Astronomy and Astrophysics – Astronomy
Scientific paper
Mar 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997mnras.285..449c&link_type=abstract
Monthly Notices of the Royal Astronomical Society, Volume 285, Issue 3, pp. 449-471.
Astronomy and Astrophysics
Astronomy
89
Cosmology: Observations, Diffuse Radiation, Large-Scale Structure Of Universe, X-Rays: General
Scientific paper
The X-ray background from 0.1 to 7 keV has been studied using data of high spectral and spatial resolution from the ASCA Solid-state Imaging Spectrometers and ROSAT Position Sensitive Proportional Counter. Analysing both the diffuse background radiation and resolved sources, we have carried out a series of joint spectral fits of the ASCA and ROSAT data. As found previously with ASCA data alone, the spectrum of the X-ray background can be fitted well by a single power law from 1 to 7 keV; to account for the Galactic emission below 1 keV, a model with a power law plus two thermal components fits well to the measurements of ASCA and ROSAT from 0.1 to 7 keV. Overall, the photon index of the power-law model ranges from 1.4 to 1.5, and no obvious excess is found between 1 and 3 keV as predicted from some previous observations. Below 1 keV, the models become more complicated and involve a mixture of extragalactic and Galactic sources. As some of the extragalactic contributions should be from point sources, we have examined the ASCA and ROSAT spectra of resolved sources individually: a stellar source having a well-fitted thermal spectrum and two AGN having a much steeper power-law spectrum (with a photon index of about 3); the accumulated spectrum of other non-stellar sources resolved by ROSAT is also steeper than the average AGN spectrum. Fitting the X-ray background spectrum observed by ASCA and the accumulated point source spectrum by ROSAT together by varying the contribution from steep-spectrum sources, such as quasars, to the background, we find that the steep-spectrum sources contribute less than 30 per cent in the 0.5-2 keV band and drop to below 10 per cent over 2-10 keV. This fraction is provided by sources brighter than a few times 10^-15 erg cm^-2 s^-1 (in the 0.5-2 keV band). Constrained by our spectral fitting results, the major contributor of the X-ray background must be a single population with similar flat spectra.
Chen Lie-Wen
Fabian Andrea C.
Gendreau Keith Charles
No associations
LandOfFree
ASCA and ROSAT observations of the QSF3 field: the X-ray background in the 0.1-7 keV band does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with ASCA and ROSAT observations of the QSF3 field: the X-ray background in the 0.1-7 keV band, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and ASCA and ROSAT observations of the QSF3 field: the X-ray background in the 0.1-7 keV band will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-874666