An X-ray-selected active galactic nucleus at z = 4.6 Discovered by the cyder survey

Ezequiel Treister, Francisco J. Castander, Thomas J. Maccarone, David Herrera, Eric Gawiser, José Maza, Paolo S. Coppi

Research output: Contribution to journalReview articlepeer-review

4 Scopus citations


We present the discovery of a high-redshift, X-ray-selected active galactic nucleus (AGN) by the Calan-Yale Deep Extragalactic Research (CYDER) survey: CXOCY J033716.7-050153, located at z = 4.61, the second high-redshift AGN discovered by this survey. Here we present its optical, near-IR, and X-ray properties and compare it with other optical and X-ray-selected high-redshift AGNs. The optical luminosity of this object is significantly lower than most optically selected high-redshift quasars. It also has a lower rest-frame UV to X-ray emission ratio than most known quasars at this redshift. This mild deviation can be explained either by dust obscuring the UV radiation of a normal radio-quiet AGN emitting at 10% of its Eddington luminosity or because this is intrinsically a low-luminosity radio-loud AGN with a supermassive black hole of ∼108 M emitting at 1% of its Eddington luminosity. Deep radio observations can discriminate between these two hypotheses.

Original languageEnglish
Pages (from-to)36-41
Number of pages6
JournalAstrophysical Journal
Issue number1 I
StatePublished - Mar 1 2004


  • Galaxies: active
  • Quasars: individual (CXOCY J033716.7-050153)
  • X-rays: galaxies


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