A Near-Infrared Spectral Template for Quasars

• Published in: The Astrophysical journal Vol. 640; no. 2; pp. 579 - 591
• Main Authors: Glikman, Eilat, Helfand, David J, White, Richard L
• Format: Journal Article
• Language: English
• Published: Chicago, IL IOP Publishing 01-04-2006; University of Chicago Press
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; Quasars; quasars: emission lines; quasars: general; Emission line
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1086/500098

We present a near-infrared quasar composite spectrum spanning the wavelength range 0.58-3.5 km. The spectrum has been constructed from observations of 27 quasars obtained at the NASA IRTF telescope and satisfying the criteria K sub(S) < 14.5 and M sub(i) < -23; the redshift range is 0.118 < z < 0.418. The signal-to-noise ratio is moderate, reaching a maximum of 150 between 1.6 and 1.9 km. While a power-law fit to the continuum of the composite spectrum requires two breaks, a single power-law slope of a = -0.92 plus a 1260 K blackbody provides an excellent description of the spectrum from Ha to 3.5 km, strongly suggesting the presence of significant quantities of hot dust in this blue-selected quasar sample. We measure intensities and line widths for 10 lines, finding that the Paschen line ratios rule out case B recombination. We compute K-corrections for the J, H, K, and Spitzer 3.6 km bands, which will be useful in analyzing observations of quasars up to z = 10.