Day 870

Monday.


1504.04372
Satellites of LMCs: close friendships ruined by Milky Way Mass Halos
Deason, Wentzel, Garrison-Kimmel, Belokurov

Motivated by the recent discovery of several dwarf galaxies near the LMC, study the accretion of massive satellites onto MW/M31-like halos using the ELVIS suite of N-body simulations.  Identify 25 surviving subhalos near the expected mass of the LMC, and investigate the lower-mass satellite that were associated with these subclass before they fell into the MW/M31 halos.  Typically, 7% of the overall z=0 satellite population of MW/M31 halos were in a surviving LMC-group poor to falling into the MW/M31 halo.  This fraction, however, can vary between 1% and 25% being higher for groups with higher-mass and/or more recent infall times.  Groups of satellite disperse rapidly in phase space after infall, and their distances and velocities relative to the group center become statistically similar to the overall satellite population after 4-8 Gyr.  Quantify the likelihood that satellites were associated with an LMC-mass group as a function of both distance and velocity relative to the LMC at z=0.  The close proximity in distance of the nine DES candidate dwarf galaxies to the LMC suggest that ~2-4 are likely associated with the LMC.   Furthermore, if several of these dwarfs nearby to the LMC are genuine members, then the LMC-group probably fell into the MW very recently, 2Gyr ago.  If the connection with the LMC is established with the hope of the follow-up velocity measurements, these "satellites of satellites" represent prime candidates to study the affects of group pre-processing on lower mass dwarfs.


1504.04516
The clustering evolution of dusty star-forming galaxies
Cowley, Lacey, Baugh, Cole

Present predictions for the clustering of galaxies selected by their total L_IR, and their emission at FIR and sub-mm wavelengths.  Combine a new version of the GALFORM SAM of galaxy formation, implemented in a Millennium-style N-body simulation utilizing the WMAP7 cosmology, with a self-consistent model for calculating the absorption and re-emission of stellar radiation by dust.  In the model, galaxies selected at 850 um predominantly reside in DM haloes of mass 1e11.5-12 Msun/h, independent of z for 0.2<z<4 or flux (for 0.25<S_850um<4 mJy).  Around the peak of their redshift distribution (z~2.5) the brightest galaxies (S_850um>4 mJy) exhibit a correlation length of r_0=5.5+0.3-0.5 Mpc/h, consistent with observations.  Show further that these galaxies evolve into z=0 descendants with stellar mass ~1e11 Msun/h occupying haloes which span a broad range in mass ~1e12-14 Msun/h.  The FIR emissivity at shorter wavelengths (250, 350, and 500 um) in the model is dominated by galaxies in the same halo mass range, again independent of z for 0.5<z<5.  Compare the predictions of the angular power spectrum of Cosmic Infrared Background (CIB) anisotropies at these wavelengths with recent observations, and find that the model agrees with the observed power to within a factor of ~2 over all scales and wavelengths, an improvement over earlier versions of the model.  Simulating sub-mm imaging at 850 um, show that source confusion due to the coarse angular resolution of single-dish telescopes at this wavelength can significantly bias angular clustering measurements  severely complicating the interpretation of such observations.