Please use this identifier to cite or link to this item:
http://hdl.handle.net/20.500.12386/31879
DC Field | Value | Language |
---|---|---|
dc.contributor.author | GRAZIAN, Andrea | en_US |
dc.contributor.author | GIALLONGO, Emanuele | en_US |
dc.contributor.author | FIORE, Fabrizio | en_US |
dc.contributor.author | Boutsia, K. | en_US |
dc.contributor.author | Civano, F. | en_US |
dc.contributor.author | CRISTIANI, Stefano | en_US |
dc.contributor.author | CUPANI, Guido | en_US |
dc.contributor.author | Dickinson, M. | en_US |
dc.contributor.author | FONTANOT, Fabio | en_US |
dc.contributor.author | MENCI, Nicola | en_US |
dc.contributor.author | Romano, M. | en_US |
dc.date.accessioned | 2022-03-24T14:41:32Z | - |
dc.date.available | 2022-03-24T14:41:32Z | - |
dc.date.issued | 2020 | en_US |
dc.identifier.issn | 0004-637X | en_US |
dc.identifier.uri | http://hdl.handle.net/20.500.12386/31879 | - |
dc.description.abstract | It is widespread opinion that hydrogen reionization is mainly driven by primeval star-forming galaxies, with high-z active galactic nuclei (AGNs) having a minor role. Recent observations, however, challenge this notion, indicating a number of issues related to a galaxy-driven reionization scenario. We provide here an updated assessment of the space density of relatively faint (M<SUB>1450</SUB> ∼ -22.5) AGNs at z<SUB>spec</SUB> ∼ 5.5 in order to improve the estimate of the photoionization rate contribution from accreting supermassive black holes. Exploiting deep UV rest-frame ground-based spectra collected at the Very Large Telescope on the CANDELS/GOODS-South field and deep Chandra X-ray images in the CANDELS/GOODS-North and EGS areas, we find two relatively bright (M<SUB>1450</SUB> ∼ -22.5) AGNs at z<SUB>spec</SUB> ∼ 5.5. We derive an AGN space density of Φ = 1.29 × 10<SUP>-6</SUP> cMpc<SUP>-3</SUP> at z ∼ 5.5 and M<SUB>1450</SUB> ∼ -22.5 by simply dividing their observed number by the cosmological volume in the range 5.0 < z < 6.1. Our estimate does not consider corrections for incompleteness; therefore, it represents a lower limit, although uncertainties due to cosmic variance can still be significant. This value supports a high space density of AGNs at z > 5, in contrast with previous claims mostly based on standard color selection, possibly affected by significant incompleteness. Our estimate for the AGN photoionization rate at z ∼ 5.5 is in agreement with the observed values at similar redshifts, which are needed to keep the intergalactic medium highly ionized. Upcoming James Webb Space Telescope and giant ground-based telescopes observations will improve the study of high-z AGNs and their contribution to the reionization of the universe. | en_US |
dc.language.iso | eng | en_US |
dc.title | On the AGN Nature of Two UV-bright Sources at zspec ∼ 5.5 in the CANDELS Fields: An Update on the AGN Space Density at M1450 ∼ −22.5 | en_US |
dc.type | Article | - |
dc.identifier.doi | 10.3847/1538-4357/ab99a3 | en_US |
dc.identifier.scopus | 2-s2.0-85088039042 | en_US |
dc.identifier.isi | WOS:000551775400001 | en_US |
dc.identifier.url | https://iopscience.iop.org/article/10.3847/1538-4357/ab99a3 | en_US |
dc.identifier.url | https://api.elsevier.com/content/abstract/scopus_id/85088039042 | en_US |
dc.relation.medium | STAMPA | en_US |
dc.relation.volume | 897 | en_US |
dc.relation.issue | 1 | en_US |
dc.relation.firstpage | 94 | en_US |
dc.type.referee | REF_1 | en_US |
dc.description.international | sì | 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 | 2020ApJ...897...94G | 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 | O.A. Padova | - |
crisitem.author.dept | O.A. Roma | - |
crisitem.author.dept | O.A. Trieste | - |
crisitem.author.dept | O.A. Trieste | - |
crisitem.author.dept | O.A. Trieste | - |
crisitem.author.dept | O.A. Trieste | - |
crisitem.author.dept | O.A. Roma | - |
crisitem.author.orcid | 0000-0002-5688-0663 | - |
crisitem.author.orcid | 0000-0003-0734-1273 | - |
crisitem.author.orcid | 0000-0002-4031-4157 | - |
crisitem.author.orcid | 0000-0002-2115-5234 | - |
crisitem.author.orcid | 0000-0002-6830-9093 | - |
crisitem.author.orcid | 0000-0003-4744-0188 | - |
crisitem.author.orcid | 0000-0002-4096-2680 | - |
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 | |
---|---|---|---|---|
2006.02451.pdf | preprint | 855.69 kB | Adobe PDF | View/Open |
Grazian20.pdf | [Administrators only] | 1.02 MB | Adobe PDF |
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