Day 667

Thursday.

1405.6710
Tracing the cosmic velocity field at z~0.1 from galaxy luminosities in the SDSS DR7
Feix, Nusser, Branchini

Probe the cosmic peculiar velocity field out to z~0.1 using spatial modulations in the distribution of observed luminosities, from 5e5 galaxies from SDSS DR7.  r-band LF well represented by a Schechter form.  Bulk flows and higher velocity moments in two z bins, 0.02<z<0.07 and 0.07<z<0.22, agree with the predictions of the LCDM model.  Estimate sigma_8~1.1pm0.4 for the amplitude of the linear matter PS (low accuracy due to small number of galaxies).  While the low-z bin is robust against coherent photometric uncertainties, the bias of results from the second bin is consistent with the ~1% magnitude tilt reported by the SDSS collaboration.  The systematics are expected to have a significantly lower impact in future datasets with larger sky coverage and better photometric calibration.  

1405.6711
Offset active galactic nuclei as tracers of galaxy mergers and supermassive black hole growth
Comerford, Greene

Offset AGNs are AGNs that are in ongoing galaxy mergers, which produce kinematic offsets in the AGNs relative to their host galaxies.  Offset AGNs are also close relatives of dual AGNs.  Conduct a systematic search for offset AGNs in SDSS by selecting AGN emission lines that exhibit statistically significant LoS velocity offsets relative to systemic.  From a parent sample of 18k Type 2 AGNs at z<0.21, identify 351 offset AGN candidates with velocity offsets of 50 km/s<{v} < 410 km/s.  When accounted for projection effects in the observed velocities, estimate that 4-8% of AGNs are offset AGNs.  Design selection criteria to bypass velocity offsets produced by rotation gas disks, AGN outflows, and gravitational recoil of SN BHs, but follow-up observations are still required to confirm candidates as offset AGNs.  Find that the fraction of AGNs that are offset candidates increases with AGN bolometric luminosity, from 0.7% to 6% over the luminosity range 43 < log(L_bol)[erg/s]<46.  If these candidates are shown to be bona mice offset AGNs, then this would be direct observational evidence that galaxy mergers preferentially trigger high-luminosity AGNs.  Finally, find that the fraction of AGNs that are offset AGN candidates increases from 1.9% at z=0.1 to 32% at z=0.7, in step with the growth in the galaxy merger fraction over the same z range.