1203.4570
The halo occupation distribution of SDSS quasars
Richardson, Zheng, Chatterjee, Nagai, Shen
Estimate of the projected 2-pt correlation function (2PCF) of quasars in SDSS over 0.02-120 Mpc/h; combine DR7 on large scales, and Hennawi+ (2006) on small scales; largest spectroscopic quasar clustering sample to date (48k quasars, 0.4<z<2.5, <z>=1.4). Interpret with HOD. Small scale clustering with HOD requires a small fraction (1e-3) of z~1.4 quasars be satellites in DM haloes. At z~1.4, the median masses of the host halos of central and satellite quasars are constrained to be Mcen=4d12 Msun/h and Msat=3.6e14 Msun/h, reqpectively [that has to be a typo on the satellite mass!]. The redshift evolution studied by looking at HOD at z=3.2. Find tentative evidence for an increase in the mass scale of quasar host haloes (14.1e12Msun/h). Cutoff profiles of the mean occupation functions of central quasars reveal that quasar luminosity is more tightly correlated with halo mass at higher redshifts. The average quasar duty cycle around the median host halo mass is inferred to be 7.3e-4 at z~1.4 and 8.6e-2 at z~3.2. Discuss the implications of results for quasar evolution and quasar-galaxy co-evolution.
1203.4571
Direct constraints on the impact of TP-AGB stars on the SED of galaxies from near-infrared spectroscopy
Zibetti, Gallazzi, Charlot, Pasquali, Pierini
Spectro-photometric NIR observations of 16 post-starburst galaxies: test for presence of strong carbon features of TP-AGB stars, predicted by SPS. Selection based on clear spectroscopic optical features indicating strong predominance of stellar populations with ages between 0.5 and 1.5 Gyr and z~0.2; probe spectral region most affected by the carbon features of TP-AGB stars in the evolutionary phase when their IR luminosity is maximum. None of the observed galaxies display such features. NIR fluxes relative to optical are consistent with those predicted by Bruzual & Charlot (2003) models, where the impact of TP-AGB stars is much lower.
1203.4582
The magnetized medium around the radio galaxy B2 0755+37: an interaction with the intra-group gas
Guidetti, Laing, Croston, Bridle, Parma
Magneto-ionic environment of the isolated radio galaxy using detailed imaging of the distributions of Faraday rotation and depolarization of the the radio source with radio and X-ray data. Rotation measure (RM) distribution is complex; evidence for anisotropic fluctuations in two regions. The approaching lobe shows low and uniform RM in an unusual 'stripe' along an extension of the jet axis and a linear gradient transverse to this axis; the leading edge of receding lobe shows arc-like RM structures with sign reversals. Elsewhere, the RM structures are isotropic. The RM power spectra are well described by cut-off power laws with slope 2~3 in different subregions. B-field autocorrelation lengths range from 0.25 to 1.4 kpc. Fluctuations are likely mostly produced by compressed gas and field around the leading edges of the lobs. Identify areas of high depolarization around the jets and inner lobes; could be produced by dense gas immediately surrounding the radio mission containing a B-field which is tangled on small scales. Identify four ways in which the well known depolarization (Faraday depth) asymmetry between jetted and counter-jetted lobes of extended radio sources can be modified by interactions with the surrounding medium.
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