Utilizza questo identificativo per citare o creare un link a questo documento:
http://hdl.handle.net/20.500.12386/35145
Campo DC | Valore | Lingua |
---|---|---|
dc.contributor.author | Pascal M. Keller | en_US |
dc.contributor.author | Nithyanandan Thyagarajan | en_US |
dc.contributor.author | Ajay Kumar | en_US |
dc.contributor.author | Nissim Kanekar | en_US |
dc.contributor.author | BERNARDI, Gianni | en_US |
dc.date.accessioned | 2024-05-29T08:38:40Z | - |
dc.date.available | 2024-05-29T08:38:40Z | - |
dc.date.issued | 2024 | en_US |
dc.identifier.issn | 0035-8711 | en_US |
dc.identifier.uri | http://hdl.handle.net/20.500.12386/35145 | - |
dc.description.abstract | Quasars at redshifts $z>6$ are an excellent probe of the formation and evolution of supermassive black holes in the early Universe. The population of radio-luminous quasars is of particular interest, as such quasars could potentially be used to study the neutral intergalactic medium during cosmic reionisation via H$\,$I 21$\,$cm absorption studies. However, the lack of deep radio observations of $z>6$ quasars leaves the population poorly constrained, and suitable candidates for an H$\,$I 21$\,$cm absorption study have yet to be found. In this work, we present Jansky Very Large Array (VLA) 1$-$2 GHz radio continuum observations of 138 quasars at redshifts $6.0 \leq z<7.6$. We detect the radio continuum emission of the $z=6.1$ quasar J1034-1425, with a 1.6 GHz flux density of $170\pm 36\,\mu$Jy. This quasar is radio-quiet with radio-loudness, $R \equiv f_{5\text{~GHz}}/f_{\nu,\text{4400 A}} = 2.4\pm0.5$. In addition, we detect 7 other quasars at z>6, which have previously been characterised in the literature at these frequencies. Using the full sample, we estimate the radio-loud fraction to be $3.8^{+6.2}_{-2.4}\%$, where the uncertainties are 95% confidence intervals. This is lower than recent estimates of the radio-loud fraction in the literature, but is still marginally consistent with no redshift evolution of the radio-loud fraction. We explore the undetected quasar population by stacking their continuum images at their optical positions and obtain a median stacked flux density of $13.8\pm 3.9~\mu$Jy and luminosity of $\log{L_{5~\mathrm{GHz}}/(\mathrm{W~Hz}^{-1})}=24.2\pm0.1$. | en_US |
dc.language.iso | eng | en_US |
dc.title | The radio-loud fraction of quasars at z > 6 | en_US |
dc.type | Article | - |
dc.identifier.doi | 10.1093/mnras/stae418 | en_US |
dc.identifier.scopus | 2-s2.0-85185402350 | en_US |
dc.identifier.url | https://academic.oup.com/mnras/article/528/4/5692/7604003 | en_US |
dc.identifier.url | http://arxiv.org/abs/2402.08732v1 | en_US |
dc.relation.medium | STAMPA | en_US |
dc.relation.volume | 528 | en_US |
dc.relation.issue | 4 | en_US |
dc.relation.firstpage | 5692 | en_US |
dc.relation.lastpage | 5702 | en_US |
dc.type.referee | REF_1 | en_US |
dc.description.international | sì | en_US |
dc.contributor.country | ITA | en_US |
dc.contributor.country | GBR | en_US |
dc.contributor.country | AUS | en_US |
dc.contributor.country | IND | 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 | - |
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.grantfulltext | open | - |
item.cerifentitytype | Publications | - |
item.openairetype | Article | - |
item.openairecristype | http://purl.org/coar/resource_type/c_18cf | - |
item.fulltext | With Fulltext | - |
item.languageiso639-1 | en | - |
crisitem.journal.journalissn | 0035-8711 | - |
crisitem.journal.ance | E112946 | - |
crisitem.author.dept | IRA Bologna | - |
crisitem.author.orcid | 0000-0002-0916-7443 | - |
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