Day 418

Tuesday.

1304.5537
The HETDEX pilot survey.  IV.  The evolution of [O II] emitting galaxies frorm z~0.5 to z~0
Ciardullo et al

Emission-line flux, and de-reddened [O II] 3727 luminosity; calculate total SFR.  Show that over the last ~5 Gyr of cosmic time there has been substantial evolution in the [OII] emission line luminosity function, with L* decreasing by ~0.6pm0.2 dex in the observed function, and by ~0.9pm0.2 dex in the de-reddened relation.  Accompanying this decline is a significant shift in the distribution of [OII] equivalent widths, with the fraction of high equivalent-width emitters declining dramatically with time.  Overall, the data imply that athe relative intensity of SF within galaxies has decreased over the past ~5 Gyr, and that the SFR density of the universe has declined by a factor of ~2.5 between z~0.5 and 0.  

1304.5557
The dark side of galaxy color
Hearin, Watson

"Age distribution matching": a new theoretical formalism for predicting how galaxies of luminosity L and color C occupy dark matter haloes.  Model supposes that there are just two fundamental properties of a halo that determine the color and brightness of the galaxy it hosts: the maximum circular velocity Vmax, and the redshift at which the galaxy will be starved of cold gas z_starve.  The halo property z_starve is intended to encompass physical characteristics of a halo's mass assembly history (MAH) that may deprive the galaxy of its cold gas supply and, ultimately, quench its star formation.  These include the epochs when: (a) a halo accretes onto a large halo, z_acc, (b) a halo reaches a characteristic mass (~1e12 Msun/h), z_char, and (c) a halo transitioned from the fast- to slow-accretion regime, z_form.  A halo's z_starve value is determined by whichever of these events happens first in its MAH.  The new, defining feature of the model is that, at fixed L, galaxy color is in monotonic correspondence with z_starve with the larger values of z_starve being assigned redder colors.  Populate the Bolshoi N-body simulation with a mock galaxy catalog based on age distribution matching, and show that the resulting mock galaxy distribution accurately describes the luminosity- and color-binned two-point correlation function of galaxies in SDSS, as well as a variety of low-redshift galaxy group statistics.  Study of the property z_starve has important implications for how halo MAH influences stellar mass assembly.  For example, the significance of the epoch z_form suggests a new, independent channel for so-called "mass quenching" based on the rate of halo mass accretion.  Make publicly available the low-z, SDSS Mr<-19 mock galaxy catalog, and main progenitor histories of all z=0 Bolshoi halos.

1304.5573
Mean spectral energy distributions and bolometric corrections for luminous quasars
Krawczyk, Richards, Mehta, Vogeley, ... Ross, Schneider

UV to MIR SEDs of 119k luminous broad-lined quasars with 0.064<z<5.46 from Spitzer and WISE (MIR), 2MASS and UKIDSS (NIR), SDSS (optical), and GalEx (UV).  The mean SED requires a bolometric correction (relative to 2500A) of BC=2.75pm0.40 using the integrated light from 1um-2keV, and further explore the range of bolometric corrections for each object.  Investigate the dependence of the mean SED on various parameters, particularly the UV luminosity for quasars with 0.5<z<3 and the properties of the UV emission lines for quasars with z>1.6; the latter is a possible indicator of the strength of the accretion disk wind, which is expected to be SED dependent.  L-dependent mean SEDs show that, relative to the high-L SED, low-L SEDs exhibit a harder FUV spectral slope, a redder optical continuum, and less host dust.  Mean SEDs constructed instead as a function of UV emission line properties reveal changes that are consistent with known PCA trends.  A potentially important contribution to the bolometric correction is the unseen E-UV continuum.  Lower-L quasars and/or quasars with disk-dominated broad emission lines may require an extra continuum component in the EUV that is not present in high-L quasars with strong accretion disk winds.  Consider 4 possible models and explore the resulting bolometric corrections.  Important to accurate determination of quasar accretion rates.

1304.5738
Microlensing in globular clusters: the first confirmed lens
Jetzer

As the title says.