The z = 5.8 Quasar SDSSp J1044−0125: A Peek at Quasar Evolution?

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The newly discovered z = 5.8 quasar SDSSp J104433.04-012502.2 was recently detected in X-rays and found to be extremely X-ray weak. Here we present the hardness ratio analysis of the XMM-Newton observation. We consider various models to explain the detection in the soft X-ray band and nondetection in the hard band, together with its X-ray weakness. We show that the source may have a steep power-law slope, with an absorber partially covering the continuum. This may be X-ray evidence to support the recent argument of Mathur that narrow-line Seyfert 1 galaxies, which show steep power-law slopes, might be the low-redshift, low-luminosity analogs of the high-redshift quasars. Heavily shrouded and steep X-ray spectrum quasars may indeed represent the early stages of quasar evolution, and SDSSp J104433.04-012502.2 is possibly giving us a first glimpse of the physical evolution of quasar properties.



galaxies: active, galaxies: evolution, galaxies: nuclei, quasars: general, quasars: individual (SDSSp J104433.04-012502.2)


Smita Mathur, "The z = 5.8 Quasar SDSSp J1044−0125: A Peek at Quasar Evolution?" The Astronomical Journal 122, no. 4 (2001), doi:10.1086/323307