A Near‐Infrared Spectral Template for Quasars

We present a near-infrared quasar composite spectrum spanning the wavelengthrange 0.58 - 3.5 um. The spectrum has been constructed from observations of 27quasars obtained at the NASA IRTF telescope and satisfying the criteria Ks <14.5 and Mi < -23; the redshift range is 0.118 < z < 0.418. The signal-to-noiseis moderate, reaching a maximum of 150 between 1.6 and 1.9 um. While apower-law fit to the continuum of the composite spectrum requires two breaks, asingle power-law slope of alpha=-0.92 plus a 1260 K blackbody provides anexcellent description of the spectrum from H-alpha to 3.5 um, stronglysuggesting the presence of significant quantities of hot dust in thisblue-selected quasar sample. We measure intensities and line widths for tenlines, finding that the Paschen line ratios rule out Case B recombination. Wecompute K-corrections for the J, H, K, and Spitzer 3.6 um bands which will beuseful in analyzing observations of quasars up to z=10.Comment: 39 pages, 11 figures, accepted for publication in ApJ Spectra will be made available in the online version of the journal, once published. Until then, if you wish to obtain the composite spectrum send an email request to eilatg[at]astro.columbia.ed