Detection of hard X-ray emission from the Galactic nuclear region with INTEGRAL

G. Belanger, A. Goldwurm, P. Goldoni, Joachim Paul, R. Terrier, M. Falanga, P. Ubertini, A. Bazzano, M. Del Santo, C. Winkler, A.N. Parmar, E. Kuulkers, K. Ebisawa, J.P. Roques, Niels Lund, F. Melia

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Abstract

This Letter presents the first results of an observational campaign to study the Galactic center with INTEGRAL, the International Gamma-Ray Astrophysics Laboratory. Mosaicked images were constructed using data obtained with ISGRI, the soft gamma-ray instrument of the coded aperture IBIS imager, in the energy ranges 20 - 40 and 40 - 100 keV. These give a yet unseen view of the high-energy sources of this region in hard X-rays and gamma rays with an angular resolution of 12' (FWHM). We report on the discovery of a source, IGR J1745.6 - 2901, coincident with the Galactic nucleus Sgr A* to within 0.'9. Located at R.A. = 17(h)45(m)38(s).5 (J2000.0), decl. = -29degrees01'15"(J2000.0), the source is visible up to about 100 keV with a 20 - 100 keV luminosity at 8 kpc of (2.89 +/- 0.41) x 10(35) ergs s(-1). Although the new INTEGRAL source cannot unequivocally be associated to the Galactic nucleus, this is the first report of significant hard X-ray emission from within the inner 10' of the Galaxy and a contribution from the Galactic supermassive black hole itself cannot be excluded.
Original languageEnglish
JournalAstrophysical Journal
Volume601
Issue number2
Pages (from-to)L163-L166
ISSN0004-637X
Publication statusPublished - 2004

Keywords

  • gamma rays : observations
  • Galaxy : center
  • black hole physics
  • X-rays : binaries
  • Galaxy : nucleus
  • stars : neutron

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