On the nature of the EGRET source at the galactic center

Sera Markoff, Fulvio Melia, Ina Sarcevic

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

The recent detection of a γ-ray flux from the direction of the Galactic center by EGRET on the Compton GRO raises the question of whether this is a point source (possibly coincident with the massive black hole candidate Sgr A*) or a diffuse emitter. Using the latest experimental particle physics data and theoretical models, we examine in detail the γ-ray spectrum produced by synchrotron, inverse Compton scattering, and mesonic decay resulting from the interaction of relativistic protons with hydrogen accreting onto a point-like object. Such a distribution of high-energy baryons may be expected to form within an accretion shock as the inflowing gas becomes supersonic. This scenario is motivated by hydrodynamic studies of Bondi-Hoyle accretion onto Sgr A*, which indicate that many of its radiative characteristics may ultimately be associated with energy liberated as this plasma descends into the deep potential well. Earlier attempts to analyze this process concluded that the EGRET data are inconsistent with a massive point-like object. Here we demonstrate that a more careful treatment of the physics of p-p scattering suggests that a black hole of ∼106 M may be contributing to this high-energy emission.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume489
Issue number1 PART II
StatePublished - 1997

Fingerprint

rays
physics
accretion
scattering
energy
point sources
point source
baryons
synchrotrons
emitters
hydrodynamics
shock
hydrogen
plasma
protons
decay
gases
gas
interactions
detection

Keywords

  • Acceleration of particles
  • Black hole physics
  • Galaxies: nuclei
  • Galaxy: center gamma rays: theory
  • Radiation mechanisms: nonthermal

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

On the nature of the EGRET source at the galactic center. / Markoff, Sera; Melia, Fulvio; Sarcevic, Ina.

In: Astrophysical Journal, Vol. 489, No. 1 PART II, 1997.

Research output: Contribution to journalArticle

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