2006A&A...452..169R -
Astronomy and Astrophysics, volume 452, 169-178 (2006/6-2)
Origin of the Galactic ridge X-ray emission.
REVNIVTSEV M., SAZONOV S., GILFANOV M., CHURAZOV E. and SUNYAEV R.
Abstract (from CDS):
We analyze a map of the Galactic ridge X-ray emission (GRXE) constructed in the 3-20keV energy band from RXTE/PCA scan and slew observations. We show that the GRXE intensity follows the Galactic near-infrared surface brightness closely and thus traces the Galactic stellar mass distribution. The GRXE consists of two spatial components that can be identified with the bulge/bar and the disk of the Galaxy. The parameters of these components determined from X-ray data are compatible with those derived from near-infrared data. The inferred ratio of X-ray to near-infrared surface brightness I
3–20keV(10
–11erg/s/cm2/deg2)/I
3.5µm(MJy/sr)=0.26±0.05, and the ratio of X-ray to near-infrared luminosity L
3–20keV/L
3–4µm=(4.1±0.3)x10
–5. The corresponding ratio of the 3-20keV luminosity to the stellar mass is L
x/M=(3.5±0.5)x10
27erg/s/M
☉, which agrees within the uncertainties with the cumulative emissivity per unit stellar mass of point X-ray sources in the Solar neighborhood, determined in an accompanying paper (Sazonov et al.,
2006A&A...450..117S). This suggests that the bulk of the GRXE is composed of weak X-ray sources, mostly cataclysmic variables and coronally active binaries. The fractional contributions of these classes of sources to the total X-ray emissivity determined from the Solar neighborhood data can also explain the GRXE energy spectrum. Based on the luminosity function of local X-ray sources we predict that, in order to resolve 90% of the GRXE into discrete sources, a sensitivity limit of ∼10
–16erg/s/cm2 (2-10keV) will need to be reached in future observations.
Abstract Copyright:
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Journal keyword(s):
stars: binaries: general - Galaxy: bulge - Galaxy: disk - X-rays: general - X-rays: stars
Simbad objects:
11
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