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arXiv · 0810.3674

On the Origin of the 511 keV Emission in the Galactic Centre

Reba M. Bandyopadhyay·Joseph Silk·James E. Taylor·Thomas J. Maccarone
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Abstract

Diffuse 511 keV line emission, from the annihilation of cold positrons, has been observed in the direction of the Galactic Centre for more than 30 years. The latest high-resolution maps of this emission produced by the SPI instrument on INTEGRAL suggest at least one component of the emission is spatially coincident with the distribution of ~70 luminous, low-mass X-ray binaries detected in the soft gamma-ray band. The X-ray band, however, is generally a more sensitive probe of X-ray binary populations. Recent X-ray surveys of the Galactic Centre have discovered a much larger population (>4000) of faint, hard X-ray point sources. We investigate the possibility that the positrons observed in the direction of the Galactic Centre originate in pair-dominated jets generated by this population of fainter accretion-powered X-ray binaries. We also consider briefly whether such sources could account for unexplained diffuse emission associated with the Galactic Centre in the microwave (the WMAP `haze') and at other wavelengths. Finally, we point out several unresolved problems in associating Galactic Centre 511 keV emission with the brightest X-ray binaries.

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Reba M. Bandyopadhyay, Joseph Silk, James E. Taylor, Thomas J. Maccarone. 2008-10-20. On the Origin of the 511 keV Emission in the Galactic Centre. https://doi.org/10.1111/j.1365-2966.2008.14113.x

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