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Abstract: We employ numerical simulations and simple analytical estimates to argue thatdark matter substructures orbiting in the inner regions of the Galaxy can beefficiently destroyed by disk shocking, a dynamical process known to affectglobular star clusters. We carry out a set of fiducial high-resolutioncollisionless simulations in which we adiabatically grow a disk, allowing us toexamine the impact of the disk on the substructure abundance. We also track theorbits of dark matter satellites in the high-resolution Aquarius simulationsand analytically estimate the cumulative halo and disk shocking effect. Ourcalculations indicate that the presence of a disk with only 10% of the totalMilky Way mass can significantly alter the mass function of substructures inthe inner parts of halos. This has important implications especially for therelatively small number of satellites seen within ~30 kpc of the Milky Waycenter, where disk shocking is expected to reduce the substructure abundance bya factor of ~2 at 10^9 M$ {\odot}$ and~3 at 10^7 M$ {\odot}$. The most massive subhalos with 10^10M$ {\odot}$ survive even in the presence of the disk. This suggests thatthere is no inner missing satellite problem, and calls into question whetherthese substructures can produce transient features in disks, like multi-armedspiral patterns. Also, the depletion of dark matter substructures throughshocking on the baryonic structures of the disk and central bulge may aggravatethe problem to fully account for the observed flux anomalies in gravitationallens systems, and significantly reduces the dark matter annihilation signalexpected from nearby substructures in the inner halo.



Author: Elena D'Onghia 1, Volker Springel 2, Lars Hernquist 1, Dusan Keres 1 1 Harvard-Cfa, 2 MPA, Garching

Source: https://arxiv.org/







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