A near-infrared spectral template for quasars

We present a near-infrared quasar composite spectrum spanning the wavelength range 0.58-3.5 mu m. 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 mu m. While a power-law fit to the continuum of the composite spectrum requires two breaks, a single power-law slope of alpha =-0.92 plus a 1260K blackbody provides an excellent description of the spectrum from H alpha to 3.5 mu m, 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 mu m bands, which will be useful in analyzing observations of quasars up to z = 10.