Galactic binaries can explain the Fermi Galactic centre excess and 511 keV emission
Abstract
The Fermi-LAT Galactic Centre excess and the 511 keV positron-annihilation signal from the inner Galaxy bear a striking morphological similarity. We propose that both can be explained through a scenario in which millisecond pulsars produce the Galactic Centre 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 γ-ray excess and the bulge positrons. Future avenues to test this scenario are discussed.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- November 2018
- DOI:
- 10.1093/mnras/sty2135
- arXiv:
- arXiv:1803.04370
- Bibcode:
- 2018MNRAS.480.3826B
- Keywords:
-
- gamma-rays : general;
- Galaxy : bulge;
- pulsars : general;
- stars : jets;
- X-rays : binaries;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 11 pages, 5 figures, appendix, comments welcome