Discovery of the first heavily obscured QSO candidate at <i>z</i> &gt; 6 in a close galaxy pair

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dc.contributor.authorVito, F.
dc.contributor.authorBrandt, W. N.
dc.contributor.authorBauer, F. E.
dc.contributor.authorGilli, R.
dc.contributor.authorLuo, B.
dc.contributor.authorZamorani, G.
dc.contributor.authorCalura, F.
dc.contributor.authorComastri, A.
dc.contributor.authorMazzucchelli, C.
dc.contributor.authorMignoli, M.
dc.contributor.authorNanni, R.
dc.contributor.authorShemmer, O.
dc.contributor.authorVignali, C.
dc.contributor.authorBrusa, M.
dc.contributor.authorCappelluti, N.
dc.contributor.authorCivano, F.
dc.contributor.authorVolonteri, M.
dc.date.accessioned2025-01-23T21:11:32Z
dc.date.available2025-01-23T21:11:32Z
dc.date.issued2019
dc.description.abstractWhile theoretical arguments predict that most of the early growth of supermassive black holes (SMBHs) happened during heavily obscured phases of accretion, current methods used for selecting z > 6 quasars (QSOs) are strongly biased against obscured QSOs, thus considerably limiting our understanding of accreting SMBHs during the first gigayear of the Universe from an observational point of view. We report the Chandra discovery of the first heavily obscured QSO candidate in the early universe, hosted by a close (approximate to 5 kpc) galaxy pair at z = 6.515. One of the members is an optically classified type-1 QSO, PSO167-13. The companion galaxy was first detected as a [C II] emitter by Atacama large millimeter array (ALMA). An X-ray source is significantly (P = 0.9996) detected by Chandra in the 2-5 keV band, with < 1.14 net counts in the 0.5-2 keV band, although the current positional uncertainty does not allow a conclusive association with either PSO167-13 or its companion galaxy. From X-ray photometry and hardness-ratio arguments, we estimated an obscuring column density of N-H > 2 x 10(24) cm(-2) and N-H > 6 x 10(23) cm(-2) at 68% and 90% confidence levels, respectively. Thus, regardless of which of the two galaxies is associated with the X-ray emission, this source is the first heavily obscured QSO candidate at z > 6.
dc.fuente.origenWOS
dc.identifier.doi10.1051/0004-6361/201935924
dc.identifier.eissn1432-0746
dc.identifier.issn0004-6361
dc.identifier.urihttps://doi.org/10.1051/0004-6361/201935924
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/100907
dc.identifier.wosidWOS:000480311200001
dc.language.isoen
dc.revistaAstronomy & astrophysics
dc.rightsacceso restringido
dc.subjectearly Universe
dc.subjectgalaxies: high-redshift
dc.subjectmethods: observational
dc.subjectgalaxies: individual: J167.6415-13.4960
dc.subjectgalaxies: active
dc.subjectX-rays: individuals: J167.6415-13.4960
dc.titleDiscovery of the first heavily obscured QSO candidate at <i>z</i> &gt; 6 in a close galaxy pair
dc.typeartículo
dc.volumen628
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
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