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Authordc.contributor.authorShemmer, Ohad 
Authordc.contributor.authorBrandt, W. N. es_CL
Authordc.contributor.authorPaolillo, Maurizio es_CL
Authordc.contributor.authorKaspi, Shai es_CL
Authordc.contributor.authorVignali, Cristian es_CL
Authordc.contributor.authorStein, Matthew S. es_CL
Authordc.contributor.authorLira Teillery, Paulina es_CL
Authordc.contributor.authorSchneider, Donald P. es_CL
Authordc.contributor.authorGibson, Robert R. es_CL
Admission datedc.date.accessioned2014-12-30T13:28:55Z
Available datedc.date.available2014-12-30T13:28:55Z
Publication datedc.date.issued2014
Cita de ítemdc.identifier.citationThe Astrophysical Journal, 783:116 (18pp), 2014 March 10en_US
Identifierdc.identifier.otherDOI: 10.1088/0004-637X/783/2/116
Identifierdc.identifier.urihttps://repositorio.uchile.cl/handle/2250/126850
General notedc.descriptionArtículo de publicación ISIen_US
Abstractdc.description.abstractWe present initial results from an exploratory X-ray monitoring project of two groups of comparably luminous radio-quiet quasars (RQQs). The first consists of four sources at 4.10 z 4.35, monitored by Chandra, and the second is a comparison sample of three sources at 1.33 z 2.74, monitored by Swift. Together with archival X-ray data, the total rest-frame temporal baseline spans ∼2–4 yr and ∼5–13 yr for the first and second group, respectively. Six of these sources show significant X-ray variability over rest-frame timescales of ∼102–103 days; three of these also show significant X-ray variability on rest-frame timescales of ∼1–10 days. The X-ray variability properties of our variable sources are similar to those exhibited by nearby and far less luminous active galactic nuclei (AGNs). While we do not directly detect a trend of increasing X-ray variability with redshift, we do confirm previous reports of luminous AGNs exhibiting X-ray variability above that expected from their luminosities, based on simplistic extrapolation from lower luminosity sources. This result may be attributed to luminous sources at the highest redshifts having relatively high accretion rates. Complementary UV–optical monitoring of our sources shows that variations in their optical–X-ray spectral energy distribution are dominated by the X-ray variations. We confirm previous reports of X-ray spectral variations in one of our sources, HS 1700+6416, but do not detect such variations in any of our other sources in spite of X-ray flux variations of up to a factor of ∼4. This project is designed to provide a basic assessment of the X-ray variability properties of RQQs at the highest accessible redshifts that will serve as a benchmark for more systematic monitoring of such sources with future X-ray missions.en_US
Lenguagedc.language.isoenen_US
Publisherdc.publisherThe American Astronomical Societyen_US
Type of licensedc.rightsAttribution-NonCommercial-NoDerivs 3.0 Chile*
Link to Licensedc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/cl/*
Keywordsdc.subjectGalaxies: activeen_US
Títulodc.titleExploratory X-ray monitoring of luminous radio-quiet quasars at high redshift: initial resultsen_US
Document typedc.typeArtículo de revista


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Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivs 3.0 Chile