Breuck (5), Elizabete da Cunha (2), Scott Chapman (6), Kristen Coppin (7), Alice Danielson (1), Helmut Dannerbauer (8), Roberto Decarli (2) Thomas Greve (9), Rob Ivison (10), Kirsten Knudsen (11), Claudia Lagos (5), Eva Schinnerer (2), Alasdair Thomson (1), Julie Wardlow (12), Axel Weiss (3), Paul van der Werf (13) ((1) ICC, Durham, (2) Heidelberg, (3) Bonn, (4) Penn State, (5) ESO, (6) Dalhousie, (7) Hertfordshire, (8) Vienna, (9) UCL, (10) IfA, Edinburgh, (11) Chalmers, (12) UC Irvine, (13) Leiden)
Comments: Accepted for publication in MNRAS. 24 pages, 12 figures
Journal-ref: Swinbank et al. 2014, MNRAS, 423, 1267
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[52]  arXiv:1310.7328 (replaced) [pdf, ps, other]
Title: HD 285507b: An Eccentric Hot Jupiter in the Hyades Open Cluster
Authors: S. N. Quinn (1 and 4), R. J. White (1), D. W. Latham (2), L. A. Buchhave (2 and 3), G. Torres (2), R. P. Stefanik (2), P. Berlind (2), A. Bieryla (2), M. C. Calkins (2), G. A. Esquerdo (2), G. Fürész (2), J. C. Geary (2), A. H. Szentgyorgyi (2) ((1) Georgia State University, (2) Harvard-Smithsonian Center for Astrophysics, (3) Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, (4) NSF Graduate Research Fellow)
Comments: 11 pages, 6 figures, 3 tables. Accepted for publication in ApJ. Minor changes from v1: updated to match published version
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
[53]  arXiv:1311.1600 (replaced) [pdf, other]
Title: Distinguishing between inhomogeneous model and $Λ\textrm{CDM}$ model with the cosmic age method
Comments: 10 pages, 2 figures, accepted by Physics Letters B. arXiv admin note: text overlap with arXiv:0911.3852 by other authors
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[54]  arXiv:1311.5761 (replaced) [pdf, ps, other]
Title: Rest-frame ultra-violet spectra of massive galaxies at z=3: evidence of high-velocity outflows
Comments: 17 pages, 14 figures, Accepted for publication in A&A
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[55]  arXiv:1312.0273 (replaced) [pdf, ps, other]
Title: Impact of Dark Matter Velocity Distributions on Capture Rates in the Sun
Comments: 20 pages, 8 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[56]  arXiv:1312.0566 (replaced) [pdf, other]
Title: Late evolution of relic gravitational waves in coupled dark energy models
Comments: 22 pages, 8 figures, article
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[57]  arXiv:1312.3967 (replaced) [pdf, ps, other]
Title: Identifying high-redshift GRBs with RATIR
Comments: Accepted by AJ. 15 pages, 8 figures, 4 tables
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[58]  arXiv:1401.1082 (replaced) [pdf, ps, other]
Title: PolarBase: a data base of high resolution spectropolarimetric stellar observations
Comments: Accepted for publication in PASP
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Instrumentation and Methods for Astrophysics (astro-ph.IM)
[59]  arXiv:1401.3965 (replaced) [pdf, ps, other]
Title: Mirror dark matter: Cosmology, galaxy structure and direct detection
Authors: R. Foot
Comments: 130 pages
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
[60]  arXiv:1401.7031 (replaced) [pdf, ps, other]
Title: Probing Quintessence Potential with Future Cosmological Surveys
Comments: 36 pages, 10 figures, 6 tables, minor changes to the footnote and figures; published in JCAP
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
[61]  arXiv:1403.5560 (replaced) [pdf, ps, other]
Title: Prospecting in Ultracool Dwarfs: Measuring the Metallicities of Mid- and Late-M Dwarfs
Comments: Accepted to AJ. 13 pages, 6 figures, 5 tables. NIR spectra of companions included. IDL program to apply calibration is available at this http URL
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
[62]  arXiv:1403.7534 (replaced) [pdf, ps, other]
Title: Multifrequency Studies of the Peculiar Quasar 4C +21.35 During the 2010 Flaring Activity
Authors: M. Ackermann (1), M. Ajello (29), A. Allafort (39), E. Antolini (4,5), G. Barbiellini (6,7), D. Bastieri (8,9), R. Bellazzini (10), E. Bissaldi (11), E. Bonamente (5,4), J. Bregeon (10), M. Brigida (12,13), P. Bruel (14), R. Buehler (1), S. Buson (8,9), G. A. Caliandro (3), R. A. Cameron (3), P. A. Caraveo (15), E. Cavazzuti (16), C. Cecchi (5,4), R. C. G. Chaves (17), A. Chekhtman (18), J. Chiang (3), G. Chiaro (9), S. Ciprini (16,19), R. Claus (3), J. Cohen-Tanugi (20), J. Conrad (21,22,23,24), S. Cutini (16,19), F. D'Ammando (25), F. de Palma (12,13), C. D. Dermer (26), E. do Couto e Silva (3), D. Donato (27,28), P. S. Drell (3), C. Favuzzi (12,13), J. Finke (26), W. B. Focke (3), A. Franckowiak (3), Y. Fukazawa (29), P. Fusco (12,13), F. Gargano (13), D. Gasparrini (16,19), N. Gehrels (30), et al. (247 additional authors not shown)
Comments: 46 pages, 10 figures, 4 tables. Astrophysical Journal, in press. Contact Authors: Filippo D'Ammando, Justin Finke, Davide Donato, Josefa Becerra Gonzalez, Tomislav Terzic
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
[63]  arXiv:1404.2996 (replaced) [pdf, ps, other]
Title: Inert Dark Matter in Type-II Seesaw
Comments: 31 pages, 24 figures, 6 tables; References added
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex)
[64]  arXiv:1404.3556 (replaced) [pdf, ps, other]
Title: Intrinsic $γ$-ray luminosity, black hole mass, jet and accretion in Fermi blazars
Comments: 24 pages, 1 table, 18 figures, Accepted for publication in MNRAS. arXiv admin note: text overlap with arXiv:1209.4702, arXiv:1012.0308 by other authors. text overlap with arXiv:1209.4702 by other authors
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[65]  arXiv:1404.3690 (replaced) [pdf, ps, other]
Title: Reconstruction of the primordial power spectra with Planck and BICEP2
Comments: complementary results without BICEP2 added, references add, typos corrected, 10 figures, 5 tables, 11 pages
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
[66]  arXiv:1404.4709 (replaced) [pdf, ps, other]
Title: The Higgs vacuum is unstable
Comments: 8 pages - v2: references added
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
[67]  arXiv:1404.4817 (replaced) [pdf, ps, other]
Title: Faint Population III supernovae as the origin of the most iron-poor stars
Comments: Submitted to the Astrophysical Journal Letters, The list of references is corrected
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
[68]  arXiv:1404.4870 (replaced) [pdf, other]
Title: Towards precision distances and 3D dust maps using broadband Period--Magnitude relations of RR Lyrae stars
Comments: 21 pages, 29 figures, 2 tables, abstract abridged for arXiv
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Instrumentation and Methods for Astrophysics (astro-ph.IM)
[69]  arXiv:1404.5276 (replaced) [pdf, other]
Title: RF heating efficiency of the terahertz superconducting hot-electron bolometer
Subjects: Instrumentation and Detectors (physics.ins-det); Instrumentation and Methods for Astrophysics (astro-ph.IM); Superconductivity (cond-mat.supr-con); Computational Physics (physics.comp-ph)
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