Abstract
We present a detailed spectral analysis of pointlike X-ray sources in the XMM-Newton COSMOS field. Our sample of 135 sources only includes those that have more than 100 net counts in the 0.3-10 keV energy band and have been identified through optical spectroscopy. The majority of the sources are well described by a simple power-law model with either no absorption (76%) or a significant intrinsic, absorbing column (20%). The remaining ∼4% of the sources require a more complex modeling by incorporating additional components to the power law. For sources with more than 180 net counts (bright sample), we allowed both the photon spectral index Γ and the equivalent hydrogen column N H to be free parameters. For fainter sources, we fix Γ to the average value and allow N H to vary. The mean spectral index of the 82 sources in the bright sample is (Γ) = 2.06 ± 0.08, with an intrinsic dispersion of ∼0.24. Each of these sources has fractional errors on the value of T below 20%. As expected, the distribution of intrinsic absorbing column densities is markedly different between AGNs with or without broad optical emission lines. We find within our sample four type 2 QSO candidates (L X > 10 44 ergs s -1, N H > 10 22 cm -2), with a spectral energy distribution well reproduced by a composite Seyfert 2 spectrum, that demonstrates the strength of the wide-field COSMOS XMM-Newton survey to detect these rare and underrepresented sources. In addition, we have identified a Compton-thick (N H > 1.5 × 10 24 cm -2) AGN at z = 0.1248. Its X-ray spectrum is well fitted by a pure reflection model and a significant Fe Kα line at rest-frame energy of 6.4 keV.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 368-382 |
| Number of pages | 15 |
| Journal | Astrophysical Journal, Supplement Series |
| Volume | 172 |
| Issue number | 1 |
| DOIs | |
| State | Published - Oct 22 2007 |
| Externally published | Yes |
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Keywords
- Galaxies: active
- Surveys
- X-rays: diffuse background
- X-rays: galaxies
- X-rays: general
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
Cite this
The XMM-Newton wide-field survey in the COSMOS field. IV. X-ray spectral properties of active galactic nuclei. / Mainieri, V.; Hasinger, G.; Cappelluti, Nico; Brusa, M.; Brunner, H.; Civano, F.; Comastri, A.; Elvis, M.; Finoguenov, A.; Fiore, F.; Gilli, R.; Lehmann, I.; Silverman, J.; Tasca, L.; Vignali, C.; Zamorani, G.; Schinnerer, E.; Impey, C.; Trump, J.; Lilly, S.; Maier, C.; Griffiths, R. E.; Miyaji, T.; Capak, P.; Koekemoer, A.; Scoville, N.; Shopbell, P.; Taniguchi, Y.
In: Astrophysical Journal, Supplement Series, Vol. 172, No. 1, 22.10.2007, p. 368-382.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The XMM-Newton wide-field survey in the COSMOS field. IV. X-ray spectral properties of active galactic nuclei
AU - Mainieri, V.
AU - Hasinger, G.
AU - Cappelluti, Nico
AU - Brusa, M.
AU - Brunner, H.
AU - Civano, F.
AU - Comastri, A.
AU - Elvis, M.
AU - Finoguenov, A.
AU - Fiore, F.
AU - Gilli, R.
AU - Lehmann, I.
AU - Silverman, J.
AU - Tasca, L.
AU - Vignali, C.
AU - Zamorani, G.
AU - Schinnerer, E.
AU - Impey, C.
AU - Trump, J.
AU - Lilly, S.
AU - Maier, C.
AU - Griffiths, R. E.
AU - Miyaji, T.
AU - Capak, P.
AU - Koekemoer, A.
AU - Scoville, N.
AU - Shopbell, P.
AU - Taniguchi, Y.
PY - 2007/10/22
Y1 - 2007/10/22
N2 - We present a detailed spectral analysis of pointlike X-ray sources in the XMM-Newton COSMOS field. Our sample of 135 sources only includes those that have more than 100 net counts in the 0.3-10 keV energy band and have been identified through optical spectroscopy. The majority of the sources are well described by a simple power-law model with either no absorption (76%) or a significant intrinsic, absorbing column (20%). The remaining ∼4% of the sources require a more complex modeling by incorporating additional components to the power law. For sources with more than 180 net counts (bright sample), we allowed both the photon spectral index Γ and the equivalent hydrogen column N H to be free parameters. For fainter sources, we fix Γ to the average value and allow N H to vary. The mean spectral index of the 82 sources in the bright sample is (Γ) = 2.06 ± 0.08, with an intrinsic dispersion of ∼0.24. Each of these sources has fractional errors on the value of T below 20%. As expected, the distribution of intrinsic absorbing column densities is markedly different between AGNs with or without broad optical emission lines. We find within our sample four type 2 QSO candidates (L X > 10 44 ergs s -1, N H > 10 22 cm -2), with a spectral energy distribution well reproduced by a composite Seyfert 2 spectrum, that demonstrates the strength of the wide-field COSMOS XMM-Newton survey to detect these rare and underrepresented sources. In addition, we have identified a Compton-thick (N H > 1.5 × 10 24 cm -2) AGN at z = 0.1248. Its X-ray spectrum is well fitted by a pure reflection model and a significant Fe Kα line at rest-frame energy of 6.4 keV.
AB - We present a detailed spectral analysis of pointlike X-ray sources in the XMM-Newton COSMOS field. Our sample of 135 sources only includes those that have more than 100 net counts in the 0.3-10 keV energy band and have been identified through optical spectroscopy. The majority of the sources are well described by a simple power-law model with either no absorption (76%) or a significant intrinsic, absorbing column (20%). The remaining ∼4% of the sources require a more complex modeling by incorporating additional components to the power law. For sources with more than 180 net counts (bright sample), we allowed both the photon spectral index Γ and the equivalent hydrogen column N H to be free parameters. For fainter sources, we fix Γ to the average value and allow N H to vary. The mean spectral index of the 82 sources in the bright sample is (Γ) = 2.06 ± 0.08, with an intrinsic dispersion of ∼0.24. Each of these sources has fractional errors on the value of T below 20%. As expected, the distribution of intrinsic absorbing column densities is markedly different between AGNs with or without broad optical emission lines. We find within our sample four type 2 QSO candidates (L X > 10 44 ergs s -1, N H > 10 22 cm -2), with a spectral energy distribution well reproduced by a composite Seyfert 2 spectrum, that demonstrates the strength of the wide-field COSMOS XMM-Newton survey to detect these rare and underrepresented sources. In addition, we have identified a Compton-thick (N H > 1.5 × 10 24 cm -2) AGN at z = 0.1248. Its X-ray spectrum is well fitted by a pure reflection model and a significant Fe Kα line at rest-frame energy of 6.4 keV.
KW - Galaxies: active
KW - Surveys
KW - X-rays: diffuse background
KW - X-rays: galaxies
KW - X-rays: general
UR - http://www.scopus.com/inward/record.url?scp=35348883519&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=35348883519&partnerID=8YFLogxK
U2 - 10.1086/516573
DO - 10.1086/516573
M3 - Article
AN - SCOPUS:35348883519
VL - 172
SP - 368
EP - 382
JO - Astrophysical Journal, Supplement Series
JF - Astrophysical Journal, Supplement Series
SN - 0067-0049
IS - 1
ER -