1704.07837
Biases from neutrino bias: to worry or not to worry?
Raccanelli, Verde, Villaescusa-Navarro
The relation between the halo field and the matter fluctuation (halo bias), in the presence of massive neutrinos depends on the total neutrino mass, massive neutrinos introduce an additional scale-dependence on the bias which is usually neglected in cosmological analysis. Investigate the magnitude of the systematic effect on interesting cosmological parameters induced by neglecting this scale dependence, finding that while it is not a problem for current surveys, it is non-negligible for future, denser or deeper ones depending on the neutrino mass, the maximum scale used for the analyses and the details of the nuisance parameters considered. However there is a simple recipe to account for the bulk of the effect as to make it fully negligible, which is illustrated, and advocate that it should be included in analysis of forthcoming large-scale structure surveys.
1704.07847
A first constraint on the average mass of ultra diffuse galaxies from weak gravitational lensing
Sifón, van der Burg, Hoekstra, Muzzin, Herbonnet
The recent discovery of thousands of UDGs in nearby galaxy clusters has opened a new window into the process of galaxy formation and evolution. Several scenarios have been proposed to explain the formation history of UDGs ,and their ability to survive in the harsh cluster environments. A key requirement to distinguish between these scenarios is a measurement of their halo masses which, due to their low surface brightnesses, has proven difficult if one relies on stellar tracers of the potential. Exploit WL, a technique that does not depend on these baryonic tracers, to measure the average sub halo mass of 784 UDGs selected in 18 clusters at z<0.09. The sample of UDGs has a median stellar mass <m*>=2e8 Msun and median effective radius <r_eff>=2.8 kpc. Constrain the average mass of sub haloes within 30 kpc to log m_UCG(r<30kpc)/M_sun < 10.99 at 95% CL, implying an effective viral mass log m_200/M_sun <=11.80, and a lower limit on the stellar mass fraction within 10kpc of 1.0%. Such mass is consistent with a simple extrapolation of the subhalo-to-stellar mass relation of typical satellite galaxies in massive clusters. However, the analysis is not sensitive to scatter about this mean mass; the possibility remains that extreme UDGs reside in haloes as massive as the MW.
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