1205.2368
High-velocity outflows without AGN feedback Eddington-limited star formation in compact massive galaxies
Diamond-Stanic, Moustakas, Tremonti, Coil, Hickox, Robaina, Rudnick, Sell
Present the discovery of compact, obscured star formation in galaxies at z~0.6 that exhibit >1000 km/s outflows. With HST/WISE, estimate SFR surface densities of 3000 Msun/yr/kpc^2, comparable to the Eddington limit from radiation pressure on dust grains. Argue that feedback associated with a compact starburst in the form of radiation pressure from massive stars and ram pressure from supernovae and stellar winds is sufficient to produce the high-velocity outflows observed, without the need to invoke feedback from an AGN.
1205.2369
The Atacama cosmology telescope: relation between galaxy cluster optical richness and Sunyaev-Zel'dovich effect
Sehgal,.. Das, Devlin, Dunkley, ... Halpern, ... Hughes, .. Lin, et al
Measured SZ flux from 474 optically-selected MaxBCG clusters that fall within the ACN equatorial survey region; covers 510 sq deg and overlaps stripe 82 of SDSS. Stacked SZ flux on 52 X-ray-selected MCXC clusters in equatorial and southern ACT sure region, covering 455 sqdeg. Find: measured SZ flux from the x-ray selected clusters is consistent with expectations; but from optically selected clusters, it is both significantly lower than expectations and lower than the recovered SZ flux measured by Planck. Suspect: significant offset between optically-selected brightest cluster galaxies (BCGs) and the SZ centers (ACT has finer resolution so is more sensitive to this); such offsets can arise due to either an intrinsic physical separation between the BCG and the center of the gas concentration or from misidentification of the cluster BCG. Find: entire discrepancy for both ACT and Planck can be explained by assuming that the BCGs are offset from the SZ maxima with a uniform random distribution between 0 and 1.5 Mpc. In contrast, the physical separation between BCGs and X-ray peaks for an X-ray selected subsample of MaxBCG clusters shows a much narrower distribution that peaks within 0.2 Mpc. Conclude that while offsets between BCGs and SZ peaks may be an important component in explaining the discrepancy, it is likely that a combination of factors is responsible for the ACT and Planck measurements.
1205.2370
AzTEC half square degree survey of the SHADES fields -- II. Identifications, redshifts, and evidence for large-scale structure
Michalowski, et al
Blind sub-mm survey, redshift distribution (median z~2.2) of galaxies (down to 1mJy) similar to SCUBA.
1205.2373
Residual Cooling and persistent star formation amid AGN feedback in Abell 2597
Tremblay et al
* Abell2597: shows x-ray and radio "cavities" that seem to be evidence of energetic outflow from the central region.
AGN heating and ICM cooling in the BCG of Abell2597 studied. ... Conclude cooling ICM is the dominant contributor of the cold gas reservoir fueling SF and AGN activity in this BCG.
1205.2374
Multiphase signatures of AGN feedback in Abell 2597
Tremblay, et al
Extensive kpc-scale X-ray cavity network, as well as 15 kpc filament of slft-excess gas exhibiting strong spatial correlation with archival VLA radio data. Filament may be associated with multiphase (1e3-1e7 K) gas that has been entrained and dredged up by the propagating radio source. ...
1205.2375
Cosmology in 2D: the concentration-mass relation for galaxy clusters
Giocoli, Meneghetti, Ettori, Moscardini
Systematic study of the measures of the mass and concentration estimated by fitting the convergence profile of a large sample of mock galaxy cluster size lenses. Main contribution to the bias in mass and in concentration is due to the halo triviality and second to the presence of substructures within the host halo virial radius. Knowing the cluster elongation along the line of sight helps in correcting the mass bias, but still keeps a small negative bias for the concentration. If these mass and concentration biases characterize the galaxy cluster sample of a wide field survey, it will be difficult to well recover within one sigma the cosmological parameters that mainly influence the c-M relation, using as reference a 3d c-M relation measured in cosmological N-body simulation. In this work, propose how to correct the c-M relation for projection effects and for adiabatic contraction and suggest to use these as reference for real observed data. Correcting mass and concentration estimates gives a measurement of the cosmological parameter within 1-sigma confidence contours.
* I need to read this for the SM cluster project.
1205.2384
Hubble flows and gravitational potentials in observable universe
Eingorn, Zhuk
Consider the Universe deep inside of the cell of uniformity. Inhomogeneously distributed discrete structures disturb the BG Friedmann model. Propose mathematical models with conformally flat, hyperbolic and spherical spaces; obtain the gravitational potential for an arbitrary number of randomly distributed inhomogeneities. In the cases of flat and hyperbolic spaces, the potential is finite at any point, including spatial infinity, and valid for an arbitrary number of gravitating sources. For these two models, investigate the motion of test masses (dwarf galaxies) in the vicinity of one of the inhomogeneities. Show that there is a distance from the inhomogeneity, at which the cosmological expansion prevails over the gravitational attraction and where test masses form the Hubble flow. For a group of galaxies, it happens at a few Mpc and the radius of the zero-velocity sphere is of the order 1 Mpc, which is very close to observations. Outside of this sphere, the dragging effect of the gravitational attraction goes very fast to zero.
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