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arXiv · 1803.04370

Galactic Binaries Can Explain the Fermi Galactic Center Excess and 511 keV Emission

Richard Bartels·Francesca Calore·Emma Storm·Christoph Weniger
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Abstract

The Fermi-LAT Galactic Center excess and the 511 keV positron-annihilation signal from the inner Galaxy bare a striking morphological similarity. We propose that both can be explained through a scenario in which millisecond pulsars produce the Galactic Center excess and their progenitors, low-mass X-ray binaries, the 511 keV signal. As a proof-of-principle we study a specific population synthesis scenario from the literature involving so-called ultracompact X-ray binaries. Moreover, for the first time, we quantitatively show that neutron star, rather than black hole, low-mass X-ray binaries can be responsible for the majority of the positrons. In this particular scenario binary millisecond pulsars can be both the source of the Fermi-LAT $\gamma$-ray excess and the bulge positrons. Future avenues to test this scenario are discussed.

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Richard Bartels, Francesca Calore, Emma Storm, Christoph Weniger. 2018-03-12. Galactic Binaries Can Explain the Fermi Galactic Center Excess and 511 keV Emission. https://doi.org/10.1093/mnras%2Fsty2135

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