Day 307

Friday.  ... actually, Sunday.

1209.6055
Mid-infrared selection of active galactic nuclei with the wide-field infrared survey explorer.  II.  Properties of WISE-selected active galactic nuclei in the NDWFS Bo\"otes field
Assef, Stern, Kochanek, ... Brown, Jannuzi, ... et al

Simple criterion of W1(3.4 microns) - W2(4.6 microns) >=0.8 provides a highly reliable and complete AGN sample for W2<15.05: extend study with a wider field, deeper WISE observations than COSMOS field.  Find that the simple color cut loses reliability at fainter fluxes.  Define new selection criterion based on both color and magnitude.  Detection biased towards objects where the AGN dominates the bolometric luminosity output, and can identify highly obscured AGN.  Dust obscuration distribution depend strongly on AGN luminosity: at L~3e44 erg/s, 30% are type 1, while at 4e45 erg/s, the fraction os 65%.   Distribution of obscuration values suggests that dust in the torus is present as both a diffuse medium and in optically thick clouds.

1209.6069
The inhomogeneous reionization of the inter-galactic medium by metal-oor globular clusters
Griffen et al

Reionization by metal-poor globular clusters: GC formation suppressed if local gas is ionized. Possible for metal-poor GCs to have formed via DM halo formation, with truncation at z=10.   Contributions to reioinziation could be as high as 90-98%; in the photon-poorest model, 60-65%.  The surviving clusters in all models have a narrow age range (13.34 Gyr) consistent with curent ages estimates of the MW metal-poor globular clusters.  60% of all metal-poor globular clusters formed at high-z have since been destroyed via tidal interactions with the host galaxy.

1209.6130
Growth of a localized seed magnetic field in a turbulent medium
Cho, Yoo

Study amplification of localized seed B-fields in a turbulent medium; assume driving scale of turbulence comparable to the size of medium.  Find: (1) turbulence can amplify localized seed B-field very efficiently.  (2) Localized seed B-field disperses and fills the whole system very fast.  (3) Growth and turbulence diffusion of a localized seed magnetic field are also fast in high magnetic Prandtl number turbulence [?].  (4) even in decaying turbulence, a localized seed B-field can ultimately fill the whole system.

1209.6135
Solar Cycle 24: is the peak coming?
Sello

The current solar cycle 24 appeared unusual: an unusually extended minimum period, and a global low activity compared to those of the previous 3 or 4 cycles.  ....

1209.6181
Testing homogeneity with the galaxy fossil record
Hoyle, .. Heavens, et al

Homogeneity must be proved inside our past lightcone, while observations take place on the light cone.  The SFH in galaxy fossil record provides a novel way: stack 10 z bin slices of LRG spectra in 12 equal contiguous area; use SFH in a time period which samples the history of the Universe between 11.5 to 13.4 Gyrs (0.2<z<0.5) as a proxy for homogeneity, calculate the posterior distribution for the excess large-scale variance due to inhomogeneity.  Most likely solution is no extra variance at all.

1209.6220
Fitting functions for dark matter density profiles
An, Zhao

Present a unified parameterization of the fitting functions of density profiles of DM haloes or elliptical galaxies.  Notable: classical Einasto profile appears naturally as the continuous limiting case of the cored subfamily amongst the double power-law profiles of Zhao (1996).  There is basically no qualitative difference between halo models well-fitted by the Einasto profile and NFW model.  

1209.6231
Revealing a strongly reddened, faint active galactic nucleus population by stacking deep co-added images
Varga, Csabai, Dobos

More than 50% of radio objects have not been detected by wide-field optical surveys.  Aim: detect optical emission from unresolved, isolated radio sources of VLA faint images of FIRST survey have no identified optical counterparts in SDSS stripe 82.  2116 such radio point sources selected; cut-out images from stripe 82 generated; then stacked again to obtain images of high S/N ratio, in the hope that optical emission from radio sources would become detectable.  Resulting stacked images show central peaks similar to point sources, have very red colors with steep optical spectral energy distributions.  Total integration time: ~300h, with corresponding 5 sig detection limit at r = 26.6 mag,vprobably mostly from the central regions of dust-reddenedd Type 1 active galactic nuclei.