Day 634

Easter Monday.

1404.4630
Formation of an embryonic supermassive star in the first galaxy
Inayoshi, Omukai, Tasker

Study gravitational collapse of ~8000K primordial gas cloud as a candidate progenitor for a supermassive star (SMS, >1e5 Msun) using a 3d hydrosim, including all the relevant cooling processes of both H2 and H, which can potentially induce cloud fragmentation.  This is the first simulation of this kind to resolve protostar formation.  Find that the cloud undergoes runaway collapse without a major episode of fragmentation.  Although the H2 fraction jumps by a large factor via the 3 body reaction at 1e-13 g/cm3, its cooling remains inefficient due to the optical thickness, and the temperature remains >3000 K.  When the central core of the cloud becomes opaque to continuum radiation at 1e-8 g/cm3, a hydrostatic protostar with ~0.2 Msun is formed.  The protostar grows to mass ~1 Msun and radius ~2 AU within ~1 yr via rapid accretion of dense filamentary flows.  WIth a high accretion rate ~ 2 Msun/yr, the protostar is expected to turn into a SMS within its lifetime, eventually collapsing to a seed for the SMBH observed in the early universe at z~7.

1404.4632
Line emitting galaxies beyond a redshift of 7: an improved method for estimating the evolving neutrality of the intergalactic medium
Schenker, Ellis, Konidaris, Stark

The z-dependent fraction of color-selected galaxies revealing Ly-a emission has become the most valuable constraint on the evolving neutrality of the early IGM.  However, in addition to resonant scattering by neutral gas, the visibility of Ly-a is also dependent on the intrinsic properties of the host galaxy, including its stellar population, dust content and the nature of outflowing gas.  Taking advantage of significant progress made in determining the line emitting properties of z~4-6 galaxies, propose an improved method, based on using the measured slopes of the rest-frame UV continua of galaxies, to interpret the growing body of NIR spectra of z>7 galaxies in order to take into account these host galaxy dependencies.  In a first application of the new method, demonstrate its potential via a new spectroscopic survey of 7<z<8 galaxies undertaken with the Keck MOSFIRE spectrograph.  Together with earlier published data, the data provides improved estimates of the evolving visibility of Lya, particularly at z~8.  As a byproduct, also present a new line emitting galaxy at z~7.62 which supersedes an earlier z record.  Discuss the improving constraints on the evolving neutral fraction over 6<z<8 and the implications for cosmic reionization.

1404.4808
Probing the diffuse braying distribution with the lensing-tSZ cross-correlation
Ma, Waerbeke, Hinshaw, Hojjati, Scott

Approximately half of the Universe's baryons are in a form that has been hard to detect directly.  However, the missing component can be traced through the cross-correlation of the tSZ effect with WL.  Build a model for this correlation and use it to constrain the extended baryon component, employing data from the CFHTLenS and Planck satellite.  The measured correlation function is consistent with an isothermal beta-model for the halo gas pressure profile, and the 1- and 2-halo terms are both detected at the 4 sigma level.  The effective virial temperature of the gas is found to be in the range 7e5-3e8K, with approximately 50 [%?] of the baryons appearing to lie beyond the virial radius of the halos, consistent with current expectations for the warm-hot IGM.