Details

Autor(en) / Beteiligte

• Schindler, Jan-Torge
• Fan, Xiaohui
• McGreer, Ian D.
• Yang, Jinyi
• Wang, Feige
• Green, Richard
• Garavito-Camargo, Nicolas
• Huang, Yun-Hsin
• O'Donnell, Christine
• Patej, Anna
• Pucha, Ragadeepika
• Rees, Jon M.
• Spalding, Eckhart

Titel

The Extremely Luminous Quasar Survey in the Sloan Digital Sky Survey Footprint. II. The North Galactic Cap Sample

Ist Teil von

• The Astrophysical journal, 2018-08, Vol.863 (2), p.144

Ort / Verlag

Philadelphia: The American Astronomical Society

Erscheinungsjahr

2018

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• We present the North Galactic Cap sample of the Extremely Luminous Quasar Survey (ELQS-N), which targets quasars with M1450 < −27 at 2.8 ≤ z < 5 in an area of ∼7600 deg2 of the Sloan Digital Sky Survey (SDSS) footprint with 90° < R.A. < 270°. Based on a near-infrared/infrared JKW2 color cut, the ELQS selection efficiently uses random forest methods to classify quasars and to estimate photometric redshifts; this scheme overcomes some of the difficulties of pure optical quasar selection at z 3. As a result, we retain a completeness of >70% over z ∼ 3.0-5.0 at mi 17.5, limited toward fainter magnitudes by the depth of the Two Micron All Sky Survey. The presented quasar catalog consists of a total of 270 objects, of which 39 are newly identified in this work with spectroscopy obtained at the Vatican Advanced Technology Telescope and the MMT 6.5 m telescope. In addition to the high completeness, which allowed us to discover new quasars in the already well-surveyed SDSS North Galactic Cap, the efficiency of our selection is relatively high at ∼79%. Using 120 objects of this quasar sample we are able to extend the previously measured optical quasar luminosity function (QLF) by one magnitude toward the bright end at 2.8 ≤ z ≤ 4.5. A first analysis of the QLF suggests a relatively steep bright-end slope of β −4 for this sample. This result contrasts with previous results in the same redshift range, which find a much flatter slope around β ∼ −2.5, but agrees with recent measurements of the bright-end slope at lower and higher redshifts. Our results constrain the bright-end slope at z = 2.8-4.5 to β < −2.94 with a 99% confidence.