Utilizza questo identificativo per citare o creare un link a questo documento:
http://hdl.handle.net/20.500.12386/27087
Campo DC | Valore | Lingua |
---|---|---|
dc.contributor.author | Nanni, R. | en_US |
dc.contributor.author | Vignali, C. | en_US |
dc.contributor.author | GILLI, Roberto | en_US |
dc.contributor.author | MORETTI, Alberto | en_US |
dc.contributor.author | Brandt, W. N. | en_US |
dc.date.accessioned | 2020-09-03T10:40:46Z | - |
dc.date.available | 2020-09-03T10:40:46Z | - |
dc.date.issued | 2017 | en_US |
dc.identifier.issn | 0004-6361 | en_US |
dc.identifier.uri | http://hdl.handle.net/20.500.12386/27087 | - |
dc.description.abstract | We present a systematic analysis of X-ray archival data of all the 29 quasars (QSOs) at z> 5.5 observed so far with Chandra, XMM-Newton and Swift-XRT, including the most-distant quasar ever discovered, ULAS J1120+0641 (z = 7.08). This study allows us to place constraints on the mean spectral properties of the primordial population of luminous Type 1 (unobscured) quasars. Eighteen quasars are detected in the X-ray band, and we provide spectral-fitting results for their X-ray properties, while for the others we provide upper limits to their soft (0.5-2.0 keV) X-ray flux. We measured the power-law photon index and derived an upper limit to the column density for the five quasars (J1306+0356, J0100+2802, J1030+0524, J1148+5251, J1120+0641) with the best spectra (>30 net counts in the 0.5-7.0 keV energy range) and find that they are consistent with values from the literature and lower-redshift quasars. By stacking the spectra of ten quasars detected by Chandra in the redshift range 5.7 ≤ z ≤ 6.1 we find a mean X-ray power-law photon index of Γ = 1.92<SUB>-0.27</SUB><SUP>+0.28</SUP> and a neutral intrinsic absorption column density of N<SUB>H</SUB> ≤ 10<SUP>23</SUP> cm<SUP>-2</SUP>. These results suggest that the X-ray spectral properties of luminous quasars have not evolved up to z ≈ 6. We also derived the optical-X-ray spectral slopes (α<SUB>ox</SUB>) of our sample and combined them with those of previous works, confirming that α<SUB>ox</SUB> strongly correlates with UV monochromatic luminosity at 2500 Å. These results strengthen the non-evolutionary scenario for the spectral properties of luminous active galactic nuclei (AGN). | en_US |
dc.language.iso | eng | en_US |
dc.title | The X-ray properties of z 6 luminous quasars | en_US |
dc.type | Article | - |
dc.identifier.doi | 10.1051/0004-6361/201730484 | en_US |
dc.identifier.scopus | 2-s2.0-85025461065 | en_US |
dc.identifier.isi | 000406619100098 | en_US |
dc.identifier.url | https://arxiv.org/abs/1704.08693 | en_US |
dc.identifier.url | https://www.aanda.org/articles/aa/abs/2017/07/aa30484-17/aa30484-17.html | en_US |
dc.relation.medium | STAMPA | en_US |
dc.relation.volume | 603 | en_US |
dc.relation.firstpage | A128 | en_US |
dc.type.referee | REF_1 | en_US |
dc.description.numberofauthors | 5 | en_US |
dc.description.international | sì | en_US |
dc.contributor.country | ITA | en_US |
dc.relation.scientificsector | FIS/05 - ASTRONOMIA E ASTROFISICA | en_US |
dc.relation.journal | ASTRONOMY & ASTROPHYSICS | en_US |
dc.type.miur | 262 Articolo in rivista | - |
dc.identifier.adsbibcode | 2017A&A...603A.128N | en_US |
dc.relation.ercsector | ERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation | en_US |
dc.description.apc | no | en_US |
dc.description.oa | 1 – prodotto con file in versione Open Access (allegare il file al passo 5-Carica) | en_US |
item.openairecristype | http://purl.org/coar/resource_type/c_18cf | - |
item.openairetype | Article | - |
item.languageiso639-1 | en | - |
item.cerifentitytype | Publications | - |
item.grantfulltext | open | - |
item.fulltext | With Fulltext | - |
crisitem.author.dept | OAS Bologna | - |
crisitem.author.dept | O.A. Brera | - |
crisitem.author.orcid | 0000-0001-8121-6177 | - |
crisitem.author.orcid | 0000-0002-9770-0315 | - |
crisitem.journal.journalissn | 0004-6361 | - |
crisitem.journal.ance | E016240 | - |
È visualizzato nelle collezioni: | 1.01 Articoli in rivista |
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File | Descrizione | Dimensioni | Formato | |
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1704.08693.pdf | preprint | 1.91 MB | Adobe PDF | Visualizza/apri |
aa30484-17.pdf | Pdf editoriale | 3.3 MB | Adobe PDF | Visualizza/apri |
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