A Near-Infrared Spectral Template for Quasars

We present a near-infrared quasar composite spectrum spanning the wavelength range 0.58-3.5 μm. The spectrum has been constructed from observations of 27 quasars obtained at the NASA IRTF telescope and satisfying the criteria K_s<14.5 and M_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 μm. While a power-law fit to the continuum of the composite spectrum requires two breaks, a single power-law slope of α=-0.92 plus a 1260 K blackbody provides an excellent description of the spectrum from Hα to 3.5 μm, 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 μm bands, which will be useful in analyzing observations of quasars up to z=10.