Day 770

Thursday.  Friday.

1410.5812
Gas around galaxy haloes: methodology comparisons using hydrodynamical simulations of the intergalactic medium
Meiskin, Bolton, Tittley

IGM cosmo hydro sim at z~3 (GADGET-3 and Enzo) to model the gaseous environments of galaxies.  Identify haloes in the simulations using 3 different algorithms.  Different rank orderings of the haloes by mass result, introducing a limiting factor in identifying haloes with observed galaxies.   Also compare the physical properties of the gas between the two codes, focussing primarily on the gas outside the viral radius, motivated by recent HI absorption measurements of the gas around z~ 2-3 galaxies.  The internal dispersion velocities of the gas in the haloes have converged for a box size of 30 comoving Mpc, but the CoM peculiar velocities of the haloes have not up to a box size of 60 comoving Mpc.  The density and temperature of the gas within the instantaneous turn-around radii of the haloes are adequately captured for box sizes 30 Mpc on a side, but the results are highly sensitive to the treatment of unresolved, rapidly cooling gas, with the gas mass fraction within the viral radius severely depleted by SF in the GADGET-3 simulations  Convergence of the gas peculiar velocity field on large scales requires a box size of a least 60 Mpc.  Outside the turn-around radius, the physical state of the gas agrees to 30% or better both with box size and between simulation methods.  Conclude that generic IGM simulations make accurate predictions for the intergalactic gas properties beyond the halo turn-around radii, but the gas properties on smaller scales are highly dependent on SF and feedback implementations.

1410.5814
Possible signature of distant foreground in the Planck data
Yershov, Orlov, Raikov

Checked and confirmed the existence of a correlation between SN redshifts, z_SN, and CMB temperature fluctuations at the SNe locations, T_SN, which was reported for WMAP, and now seen in Planck map.  5sigma significance.  Correlation becomes even stronger for SNe Ia, but vanishes for other types.  Excluded the possibility of this anomaly being caused by SZ effect.  Remaining possibility is some, unaccounted for, contribution to the CMB from z>0.3 FG though either ISW or thermal emission from IGM.

1410.5817
The dark matter haloes of moderate luminosity X-ray AGN as determined from weak gravitational lensing and host stellar masses
Leauthaud, et al

Show that better constraints of AGN and DM halo relation can be achieved through a rigorous comparison of the clustering, lensing, and cross-correlation signals of AGN hosts to a fiducial stellar-to-halo mass relation (SMHR) derived for all galaxies.  The technique exploits the fact that the global SHMR can be measured with much higher accuracy than any statistic derived from AGN samples alone.  Using 382 moderate luminosity X-ray AGN at z<1 from the COSMOS field, report the first measurements of weak gravitational lensing from an X-ray selected sample.  Comparing this signal to predictions from the global SHMR, find that contrary to previous results, most X-ray AGN do not live in medium size groups - nearly half reside in relatively low mass haloes with Mh~1e12.5 Msun.  The AGN occupation function is well described by the same form derived for all galaxies but with a lower normalization - the fraction of haloes with AGN in the sample is a few percent.  By highlighting the relatively "normal" way in which moderate luminosity X-ray AGN hosts occupy haloes, the results suggest that the environmental signature of distinct fueling modes for luminous QSOs compared to moderate luminosity X-ray AGN is less obvious than previously claimed.

1410.6050
Comparing gravitational redshifts of SDSS galaxy clusters with the magnification redshift enhancement of background BOSS galaxies
Jimeno, Broadhurst, Coupon, Umetsu, Lazkoz

A clean measurement of the evolution of the galaxy cluster MF can significantly improve the understanding of cosmology from the rapid growth of cluster masses below z<0.5.  Examine the consistency of cluster catalogs selected from the SDSS by applying two independent gravity-based methods using all available spectroscopic z from the DR10 release.  First, detect a gravitational z related signal for 20k and 13k clusters with spec z contained in the GMBCG and redMaPPer catalogues, at a level of ~-10 km/s.  This is consistent with the magnitude expected using richness-mass relations provided by the literature and after applying recently clarified relativistic and flux bias corrections.  This signal is also consistent with the richest clusters in the larger catalogue of Wen+2012, corresponding to M_200m>2e14 Msun/h, however find no significant detection of gravitational redshift signal for less rich clusters, which may be related to bulk motions from substructure and serious cluster detections.  Second, find all three catalogues generate mass-dependent levels of lensing magnification bias, which enhances the mean redshift of flux-selected BG galaxies from the BOSS survey.  The magnitude of this lensing effect is generally consistent with the corresponding richness-mass relations advocated for the surveys.  Conclude that all catalogues comprise a high proportion of reliable clusters, and that the CMBCG and redMaPPer cluster finder algorithms favor more relaxed clusters with a meaningful gravitational redshift signal, as anticipated by the red-sequence color selection of the GMBCG and redMaPPer samples.