Day 708

Friday.

Nature
Velocity anti-correlation of diametrically opposed galaxy satellites in the low-redshift Universe
Ibata, et al

In the local universe (z<0.05), pairs of satellite galaxies diametrically opposed and within 150 kpc form the galactic center show aniti-correlation in their velocities at high sigma.  Also, the distribution of galaxies in the larger-scale (out to distances of about 2 Mpc) is strongly clumped along the axis joining they inner satellite pair (>7 sigma).  This may indicate that planes of co-rotating satellites, similar to those seen around Andromeda, are ubiquitous, and their coherent motion suggests that they represent a substantial repository of angular momentum on scales of about 100 kpc.

1407.6363
The odd couple: quasars and black holes
Tremaine

Quasars emit more energy than any other objects in the universe, yet are not much bigger than the solar system.  We are almost certain that quasars are powered by giant BHs of up to 10e10 times the mass of the Sun, and that BHs of between 1e6 and 1e10 Msun---dead quasars---are present at the centers of most galaxies.  Our own galaxy contains a BH of 4.3e6 Msun.  The mass of the central BH appears to be closely related to other properties of its host galaxy, such as the total mass in stars, but the origin of this relation and the role that BHs play in the formation of galaxies are still a mystery.

1407.6370
A correlation between hard gamma-ray sources and cosmic voids along the line of sight
Furniss, Sutter, Primack, Dominiquez

At the 2.4 sigma level.  Less suggestive correlation for the Fermi hard source population (1.7 sigma).  The preference for under dense sight lines is not displayed by gamma-ray emitting galaxies within the second Fermi catalog, containing sources detected above 100 MeV, or the SDSS DR7 quasar catalog.  Investigate wether this marginal correlation might be a result of  lower extragalactic background light photon density within the under dense regions and find that, even in the most extreme case of a entirely under dense sight line, the EBL photon density is only 2% less than the nominal EBL density.  This translates into gamma-ray attention of <10%, unable to account for the apparent hard source correlation with under dense LoS.