期刊
ASTROPHYSICAL JOURNAL
卷 566, 期 1, 页码 L5-L8出版社
IOP PUBLISHING LTD
DOI: 10.1086/339545
关键词
cosmology : observations; galaxies : active; galaxies : distances and redshifts; galaxies : evolution; galaxies : formation; galaxies : starburst
We present the 2-8 keV number counts from the 1 Ms Chandra observation of the Chandra Deep Field-North. We combine these with the number counts from a 78 ks exposure of the Hawaii Survey field SSA22 and with the number counts obtained in independent analyses of the Chandra Deep Field-South and the Hawaii Survey field SSA13 to determine the number counts from 2 x 10(-16) to 10(-13) ergs cm(-2) s(-1). Over this flux range, the contribution to the X-ray background is 1.1 x 10(-11) ergs cm(-2) s(-1) deg(-2). When the contributions above 10(-13) ergs cm(-2) s(-1) from BeppoSAX or ASCA observations are included, the total rises to 1.4 x 10(-11) ergs cm(-2) s(-1) deg(-2). However, there appears to be substantial field-to-field variation in the counts in excess of the statistical uncertainties. When the statistical and flux-calibration uncertainties (in both the background and source measurements) are taken into account, as much as 0.5 x 10(-11) ergs cm(-2) s(-1) deg(-2) could still be present in an unresolved component.
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