Gamma-ray Signal from Earth-mass Dark Matter Microhalos - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




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Abstract: Earth-mass dark matter microhalos with size of ~100 AUs are the firststructures formed in the universe, if the dark matter of the Universe are madeof neutralino. Here, we report the results of ultra-high-resolution simulationsof the formation and evolution of these microhalos. We found that microhaloshave the central density cusps of the form $ ho \propto r^{-1.5}$, muchsteeper than the cusps of larger dark halos. The central regions of thesemicrohalos survive the encounters with stars except in very inner region of thegalaxy down to the radius of a few hundreds pcs from the galactic center. Theannihilation signals from nearest microhalos are observed as gamma-raypoint-sources radius less than 1-, with unusually large proper motions of~0.2 degree per year. Their surface brightnesses are ~10% of that of thegalactic center. Their S-N ratios might be better if they are far from thegalactic plane. Luminosities of subhalos are determined only by their mass, andthey are more than one order of magnitude luminous than the estimation bySpringel et al. 2008: A boost factor can be larger than 1000. Perturbationsto the millisecond pulsars by gravitational attractions of nearby earth-massmicrohalos can be detected by the observations of Parkes Pulsar Timing ArrayPPTA.



Autor: Tomoaki Ishiyama, Junichiro Makino, Toshikazu Ebisuzaki

Fuente: https://arxiv.org/







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