Abstract
We present data analysis and X-ray source counts for the first season of XMM-Newton observations in the COSMOS field. The survey covers ∼2 deg 2 within the region of sky bounded by 09 h57 m30 s < R.A. < 10 h03 m30 s, 01°27′30″ < decl. < 02°57′ 30″ with a total net integration time of 504 ks. A maximum likelihood source detection was performed in the 0.5-2, 2-4.5, and 4.5-10 keV energy bands, and 1390 pointlike sources were detected in at least one band. Detailed Monte Carlo simulations were performed to fully test the source-detection method and to derive the sky coverage to be used in the computation of the log N-log S relations. These relations were then derived in the 0.5-2, 2-10, and 5-10 keV energy bands, down to flux limits of 7.2 × 10 -16 ergs cm -2 s -1,4.0 × 10 -15 ergs cm -2 s -1, and 9.7 × 10 -15 ergs cm -2 s -1, respectively. Thanks to the large number of sources detected in the COSMOS survey, the log N-log S curves are tightly constrained over a range of fluxes which were poorly covered by previous surveys, especially in the 2-10 and 5-10 keV bands. The 0.5-2 and 2-10 keV differential log N-log S relations were fitted with a broken power-law model which revealed a Euclidean slope at the bright end and a flatter slope (α ∼ 1.5) at faint fluxes. In the 5-10 keV energy band a single power law provides an acceptable fit to the observed source counts with a slope α ∼ 2.4. A comparison with the results of previous surveys shows good agreement in all the energy bands under investigation in the overlapping flux range. We also notice a remarkable agreement between our log N-log S relations and the most recent model of the X-ray background.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 341-352 |
| Number of pages | 12 |
| Journal | Astrophysical Journal, Supplement Series |
| Volume | 172 |
| Issue number | 1 |
| DOIs | |
| State | Published - Oct 22 2007 |
| Externally published | Yes |
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Keywords
- Cosmology: observations
- Dark matter
- Galaxies: evolution
- Galaxies: formation
- Large-scale structure of universe
- Surveys
ASJC Scopus subject areas
- Space and Planetary Science
Cite this
The XMM-Newton wide-field survey in the COSMOS field. II. X-ray data and the log N-log S relations. / Cappelluti, Nico; Hasinger, G.; Brusa, M.; Comastri, A.; Zamorani, G.; Böhringer, H.; Brunner, H.; Civano, F.; Finoguenov, A.; Fiore, F.; Gilli, R.; Griffiths, R. E.; Mainieri, V.; Matute, I.; Miyaji, T.; Silverman, J.
In: Astrophysical Journal, Supplement Series, Vol. 172, No. 1, 22.10.2007, p. 341-352.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The XMM-Newton wide-field survey in the COSMOS field. II. X-ray data and the log N-log S relations
AU - Cappelluti, Nico
AU - Hasinger, G.
AU - Brusa, M.
AU - Comastri, A.
AU - Zamorani, G.
AU - Böhringer, H.
AU - Brunner, H.
AU - Civano, F.
AU - Finoguenov, A.
AU - Fiore, F.
AU - Gilli, R.
AU - Griffiths, R. E.
AU - Mainieri, V.
AU - Matute, I.
AU - Miyaji, T.
AU - Silverman, J.
PY - 2007/10/22
Y1 - 2007/10/22
N2 - We present data analysis and X-ray source counts for the first season of XMM-Newton observations in the COSMOS field. The survey covers ∼2 deg 2 within the region of sky bounded by 09 h57 m30 s < R.A. < 10 h03 m30 s, 01°27′30″ < decl. < 02°57′ 30″ with a total net integration time of 504 ks. A maximum likelihood source detection was performed in the 0.5-2, 2-4.5, and 4.5-10 keV energy bands, and 1390 pointlike sources were detected in at least one band. Detailed Monte Carlo simulations were performed to fully test the source-detection method and to derive the sky coverage to be used in the computation of the log N-log S relations. These relations were then derived in the 0.5-2, 2-10, and 5-10 keV energy bands, down to flux limits of 7.2 × 10 -16 ergs cm -2 s -1,4.0 × 10 -15 ergs cm -2 s -1, and 9.7 × 10 -15 ergs cm -2 s -1, respectively. Thanks to the large number of sources detected in the COSMOS survey, the log N-log S curves are tightly constrained over a range of fluxes which were poorly covered by previous surveys, especially in the 2-10 and 5-10 keV bands. The 0.5-2 and 2-10 keV differential log N-log S relations were fitted with a broken power-law model which revealed a Euclidean slope at the bright end and a flatter slope (α ∼ 1.5) at faint fluxes. In the 5-10 keV energy band a single power law provides an acceptable fit to the observed source counts with a slope α ∼ 2.4. A comparison with the results of previous surveys shows good agreement in all the energy bands under investigation in the overlapping flux range. We also notice a remarkable agreement between our log N-log S relations and the most recent model of the X-ray background.
AB - We present data analysis and X-ray source counts for the first season of XMM-Newton observations in the COSMOS field. The survey covers ∼2 deg 2 within the region of sky bounded by 09 h57 m30 s < R.A. < 10 h03 m30 s, 01°27′30″ < decl. < 02°57′ 30″ with a total net integration time of 504 ks. A maximum likelihood source detection was performed in the 0.5-2, 2-4.5, and 4.5-10 keV energy bands, and 1390 pointlike sources were detected in at least one band. Detailed Monte Carlo simulations were performed to fully test the source-detection method and to derive the sky coverage to be used in the computation of the log N-log S relations. These relations were then derived in the 0.5-2, 2-10, and 5-10 keV energy bands, down to flux limits of 7.2 × 10 -16 ergs cm -2 s -1,4.0 × 10 -15 ergs cm -2 s -1, and 9.7 × 10 -15 ergs cm -2 s -1, respectively. Thanks to the large number of sources detected in the COSMOS survey, the log N-log S curves are tightly constrained over a range of fluxes which were poorly covered by previous surveys, especially in the 2-10 and 5-10 keV bands. The 0.5-2 and 2-10 keV differential log N-log S relations were fitted with a broken power-law model which revealed a Euclidean slope at the bright end and a flatter slope (α ∼ 1.5) at faint fluxes. In the 5-10 keV energy band a single power law provides an acceptable fit to the observed source counts with a slope α ∼ 2.4. A comparison with the results of previous surveys shows good agreement in all the energy bands under investigation in the overlapping flux range. We also notice a remarkable agreement between our log N-log S relations and the most recent model of the X-ray background.
KW - Cosmology: observations
KW - Dark matter
KW - Galaxies: evolution
KW - Galaxies: formation
KW - Large-scale structure of universe
KW - Surveys
UR - http://www.scopus.com/inward/record.url?scp=35348816013&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=35348816013&partnerID=8YFLogxK
U2 - 10.1086/516586
DO - 10.1086/516586
M3 - Article
AN - SCOPUS:35348816013
VL - 172
SP - 341
EP - 352
JO - Astrophysical Journal, Supplement Series
JF - Astrophysical Journal, Supplement Series
SN - 0067-0049
IS - 1
ER -