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Astrophysics, Gravitation and Cosmology Seminar: "Dark matter halo bias from separate universe simulations"

Event Type
Department of Physics
464 Loomis
Apr 26, 2017   12:00 pm  
Titouan Lazeyras, PhD student (of Fabian Schmidt) at MPA, Garching bei Muenchen , Germany
Betsy Greifenkamp
Originating Calendar
Physics - Astrophysics, Gravitation, and Cosmology Seminar

The large-scale local bias parameters of dark matter halos are essential to describe the statistics of halos and galaxies on large scales, as well as for the halo model of the matter distribution. Using so-called separate universe simulations, we recently obtained precise measurements of the three leading bias parameters. For b2 and b3, these are the most precise measurements to date. We compare our results with bias parameters obtained from two and three points cross-correlation functions and with theoretical predictions from the excursion set peaks (ESP) model.

Using the same set of simulations, we further investigate halo assembly bias, i.e. the dependence of the halo bias on properties other than the halo mass. We focus on several halo properties including halo concentration, spin, ellipticity and mass accretion rate and measure assembly bias for both b1 and b2. Results are in good agreement with previous studies for the linear bias. To try and better understand the physical mechanisms behind assembly bias, we also look at the joint dependence of bias on two halo properties in addition to the mass and compare our results to theoretical ones from the ESP.


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