A spectroscopic survey of faint quasars in the SDSS deep stripe. I. Preliminary results from the co-added catalog

Linhua Jiang, Xiaohui Fan, Richard J. Cool, Daniel J. Eisenstein, Idit Zehavi, Gordon T. Richards, Ryan Scranton, David Johnston, Michael A. Strauss, Donald P. Schneider, J. Brinkmann

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Abstract

In this paper we present the first results of a deep spectroscopic survey of faint quasars in the Sloan Digital Sky Survey (SDSS) Southern Survey, a deep survey carried out by repeatedly imaging a 270 deg 2 area. Quasar candidates were selected from the deep data with good completeness over 0 < z < 5 and 2-3 mag fainter than the SDSS main survey. Spectroscopic follow-up was carried out on the 6.5 m MMT with Hectospec. The preliminary sample of this SDSS faint quasar survey (SFQS) covers ∼3.9 deg 2, contains 414 quasars, and reaches g = 22.5. The overall selection efficiency is ∼66% (∼80% at g < 21.5); the efficiency in the most difficult redshift range (2 < z < 3) is better than 40%. We use the 1/V a method to derive a binned estimate of the quasar luminosity function (QLF) and model the QLF using maximum likelihood analysis. The best model fits confirm previous results showing that the QLF has steep slopes at the bright end and much flatter slopes (-1.25 at z ≲ 2.0 and -1.55 at z ≳ 2.0) at the faint end, indicating a break in the QLF slope. Using a luminosity-dependent density evolution model, we find that the quasar density at M g < -22.5 peaks at z ∼ 2, which is later in cosmic time than the peak of z ∼ 2.5 found from surveys of more luminous objects. The SFQS QLF is consistent with the results of the 2dF QSO Redshift Survey, the SDSS, and the 2dF-SDSS LRG and QSO Survey, but probes fainter quasars. We plan to obtain more quasars from future observations and establish a complete faint quasar sample with more than 1000 objects over 10 deg 2.

Original languageEnglish (US)
Pages (from-to)2788-2800
Number of pages13
JournalAstronomical Journal
Volume131
Issue number6
DOIs
StatePublished - Jun 2006

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quasars
catalogs
luminosity
slopes
maximum likelihood analysis
completeness
probe

Keywords

  • Galaxies: luminosity function, mass function
  • Quasars: general
  • Surveys

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Jiang, L., Fan, X., Cool, R. J., Eisenstein, D. J., Zehavi, I., Richards, G. T., ... Brinkmann, J. (2006). A spectroscopic survey of faint quasars in the SDSS deep stripe. I. Preliminary results from the co-added catalog. Astronomical Journal, 131(6), 2788-2800. https://doi.org/10.1086/503745

A spectroscopic survey of faint quasars in the SDSS deep stripe. I. Preliminary results from the co-added catalog. / Jiang, Linhua; Fan, Xiaohui; Cool, Richard J.; Eisenstein, Daniel J.; Zehavi, Idit; Richards, Gordon T.; Scranton, Ryan; Johnston, David; Strauss, Michael A.; Schneider, Donald P.; Brinkmann, J.

In: Astronomical Journal, Vol. 131, No. 6, 06.2006, p. 2788-2800.

Research output: Contribution to journalArticle

Jiang, L, Fan, X, Cool, RJ, Eisenstein, DJ, Zehavi, I, Richards, GT, Scranton, R, Johnston, D, Strauss, MA, Schneider, DP & Brinkmann, J 2006, 'A spectroscopic survey of faint quasars in the SDSS deep stripe. I. Preliminary results from the co-added catalog', Astronomical Journal, vol. 131, no. 6, pp. 2788-2800. https://doi.org/10.1086/503745
Jiang, Linhua ; Fan, Xiaohui ; Cool, Richard J. ; Eisenstein, Daniel J. ; Zehavi, Idit ; Richards, Gordon T. ; Scranton, Ryan ; Johnston, David ; Strauss, Michael A. ; Schneider, Donald P. ; Brinkmann, J. / A spectroscopic survey of faint quasars in the SDSS deep stripe. I. Preliminary results from the co-added catalog. In: Astronomical Journal. 2006 ; Vol. 131, No. 6. pp. 2788-2800.
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AU - Jiang, Linhua

AU - Fan, Xiaohui

AU - Cool, Richard J.

AU - Eisenstein, Daniel J.

AU - Zehavi, Idit

AU - Richards, Gordon T.

AU - Scranton, Ryan

AU - Johnston, David

AU - Strauss, Michael A.

AU - Schneider, Donald P.

AU - Brinkmann, J.

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N2 - In this paper we present the first results of a deep spectroscopic survey of faint quasars in the Sloan Digital Sky Survey (SDSS) Southern Survey, a deep survey carried out by repeatedly imaging a 270 deg 2 area. Quasar candidates were selected from the deep data with good completeness over 0 < z < 5 and 2-3 mag fainter than the SDSS main survey. Spectroscopic follow-up was carried out on the 6.5 m MMT with Hectospec. The preliminary sample of this SDSS faint quasar survey (SFQS) covers ∼3.9 deg 2, contains 414 quasars, and reaches g = 22.5. The overall selection efficiency is ∼66% (∼80% at g < 21.5); the efficiency in the most difficult redshift range (2 < z < 3) is better than 40%. We use the 1/V a method to derive a binned estimate of the quasar luminosity function (QLF) and model the QLF using maximum likelihood analysis. The best model fits confirm previous results showing that the QLF has steep slopes at the bright end and much flatter slopes (-1.25 at z ≲ 2.0 and -1.55 at z ≳ 2.0) at the faint end, indicating a break in the QLF slope. Using a luminosity-dependent density evolution model, we find that the quasar density at M g < -22.5 peaks at z ∼ 2, which is later in cosmic time than the peak of z ∼ 2.5 found from surveys of more luminous objects. The SFQS QLF is consistent with the results of the 2dF QSO Redshift Survey, the SDSS, and the 2dF-SDSS LRG and QSO Survey, but probes fainter quasars. We plan to obtain more quasars from future observations and establish a complete faint quasar sample with more than 1000 objects over 10 deg 2.

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