Discovery of eight z ~ 6 quasars from Pan-STARRS1

May 15, 2014
16 pages
Published in:
  • Astron.J. 148 (2014) 14
e-Print:

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Abstract: (arXiv)
High-redshift quasars are currently the only probes of the growth of supermassive black holes and potential tracers of structure evolution at early cosmic time. Here we present our candidate selection criteria from the Panoramic Survey Telescope & Rapid Response System 1 and follow-up strategy to discover quasars in the redshift range 5.75.7 by more than 10%. We additionally recovered 18 previously known quasars. The eight quasars presented here span a large range of luminosities (-27.3 < M_{1450} < -25.4; 19.6 < z_ps1 < 21.2) and are remarkably heterogeneous in their spectral features: half of them show bright emission lines whereas the other half show a weak or no Lyα\alpha emission line (25% with rest-frame equivalent width of the Lyα\alpha + Nv line lower than 15{\AA}). We find a larger fraction of weak-line emission quasars than in lower redshift studies. This may imply that the weak-line quasar population at the highest redshifts could be more abundant than previously thought. However, larger samples of quasars are needed to increase the statistical significance of this finding.
Note:
  • AJ in press, 16 pages, 5 figures, 7 tables