Day 413

Tuesday.

1304.3465
Turbulence driven by structure formation in the circum-galactic medium
Iapichino, Viel, Borgani

Use mesh-based hydro code Enzo with sub-grid-scale (SGS) model for unresolved turbulence, to investigate injection of turbulence in circum-galactic medium at z=2.  Include radiative cooling and heating by uniform UV BG; compared with the effect of turbulence modeling.  Mechanisms of gas exchange between galaxies and the surrounding medium, as well as metal enrichment, are not taken into account, and turbulence is here driven solely by structure formation (mergers and shocks).  Find that turbulence, both at resolved and SGS scales, impacts mostly the WHIM, with 1e5<T<1e7 K, mainly located around collapsed and shock heated structures, and in filaments.  Typical values of the ratio of turbulent to thermal pressure is 0.1 in the WHIM, corresponding to a volume-weighted average of the SGS turbulent to thermal Doppler broadening b_t/b_therm = 0.26, on length scales below the grid resolution of 25 kpc/h.  In the diffuse IGM, defined in a range of baryon over density /delta/ between 1 and 50, the importance of turbulence is smaller, but grows as a function of gas density, and the Doppler broadening ratio is fitted by the function b_t/ b_therm = 0.023 /delta^0.58.

1304.3466
Composition of low redshift halo gas
Cen

Halo gas in z<0.5, >0.1L* galaxies in high-res, large-scale cosmo hydro sims is examined with respect to 3 components: (cold, warm, hot) with temperatures equal to <1e5, 1e5-6, >1e6K, respectively.  Warm component agree to observations wrt galaxy-O VI line correlation, etc.  Detailed account of sources of warm halo gas (stellar feedback heating, gravitational shock heating and accretion from IGM), inflowing and outflowing warm halo gas metallicity disparities and their dependencies on galaxy types and environment is also presented.  Predict: (1) cold gas is the primary component in inner regions, with its mass comprising 50% of all gas within galacto-centric radius r=(30,150) kpc in (red, blue) galaxies.  (2) at r>(30,200)kpc in (red, blue) galaxies, the hot component becomes the majority.  (3) the warm component is a perpetual minority, with its contribution peaking at ~30% at r=100-300kpc in blue galaxies, and never exceeding 5% in red galaxies.  The significant amount of cold gas in low-z early-type galaxies found in simulations, in agreement with recent observations (Thom et al.), is intriguing, so is the dominance of hot gas at large radii in blue galaxies.

1304.3474
The synergy between the Dark Energy Survey and the South Pole Telescope
Vallinotto

DES has 150 sq. deg in Science Verification phase.  Forecast for DES-SV and full survey of 5000 sq. deg.  DES-SV and SPT-SZ allow a ~8% measurement of the linear galaxy bias in 4 redshift bins.  Further show that a joint analysis of cosmic shear, galaxy density and CMB lensing data allows to self calibrate the shear multiplicative bias and the linear galaxy bias to the percent or sub-percent level, depending on the quality of available data, fraction of overlap of the footprints and priors included in the analysis.

1304.3492
Estimating gas masses and dust-to-gas ratios from optical spectroscopy
Brinchmann, Charlot, Kauffmann, Heckman, White, Tremonti

Exploit the sensitivity of certain optical lines to changes in depletion of metals onto dust grains and uses photo-ionization models to constrain these physical ratios along with Z and dust column density.  Technique independent of conversion factor of CO to H2; show Z-dependent XCO is required to achieve good agreement between measurements and those provided by CO and HI.  This method cannot be reliably aperture corrected to total gas mass. Compare results to SDSS DR7 galaxies, Z dependence agrees well with FIR data [FIR presumably from heated dust].  ...

1304.3665
The cosmic X-ray background: abundance and evolution of hidden black holes
Gilli

Review paper of XRB.  XRB spectral shape suggests a large population of distant, hidden nuclei must exist, now being revealed at higher and higher z by Chandra and XMM.  

1304.3715
A resolution of the cosmic Lithium problem
Ouyed

A quark-novae (QNe) occurring in the wake of Pop III stars.

1304.3717
Linking X-ray AGN with DM haloes: a model compatible with AGN luminosity function and large-scale clustering properties
Hütsi, Gilfanov, Sunyaev

Assume a simple population-averaged scaling relation between AGN X-ray Luminosity L_X and the host dark matter halo mass M_h exists: then L_X LF can be computed from halo mass function.  Find M_h-L_X relation required to match the z-dependent AGN X-ray luminosity function known from X-ray observations.  Find that with the simple power law scaling M_h propto L_X^Gamma(z), model can successfully reproduce the observed X-ray luminosity function.   ....  Suggest that the typical X-ray AGN are dominantly fueled via relatively inefficient 'hot-halo' accretion mode.

1304.3724
New constraints on the early expansion history
Hojjati, Linder, Samsing

Test early universe's expansion rate and constituents such as effective number of relativistic degrees of freedom and DE with the most recent data from Planck and WMAP9.  Constraint expansion history in a model independent manner from z=0 to 1e5.  Hubble parameter mapped to a few precent precision, limiting early DE and extra relativistic degrees of freedom within a model independent approach to 2-16% and 0.71 equivalent neutrino species respectively (95% CL).  Within dark radiation, barotropic aether, and Doran-Robbers models, the early DE constraints are 3.3%, 1.9%, and 1.2% respectively.

1304.4124
Gravitational redshifts from large-scale structure
Croft

Use halo model of clustering to predict the distortion due to gravitational redshifts of the cross-correlation function on scales from 1-100 Mpc/h.  Compare predictions to simulations and use the simulations to make mock catalogues relevant to current and future galaxy redshift surveys.  Without formulating an optimal estimator, find that the full BOSS survey would be able to detect gravitational redshifts from large-scale structure at the 4 sigma level.  Upcoming z surveys will greatly increase the number of galaxies; BigBOSS and Euclid should be capable of measurements with precision at the few percent level.  Other interesting effects including relativistic beaming and transverse Doppler shift can add additional asymmetric distortions to the correlation function.  While these contributions are subdominant to the gravitational redshift on large scales, they represent additional opportunities to probe gravitational physics and indicate that many qualitatively new measurements should be possible using large z surveys.

1304.4172
Quasar lensing
Jackson

REview observations of gravitationally lensed quasars.  Systems important because they allow us to probe the properties of lensing galaxies at various scales, and also allow insights into the structures of the quasars themselves.  Samples of quasar lenses also have the potential to act as cosmographic probes.  These areas are described, together with observational and scientific prospects for the future.