Please use this identifier to cite or link to this item:
http://hdl.handle.net/20.500.12386/26294
DC Field | Value | Language |
---|---|---|
dc.contributor.author | MARCHESI, STEFANO | en_US |
dc.contributor.author | Civano, F. | en_US |
dc.contributor.author | Salvato, M. | en_US |
dc.contributor.author | Shankar, F. | en_US |
dc.contributor.author | COMASTRI, Andrea | en_US |
dc.contributor.author | Elvis, M. | en_US |
dc.contributor.author | LANZUISI, Giorgio | en_US |
dc.contributor.author | Trakhtenbrot, B. | en_US |
dc.contributor.author | Vignali, C. | en_US |
dc.contributor.author | Zamorani, G. | en_US |
dc.contributor.author | Allevato, V. | en_US |
dc.contributor.author | Brusa, M. | en_US |
dc.contributor.author | Fiore, F. | en_US |
dc.contributor.author | GILLI, Roberto | en_US |
dc.contributor.author | Griffiths, R. | en_US |
dc.contributor.author | Hasinger, G. | en_US |
dc.contributor.author | Miyaji, T. | en_US |
dc.contributor.author | Schawinski, K. | en_US |
dc.contributor.author | Treister, E. | en_US |
dc.contributor.author | Urry, C. M. | en_US |
dc.date.accessioned | 2020-07-02T15:16:07Z | - |
dc.date.available | 2020-07-02T15:16:07Z | - |
dc.date.issued | 2016 | en_US |
dc.identifier.issn | 0004-637X | en_US |
dc.identifier.uri | http://hdl.handle.net/20.500.12386/26294 | - |
dc.description.abstract | We present the largest high-redshift (3 < z < 6.85) sample of X-ray-selected active galactic nuclei (AGNs) on a contiguous field, using sources detected in the Chandra COSMOS-Legacy survey. The sample contains 174 sources, 87 with spectroscopic redshift and the other 87 with photometric redshift (z <SUB>phot</SUB>). In this work, we treat z <SUB>phot</SUB> as a probability-weighted sum of contributions, adding to our sample the contribution of sources with z <SUB>phot</SUB> < 3 but z <SUB>phot</SUB> probability distribution >0 at z > 3. We compute the number counts in the observed 0.5-2 keV band, finding a decline in the number of sources at z > 3 and constraining phenomenological models of the X-ray background. We compute the AGN space density at z > 3 in two different luminosity bins. At higher luminosities (logL(2-10 keV) > 44.1 erg s<SUP>-1</SUP>), the space density declines exponentially, dropping by a factor of ∼20 from z ∼ 3 to z ∼ 6. The observed decline is ∼80% steeper at lower luminosities (43.55 erg s<SUP>-1</SUP> < logL(2-10 keV) < 44.1 erg s<SUP>-1</SUP>) from z ∼ 3 to z ∼ 4.5. We study the space density evolution dividing our sample into optically classified Type 1 and Type 2 AGNs. At logL(2-10 keV) > 44.1 erg s<SUP>-1</SUP>, unobscured and obscured objects may have different evolution with redshift, with the obscured component being three times higher at z ∼ 5. Finally, we compare our space density with predictions of quasar activation merger models, whose calibration is based on optically luminous AGNs. These models significantly overpredict the number of expected AGNs at logL (2-10 keV) > 44.1 erg s<SUP>-1</SUP> with respect to our data. | en_US |
dc.language.iso | eng | en_US |
dc.title | The Chandra COSMOS-Legacy Survey: The z>3 Sample | en_US |
dc.type | Article | - |
dc.identifier.doi | 10.3847/0004-637X/827/2/150 | en_US |
dc.identifier.scopus | 2-s2.0-84984669440 | en_US |
dc.identifier.isi | 000384001600062 | en_US |
dc.identifier.url | https://iopscience.iop.org/article/10.3847/0004-637X/827/2/150 | en_US |
dc.relation.medium | STAMPA | en_US |
dc.relation.volume | 827 | en_US |
dc.relation.issue | 2 | en_US |
dc.relation.firstpage | 150 | en_US |
dc.type.referee | REF_1 | en_US |
dc.description.numberofauthors | 20 | en_US |
dc.description.international | sì | en_US |
dc.contributor.country | ITA | en_US |
dc.contributor.country | USA | en_US |
dc.contributor.country | GBR | en_US |
dc.contributor.country | DEU | en_US |
dc.contributor.country | CHL | en_US |
dc.contributor.country | FIN | en_US |
dc.contributor.country | MEX | en_US |
dc.contributor.country | CHE | en_US |
dc.relation.scientificsector | FIS/05 - ASTRONOMIA E ASTROFISICA | en_US |
dc.relation.journal | THE ASTROPHYSICAL JOURNAL | en_US |
dc.type.miur | 262 Articolo in rivista | - |
dc.identifier.adsbibcode | 2016ApJ...827..150M | 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 | OAS Bologna | - |
crisitem.author.dept | OAS Bologna | - |
crisitem.author.dept | OAS Bologna | - |
crisitem.author.orcid | 0000-0001-5544-0749 | - |
crisitem.author.orcid | 0000-0003-3451-9970 | - |
crisitem.author.orcid | 0000-0001-9094-0984 | - |
crisitem.author.orcid | 0000-0001-8121-6177 | - |
crisitem.journal.journalissn | 0004-637X | - |
crisitem.journal.ance | E016252 | - |
Appears in Collections: | 1.01 Articoli in rivista |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
Marchesi_2016_ApJ_827_150.pdf | Pdf editoriale | 2.15 MB | Adobe PDF | View/Open |
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