Please use this identifier to cite or link to this item:
http://hdl.handle.net/20.500.12386/27087
DC Field | Value | Language |
---|---|---|
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 | - |
Appears in Collections: | 1.01 Articoli in rivista |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
1704.08693.pdf | preprint | 1.91 MB | Adobe PDF | View/Open |
aa30484-17.pdf | Pdf editoriale | 3.3 MB | Adobe PDF | View/Open |
Page view(s)
62
checked on Apr 19, 2024
Download(s)
28
checked on Apr 19, 2024
Google ScholarTM
Check
Altmetric
Altmetric
Items in DSpace are published in Open Access, unless otherwise indicated.