1608.06938
The impact of baryonic physics on the sub halo mass function and implications for gravitational lensing
Despali, Vegetti
Investigate the impact of baryonic physics on the sub halo population by analyzing the results of 2 recent hydrosims (EAGLE and Illustris) which have very similar configuration but a different model of baryonic physics. Concentrate on haloes with a mass between 1e12.5 and 14 Msun/h and 0.2<z<0.5, comparing with observational results and subhalo detections in early-type galaxy lenses. Compare the number and the spatial distribution of sub haloes in the fully hydro runs and in their DM only counterparts, focusing on the differences between the 2 simulations. Find that the presence of baryons reduces the number of sub haloes, especially at the low mass end (<1e10 Msun/h), by different amounts depending on the model. The variations in the sub halo mass function are strongly dependent on those in the halo mass function, which is shifted by the effect of stellar and AGN feedback: a lower number of low mass haloes available for accretion in the first place; then additional differences can be attributed to the action of baryonic physics inside the halo. Finally, search for analogues of the observed lenses (SLACS) in the simulations, doing a selection in velocity dispersion and dynamical properties. Use the selected galaxies to quantify detection expectations based on the sub halo populations in the different simulations, calculating the detection probability and the predicted values for the DM fraction in sub haloes f_DM and the slope of the mass function alpha.
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