<i>Chandra</i> and <i>Magellan</i>/FIRE follow-up observations of PSO167-13: An X-ray weak QSO at <i>z</i>=6.515

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dc.contributor.authorVito, F.
dc.contributor.authorBrandt, W. N.
dc.contributor.authorRicci, F.
dc.contributor.authorCongiu, E.
dc.contributor.authorConnor, T.
dc.contributor.authorBanados, E.
dc.contributor.authorBauer, F. E.
dc.contributor.authorGilli, R.
dc.contributor.authorLuo, B.
dc.contributor.authorMazzucchelli, C.
dc.contributor.authorMignoli, M.
dc.contributor.authorShemmer, O.
dc.contributor.authorVignali, C.
dc.contributor.authorCalura, F.
dc.contributor.authorComastri, A.
dc.contributor.authorDecarli, R.
dc.contributor.authorGallerani, S.
dc.contributor.authorNanni, R.
dc.contributor.authorBrusa, M.
dc.contributor.authorCappelluti, N.
dc.contributor.authorCivano, F.
dc.contributor.authorZamorani, G.
dc.date.accessioned2025-01-20T22:19:15Z
dc.date.available2025-01-20T22:19:15Z
dc.date.issued2021
dc.description.abstractContext. The discovery of hundreds of quasi-stellar objects (QSOs) in the first gigayear of the Universe powered by already grown supermassive black holes (SMBHs) challenges our knowledge of SMBH formation. In particular, investigations of z>6 QSOs that present notable properties can provide unique information on the physics of fast SMBH growth in the early Universe.Aims. We present the results of follow-up observations of the z=6.515 radio-quiet QSO PSO167-13, which is interacting with a close companion galaxy. The PSO167-13 system has recently been proposed to host the first heavily obscured X-ray source at high redshift. The goals of these new observations are to confirm the existence of the X-ray source and to investigate the rest-frame UV properties of the QSO.Methods. We observed the PSO167-13 system with Chandra/ACIS-S (177 ks) and obtained new spectroscopic observations (7.2 h) with Magellan/FIRE.Results. No significant X-ray emission is detected from the PSO167-13 system, suggesting that the obscured X-ray source previously tentatively detected was either due to a strong background fluctuation or is highly variable. The upper limit (90% confidence level) on the X-ray emission of PSO167-13 (L2-10 keV<8.3x10(43) erg s(-1)) is the lowest available for a z>6 QSO. The ratio between the X-ray and UV luminosity of alpha (ox)<-1.95 makes PSO167-13 a strong outlier from the <alpha>(ox)-L-UV and L-X-L-bol relations. In particular, its X-ray emission is more than six times weaker than the expectation based on its UV luminosity. The new Magellan/FIRE spectrum of PSO167-13 is strongly affected by unfavorable sky conditions, but the tentatively detected C IV and Mg II emission lines appear strongly blueshifted.Conclusions. The most plausible explanations for the X-ray weakness of PSO167-13 are intrinsic weakness or small-scale absorption by Compton-thick material. The possible strong blueshift of its emission lines hints at the presence of nuclear winds, which could be related to its X-ray weakness.
dc.fuente.origenWOS
dc.identifier.doi10.1051/0004-6361/202140399
dc.identifier.eissn1432-0746
dc.identifier.issn0004-6361
dc.identifier.urihttps://doi.org/10.1051/0004-6361/202140399
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/94591
dc.identifier.wosidWOS:000658288400004
dc.language.isoen
dc.revistaAstronomy & astrophysics
dc.rightsacceso restringido
dc.subjectearly Universe
dc.subjectgalaxies: active
dc.subjectgalaxies: high-redshift
dc.subjectmethods: observational
dc.subjectgalaxies: individual: J167
dc.subject6415-134960
dc.subjectX-rays: individuals: J167
dc.subject6415-134960
dc.title<i>Chandra</i> and <i>Magellan</i>/FIRE follow-up observations of PSO167-13: An X-ray weak QSO at <i>z</i>=6.515
dc.typeartículo
dc.volumen649
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
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