A new paper led by undergraduate thesis student Benjamin Lehmann and graduate student Yao-Yuan Mao. We present a new method for abundance matching galaxies to dark matter halos, which includes a free parameter that can account for the concentration dependence of the galaxy-halo connection, and thus naturally can account for different levels of assembly bias. We show that this parameter can be constrained with clustering data, and that low redshift clustering measurements from SDSS prefer a moderate amount of concentration dependence --- more than would be indicated by matching galaxy luminosity to the peak halo mass, and less than would be indicated by matching to the peak halo circular velocity. We use new large high-resolution simulation boxes to show that statistical constraints on these models have been limited primarily by sample variance in the limited-size simulations, and not in the data.
See more here: http://arxiv.org/abs/1510.05651
Scientists on the Dark Energy Survey, using one of the world’s most powerful digital cameras, have discovered eight more faint celestial objects hovering near our Milky Way galaxy. Signs indicate that they—like the objects found by the same team earlier this year—are likely dwarf satellite galaxies, the smallest and closest known form of galaxies.
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