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http://hdl.handle.net/10261/170243
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dc.contributor.author | Mateos, Silvia | - |
dc.contributor.author | Barcons, Xavier | - |
dc.contributor.author | Carrera, Francisco J. | - |
dc.contributor.author | Ceballos, María Teresa | - |
dc.contributor.author | Hasinger, Günther | - |
dc.contributor.author | Lehmann, I. | - |
dc.contributor.author | Fabian, Andrew C. | - |
dc.contributor.author | Streblyanska, Alina | - |
dc.date.accessioned | 2018-09-26T12:26:48Z | - |
dc.date.available | 2018-09-26T12:26:48Z | - |
dc.date.issued | 2005 | - |
dc.identifier | doi: 10.1051/0004-6361:20052881 | - |
dc.identifier | issn: 0004-6361 | - |
dc.identifier | e-issn: 1432-0746 | - |
dc.identifier.citation | Astronomy and Astrophysics 444(1): 79-99 (2005) | - |
dc.identifier.uri | http://hdl.handle.net/10261/170243 | - |
dc.description.abstract | This paper presents the results of a detailed X-ray spectral analysis of a sample of 123 X-ray sources detected with XMM-Newton in the Lockman Hole field. This is the deepest observation carried out with XMM-Newton with more that 600 ks of good EPIC-pn data. We have spectra with good signal to noise (>500 source counts) for all objects down to 0.2-12 keV fluxes of ∼ 5 × 10-15 erg cm-2 s-1 (flux limit of ∼6 × 10-16 erg cm-2 s-1 in the 0.5-2 and 2-10 keV bands). At the time of the analysis, we had optical spectroscopic identifications for 60% of the sources, 46 being optical type-1 AGN and 28 optical type-2 AGN. Using a single power law model our sources' average spectral slope hardens at faint 0.5-2 keV fluxes but not at faint 2-10 keV fluxes. We have been able to explain this effect in terms of an increase in X-ray absorption at faint fluxes. We did not find in our data any evidence for the existence of a population of faint intrinsically harder sources. The average spectral slope of our sources is ∼1.9, with an intrinsic dispersion of ∼0.28. We detected X-ray absorption (F-test significance ≥95%) in 37% of the sources, ∼10% in type-1 AGN (rest-frame NH ∼ 1.6 × 1021 - 1.2 × 1022 cm-2) and ∼77% (rest-frame NH ∼ 1.5 × 1021 - 4 × 10 23 cm-2) in type-2 AGN. Using X-ray fluxes corrected for absorption, the fraction of absorbed objects and the absorbing column density distribution did not vary with X-ray flux. Our type-1 and type-2 AGN do not appear to have different continuum shapes, but the distribution of intrinsic (rest-frame) absorbing column densities is different among both classes. A significant fraction of our type-2 AGN (5 out of 28) were found to display no substantial absorption (NH < 1021 cm-2). We discuss possible interpretations to this in terms of Compton-thick AGN and intrinsic Broad Line Region properties. An emission line compatible with Fe Ka was detected in 8 sources (1 type-1 AGN, 5 type-2 AGN and 2 unidentified) with rest frame equivalent widths 120-1000 eV. However weak broad components can be easily missed in other sources by the relatively noisy data. The AGN continuum or intrinsic absorption did not depend on X-ray luminosity and/or redshift. Soft excess emission was detected in 18 objects, but only in 9 (including 4 type-1 AGN and 4 type-2 AGN) could we fit this spectral component with a black body model. The measured 0.5-2 keV luminosities of the fitted black body were not significantly different in type-1 and type-2 AGN, although the temperatures of the black body were slightly higher in type-2 AGN (〈kT〉) = 0.26 ± 0.08) than in type-1 AGN (〈kT〉 = 0.09 ± 0.01). For 9 sources (including 1 type-1 AGN and 3 type-2 AGN) a scattering model provided a better fit of the soft excess emission. We found that the integrated contribution from our sources to the X-ray background in the 2-7 keV band is softer (Γ = 1.5-1.6) than the background itself, implying that fainter sources need to be more absorbed. | - |
dc.description.sponsorship | S.M. acknowledges support from a Universidad de Cantabria fellowship. X.B., F.J.C. and M.T.C. acknowledge financial support from the Spanish Ministerio de Educación y Ciencia, under project ESP2003-00812. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. | - |
dc.publisher | EDP Sciences | - |
dc.relation.isversionof | Publisher's version | - |
dc.rights | openAccess | - |
dc.subject | X-rays: diffuse background | - |
dc.subject | Surveys | - |
dc.subject | Galaxies: active | - |
dc.subject | X-ray general | - |
dc.title | XMM-Newton observations of the Lockman Hole IV: spectra of the brightest AGN | - |
dc.type | artículo | - |
dc.identifier.doi | 10.1051/0004-6361:20052881 | - |
dc.relation.publisherversion | https://doi.org/10.1051/0004-6361:20052881 | - |
dc.date.updated | 2018-09-26T12:26:48Z | - |
dc.description.version | Peer Reviewed | - |
dc.language.rfc3066 | eng | - |
dc.contributor.funder | Universidad de Cantabria | - |
dc.contributor.funder | W. M. Keck Foundation | - |
dc.contributor.funder | Ministerio de Educación y Ciencia (España) | - |
dc.relation.csic | Sí | - |
dc.identifier.funder | http://dx.doi.org/10.13039/501100006365 | es_ES |
dc.identifier.funder | http://dx.doi.org/10.13039/100000888 | es_ES |
dc.type.coar | http://purl.org/coar/resource_type/c_6501 | es_ES |
item.cerifentitytype | Publications | - |
item.openairecristype | http://purl.org/coar/resource_type/c_18cf | - |
item.grantfulltext | open | - |
item.openairetype | artículo | - |
item.fulltext | With Fulltext | - |
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