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http://hdl.handle.net/20.500.12386/26503
Campo DC | Valore | Lingua |
---|---|---|
dc.contributor.author | Gabriele A. Matzeu | en_US |
dc.contributor.author | James N. Reeves | en_US |
dc.contributor.author | NARDINI, EMANUELE | en_US |
dc.contributor.author | BRAITO, Valentina | en_US |
dc.contributor.author | Michele T Costa | en_US |
dc.contributor.author | Tombesi, Francesco | en_US |
dc.contributor.author | Jason Gofford | en_US |
dc.date.accessioned | 2020-07-20T07:25:45Z | - |
dc.date.available | 2020-07-20T07:25:45Z | - |
dc.date.issued | 2016 | en_US |
dc.identifier.issn | 0035-8711 | en_US |
dc.identifier.uri | http://hdl.handle.net/20.500.12386/26503 | - |
dc.description.abstract | We present an analysis of the 2013 Suzaku campaign on the nearby luminous quasar PDS 456, covering a total duration of ~1 Ms and a net exposure of 455 ks. During these observations, the X-ray flux was suppressed by a factor of >10 in the soft X-ray band when compared to other epochs. We investigated the broadband continuum by constructing a spectral energy distribution, making use of the optical/UV photometry and hard X-ray spectra from the later XMM-Newton/NuSTAR campaign in 2014. The high energy part of this low flux state cannot be accounted for by self-consistent accretion disc and corona models without attenuation by absorbing gas, which partially covers a substantial fraction of the line of sight towards the X-ray source. Two absorption layers are required, of column density $\log (N_{\rm{H,low}}/{\rm cm^{-2}})=22.3\pm0.1$ and $\log (N_{\rm{H,high}}/{\rm cm^{-2}})=23.2\pm0.1$, with average covering factors of ~80% (with typical 5% variations) and 60% ($\pm$10-15%), respectively. In these observations PDS 456 displays significant short term X-ray spectral variability, on timescales of ~100 ks, which can be accounted for by variable covering of the absorbing gas. The partial covering absorber prefers an outflow velocity of $v_{\rm pc} = 0.25^{+0.01}_{-0.05}c$ at the >99.9% confidence level over the case where $v_{\rm pc}=0$. This is consistent with the velocity of the highly ionised outflow responsible for the blueshifted iron K absorption profile. We therefore suggest that the partial covering clouds could be the denser, or clumpy part of an inhomogeneous accretion disc wind. Finally we estimate the size-scale of the X-ray source from its variability. The radial extent of the X-ray emitter is found to be of the order ~15-20 $R_{\rm g}$, although the hard X-ray (>2 keV) emission may originate from a more compact or patchy corona of hot electrons, which is ~6-8 $R_{\rm g}$ in size. | en_US |
dc.language.iso | eng | en_US |
dc.title | Short term X-ray spectral variability of the quasar PDS 456 observed in a low flux state | en_US |
dc.type | Article | - |
dc.identifier.doi | 10.1093/mnras/stw354 | en_US |
dc.identifier.scopus | 2-s2.0-84963930807 | en_US |
dc.identifier.isi | 000374569600015 | en_US |
dc.identifier.url | https://academic.oup.com/mnras/article/458/2/1311/2589044 | en_US |
dc.relation.medium | STAMPA | en_US |
dc.relation.volume | 458 | en_US |
dc.relation.issue | 2 | en_US |
dc.relation.firstpage | 1311 | en_US |
dc.relation.lastpage | 1329 | en_US |
dc.type.referee | REF_1 | en_US |
dc.description.numberofauthors | 7 | en_US |
dc.description.international | sì | en_US |
dc.relation.scientificsector | FIS/05 - ASTRONOMIA E ASTROFISICA | en_US |
dc.relation.journal | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | en_US |
dc.type.miur | 262 Articolo in rivista | en_US |
dc.identifier.adsbibcode | 2016MNRAS.458.1311M | 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::PE9_6 Stars and stellar systems | 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 | O.A. Arcetri | - |
crisitem.author.dept | O.A. Brera | - |
crisitem.author.dept | O.A. Roma | - |
crisitem.author.orcid | 0000-0001-9226-8992 | - |
crisitem.author.orcid | 0000-0002-2629-4989 | - |
crisitem.author.orcid | 0000-0002-6562-8654 | - |
crisitem.journal.journalissn | 0035-8711 | - |
crisitem.journal.ance | E112946 | - |
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