Day 598

Thursday.  Karnaval!  (Not going.)

1402.6319
A globular cluster toward M87 with a radial velocity < -1000 km/s: the first hypervelocity cluster
Caldwell, Strader, Romanowsky, Brodie, Moore, Diemand, Martizzi

An object near M87 in the Virgo Cluster with offset of >2300 km/s from systemic velocity  (blueshift of 1025 km/s).  Photometric and spectroscopic data provide strong evidence that this object is a distant massive globular cluster ("HVGC-1").  Disfavor system of stars bound to a recoiling BH.  The odds of observing an outlier as extreme as HVGC-1 in a virialized distribution of intracluster objects are small; it appears more likely that the cluster was (or is being) ejected from Virgo following a 3-body interaction.  The nature of the interaction is unclear, and could involve either a sub halo or a binary SMBH at the center of M87.

1402.6325
Grain physics and IR dust emission in AGN environments
Hensley, Ostriker, Ciotti

Study effects of dust physics on the properties and evolution of early type galaxies containing central BHs, as determined by AGN feedback.  Find that during cooling flow episodes, radiation pressure on the dust in and interior to infalling shells of cold gas can greatly impact the amount of gas able to be accreted and therefore the frequency of AGN bursts.  However, the overall hydrodynamic evolution of all models, including mass budget, is relatively robust to the assumptions on dust.  The most detailed models find that the dust to metals ratio is reduced by factors of 1e-1 to 1e-2 relative to MW abundances, and in quiescent phases the dust content of the galaxy would result in ~0.03 magnitudes of extinction to the center of the galaxy.  Find that IR re-emission from hot dust can dominate the bolometric luminosity of the galaxy during the early stages of an AGN burst, reaching values in excess of 1e46 erg/s.  The AGN-emitted UV is largely absorbed, but the optical depth in the IR does not exceed unity, so the radiation momentum input never exceeds L_BH/c.  Constrain the viability of the models by comparing the energy output in each band, AGN duty cycle, FIR emission, dust mass and opacity, BH mass, and other model predictions to current observations.  These constraints force models wherein the destruction of dust in hot gas by sputtering and the competing growth of dust in cold gas results in depletion at the 1e-2  level, and only models with a dynamic dust to gas ratio are able to produce both quiescent galaxies consistent with observations and high obscured fractions during AGN "on" phases.  During AGN outbursts, predict that a large fraction of the FIR luminosity can be attributed to warm dust emission (~100K) from dense dusty gas within <1kpc reradiating the AGN UV emission.

1402.6326
Characterizing the best cosmic telescopes with the millennium simulations
French, … Zabludoff, Keeton, … et al

Characterize LoS which maximize the number of lensed z~10 galaxies with "entendue" sigma_mu, the area in the source plane magnified over some threshold mu.  Use sims to determine the frequency of high sigma_mu beams on the sky, their properties, and efficient selection criteria.  Define the best beams as having sigma_{mu>3}>2000 arcsec^2, for a z~10 source plane, and predict 477pm21 such beams on the sky.  The total mass in the beam and sigma_{mu>3} are strongly correlated.  After controlling for total mass, find a significant residual correlation between sigma_{mu>3} and the number of cluster-scale haloes (1e14 Msun/h) in the beam.  Beams with sigma_{mu>3}>2000 arcsec^2 are 10x more likely to contain multiple cluster-scale halos than a single cluster-scale halo.  Beams containing A1689-like massive cluster halo often have additional structures along the LoS, including at least one additional cluster-scale (M200>1e14 Msun/h) halo 28% of the time.  Selecting beams with multiple, massive structures will lead to enhanced detection of the most distant and intrinsically faint galaxies.

1402.6335
A submillimeter galaxy illuminating its circumgalactic medium: Ly-alpha scattering in a cold, clumpy outflow
Geach et al

A 100kpc-scale radio-quiet emission-line nebula at z=3.1 (a "Lyman alpha blob").  Flux density of source implies the presence of a galaxy (or a group of galaxies) with L~1e12 L_sun.  The position of an active source at the center of a ~50kpc-radius ring of linearly polarized Lya emission detected suggests that the central source is leaking Lya photons preferentially in the plane of the sky, which undergo scattering in HI clouds at large galactocentric radius.  The Lya morphology around the sub millimeter detection is reminiscent of biconical outflow, and the average Lya line profiles of the two lobes are dominated by a red peak, expected for a resonant line emerging from a medium with a bulk velocity gradient that is outflowing relative to the line center.  Taken together, these observations provide compelling evidence that the central active galaxy (or galaxies) is responsible for a large fraction of the extended Lya emission and morphology.  Less clear is the history of the cold gas in the circumgalactic medium being traced by Lya: is it mainly pristine material accreting into the halo that has not yet been processed through an ISM, now being blown back as it encounters an outflow, or does it mainly comprise gas that has been sept-up within the ISM and expelled from the galaxy?

1402.6470
Structure and morphology of X-ray selected AGN hosts at 1<z<3 in CANDELS-COSMOS field
Fan et al

35 X-ray selected AGNs at z~2 in COSMOS; compare to 350 control sample galaxies.  GALFIT on surface brightness profile show that the distribution of Sersic index n of AGN hosts does not show a statistical difference from that of the control sample.  All distributions of other structural parameters (asymmetry index, Gini coefficient, concentration index and M20 index) are consistent with those on the control sample.  No significant difference in the distortion fractions between the AGN host sample and control sample.  Conclude that the morphologies of X-ray selected AGN hosts are similar to those of nonactive galaxies and most AGN activity is not triggered by major merger.