------------------------------------------------------------------------ gc511.tex, MNRAS, 2009, vol. 392 Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-MailScanner-Information: Please contact the postmaster@aoc.nrao.edu for more information X-MailScanner: Found to be clean X-MailScanner-SpamCheck: not spam, SpamAssassin (not cached, score=-4, required 5, autolearn=disabled, RCVD_IN_DNSWL_MED -4.00) X-MailScanner-From: reba@astro.ufl.edu X-Spam-Status: No %astro-ph/0810.3674 \begin{document} \title[511 keV Emission in the Galactic Centre] {On the Origin of the 511 keV Emission in the Galactic Centre} \author[Bandyopadhyay, Silk, Taylor \& Maccarone] {Reba M. Bandyopadhyay$^{1}$\thanks{email: {\tt reba@astro.ufl.edu}}, Joseph Silk$^{2}$, James E. Taylor$^{3}$ and Thomas J. Maccarone$^ {4}$\\ $^{1}$Department of Astronomy, 211 Bryant Space Science Centre, Gainesville, FL 32611-2055 USA\\ $^{2}$Department of Astrophysics, Denys Wilkinson Building, 1 Keble Road, Oxford OX1 3RH, UK\\ $^{3}$Department of Physics \& Astronomy, 200 University Avenue West, Waterloo, Ontario, N2L 3G1 Canada\\ $^{4}$School of Physics \& Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ, UK} \date{\today} \pubyear{2007} \maketitle \begin{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 $\sim$70 luminous, low-mass X-ray binaries detected in the soft gamma-ray band. The X-ray band, however, is generally a more sensitive probe of X-ray binary populations. Recent X-ray surveys of the Galactic Centre have discovered a much larger population ($>$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 {\it 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. \end{abstract} \begin{keywords} {\it dark matter; compact objects; X-ray binaries; Galactic Centre; accretion, accretion physics; jets} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -- Dr. Reba M. Bandyopadhyay EMAIL: reba@astro.ufl.edu Assistant Scientist reba@alum.mit.edu Department of Astronomy dr.reba@gmail.com University of Florida reba@xeus.nrl.navy.mil 211 Bryant Space Science Centre PHONE: +1-352-392-2052, ext. 232 Gainesville, FL 32611-2055 USA WWW: http://www.astro.ufl.edu/~reba/