Hostname: page-component-78c5997874-t5tsf Total loading time: 0 Render date: 2024-11-14T20:43:14.019Z Has data issue: false hasContentIssue false
  • English
  • Français

Low Energy Galactic Center Gamma Rays from Low Mass X-Ray Binaries

Published online by Cambridge University Press:  23 September 2016

W. Kluźniak ,
M. Ruderman ,
J. Shaham  and
M. Tavani
W. Kluźniak
Affiliation:
Department of Physics and Astrophysics Laboratory Columbia University, New York, N.Y. 10027
M. Ruderman
Affiliation:
Department of Physics and Astrophysics Laboratory Columbia University, New York, N.Y. 10027
J. Shaham
Affiliation:
Department of Physics and Astrophysics Laboratory Columbia University, New York, N.Y. 10027
M. Tavani
Affiliation:
Department of Physics and Astrophysics Laboratory Columbia University, New York, N.Y. 10027

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The hard X-ray and low energy γ-ray emission from the galactic center region (GCR) has four components: a power-law continuum between 20/50 keV and 200/300 keV with a power-law photon index β in the range ~ 2.5 to ~ 3.1; a harder spectrum with β ~ 1.–1.5 between 200/300 keV and ~ 511 keV; a narrow electron-positron annihilation line at 511 keV, reported to disappear in less than < 1/2 yr, although the temporal variation is controversial; and an equally variable continuum emission between 511 keV and several MeV (“MeV bump”). All four have luminosities 1037–1038 erg s−1, if they are located 10 kpc away. We propose non-thermal processes in low mass X-ray binaries (LMXB's) concentrated in the galactic bulge as the direct source of the three continuum components of the emission, as well as of an escaping electron-positron e± wind whose positron annihilation relatively far from the star could be the source of the 511 keV line. We consider a model for energetic emission from LMXB's that reproduces the softer power-law component of the GCR continuum through synchrotron emission of relativistic electrons in the strongly non-uniform (dipolar) magnetic field of the neutron star. We also explain, with less confidence, the variable MeV bump as the result of interaction of harder γ-rays with the power-law photons. The harder power law might be due to Compton scattering of relativistic electrons or photons.

Type
The High - Energy View
Information
Symposium - International Astronomical Union , Volume 136: The Galactic Center , 1989 , pp. 627 - 632
Copyright
Copyright © Kluwer 1989 

References

[1] Riegler, G.R., Ling, J.C., Mahoney, W.A., Wheaton, W.A., and Jacobson, A.S. in Positron-Electron Pairs in Astrophysics , eds. Burns, M. L., Harding, A. K. and Ramaty, R., AIP Conference Proceedings No. 101 (New York: AIP), pp. 230–236 (1983).Google Scholar
[2] Riegler, G.R., Ling, J.C., Mahoney, W.A., Wheaton, W.A., and Jacobson, A.S., Ap. J. (Letters) , 294, L13–L15 (1985).CrossRefGoogle Scholar
[3] Riegler, G.R. et al., Ap. J. (Letters) , 248, L13–L16 (1981).Google Scholar
[4] Leventhal, M., MacCallum, C.J., Huters, A.F., and Stang, P.D., Ap. J. (Letters) , 260, L1–L5 (1982).Google Scholar
[5] Share, G.H., Kinzer, R.L., Kurfess, J.D., Messina, D.C., Purcell, W.R., Chupp, E.L., Forrest, D.J., and Reppin, C., Ap. J. , 326, 717–732 (1988).Google Scholar
[6] Skinner, G. K. et al., Nature , 330, 544–547 (1987) and this Symposium. Google Scholar
[7] Cook, W. R. et al., this Symposium. Google Scholar
[8] Lingenfelter, R. E. and Ramaty, R. in The Galactic Center , ed. Riegler, G. R. and Blandford, R. D., AIP Conference Proceedings No. 83 (New York: AIP), pp. 148–159 (1982).Google Scholar
[9] Ruderman, M., Shaham, J., Tavani, M., and Eichler, D., 1987, “Late Evolution of Very Low Mass X-ray Binaries Sustained by Gamma-Rays from their Primaries”, Ap. J. , in press.Google Scholar
[10] Ruderman, M., in Proc. NATO ASI High Energy Phenomena around Collapsed Stars , ed. Pacini, F. (Norwell, Mass.: Reidel), p. 145– (1986).Google Scholar
[11] Gorham, P.W. et al., Ap. J. , 309, 114–121 (1986).Google Scholar
[12] Lamb, R.C. in 13th Texas Symposium of Relativistic Astrophysics , ed. Ulmer, M. P. (Singapore: World Scientific), pp. 589–594 (1987).Google Scholar
[13] Leventhal, M., MacCallum, C.J., and Stang, P.D., Ap. J. (Letters) , 225, L11–L14 (1982).Google Scholar
[14] Maurer, G.S., Johnson, W.N., Kurfess, J.D., and Strickman, M.S., Ap. J. , 254, 271–278 (1982).Google Scholar
[15] White, N.E. and Holt, S.S., Ap. J. , 257, 318–337 (1982).CrossRefGoogle Scholar
[16] Levine, A.M. et al., Ap. J. Supp. , 54, 581– (1984).Google Scholar
[17] Knight, F.K., Johnson, W.N., Kurfess, J.D., and Strickman, M.S., Ap. J. , 290, 557–567 (1985).Google Scholar
[18] White, N.E. and Mason, K.O., Sp. Sci. Rev. , 40, 167– (1985).CrossRefGoogle Scholar
[19] White, N.E., Stella, L. and Parmar, A.N., Ap. J. , 324, 363– (1987).Google Scholar