The 2-8 keV X-ray number counts determined from Chandra blank field observations

L. L. Cowie; G. P. Garmire; M. W. Bautz; A. J. Barger; W. N. Brandt; A. E. Hornschemeier

doi:10.1086/339545

The 2-8 keV X-ray number counts determined from Chandra blank field observations

L. L. Cowie, G. P. Garmire, M. W. Bautz, A. J. Barger, W. N. Brandt, A. E. Hornschemeier

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Abstract

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 × 10 ^-16 to 10^-13 ergs cm^-2 s^-1. Over this flux range, the contribution to the X-ray background is 1.1 × 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 × 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 × 10^-11 ergs cm ^-2 s^-1 deg^-2 could still be present in an unresolved component.

Original language	English (US)
Pages (from-to)	L5-L8
Journal	Astrophysical Journal
Volume	566
Issue number	1 II
DOIs	https://doi.org/10.1086/339545
State	Published - Feb 10 2002

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.1086/339545

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@article{acf31f8e27b643ad93f8bb4328a63e70,

title = "The 2-8 keV X-ray number counts determined from Chandra blank field observations",

abstract = "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 × 10 -16 to 10-13 ergs cm-2 s-1. Over this flux range, the contribution to the X-ray background is 1.1 × 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 × 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 × 10-11 ergs cm -2 s-1 deg-2 could still be present in an unresolved component.",

author = "Cowie, {L. L.} and Garmire, {G. P.} and Bautz, {M. W.} and Barger, {A. J.} and Brandt, {W. N.} and Hornschemeier, {A. E.}",

note = "Funding Information: We thank Sergio Campana for supplying the data on the CDF-S. Support came from NASA grant DF1-2001X (L. L. C.), NSF grant AST 00-84816 (L. L. C.), NASA grant NAS 8-38252 (G. P. G., PI), University of Wisconsin Research Committee funds granted by the Wisconsin Alumni Research Foundation (A. J. B.), Hubble Fellowship grant HF-01117.01-A (A. J. B.), NSF grant AST 00-84847 (A. J. B.), NSF CAREER award AST 99-83783 (W. N. B.), NASA GSRP grant NGT 5-50247 (A. E. H.), and the Pennsylvania Space Grant Consortium (A. E. H.).",

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T1 - The 2-8 keV X-ray number counts determined from Chandra blank field observations

AU - Cowie, L. L.

AU - Garmire, G. P.

AU - Bautz, M. W.

AU - Barger, A. J.

AU - Brandt, W. N.

AU - Hornschemeier, A. E.

N1 - Funding Information: We thank Sergio Campana for supplying the data on the CDF-S. Support came from NASA grant DF1-2001X (L. L. C.), NSF grant AST 00-84816 (L. L. C.), NASA grant NAS 8-38252 (G. P. G., PI), University of Wisconsin Research Committee funds granted by the Wisconsin Alumni Research Foundation (A. J. B.), Hubble Fellowship grant HF-01117.01-A (A. J. B.), NSF grant AST 00-84847 (A. J. B.), NSF CAREER award AST 99-83783 (W. N. B.), NASA GSRP grant NGT 5-50247 (A. E. H.), and the Pennsylvania Space Grant Consortium (A. E. H.).

PY - 2002/2/10

Y1 - 2002/2/10

N2 - 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 × 10 -16 to 10-13 ergs cm-2 s-1. Over this flux range, the contribution to the X-ray background is 1.1 × 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 × 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 × 10-11 ergs cm -2 s-1 deg-2 could still be present in an unresolved component.

AB - 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 × 10 -16 to 10-13 ergs cm-2 s-1. Over this flux range, the contribution to the X-ray background is 1.1 × 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 × 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 × 10-11 ergs cm -2 s-1 deg-2 could still be present in an unresolved component.

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DO - 10.1086/339545

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SN - 0004-637X

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SP - L5-L8

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1 II

ER -

The 2-8 keV X-ray number counts determined from Chandra blank field observations

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