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We analyze the near-infrared to UV data of 16 quasars with redshifts rangingfrom 0.71 $<$ $z$ $<$ 2.13 to investigate dust extinction properties. Thesample presented in this work is obtained from the High $A_V$ Quasar (HAQ)survey. The quasar candidates were selected from the Sloan Digital Sky Survey(SDSS) and the UKIRT Infrared Deep Sky Survey (UKIDSS), and follow-upspectroscopy was carried out at the Nordic Optical Telescope (NOT) and the NewTechnology Telescope (NTT). To study dust extinction curves intrinsic to thequasars, from the HAQ survey we selected 16 cases where the Small MagellanicCloud (SMC) law could not provide a good solution to the spectral energydistributions (SEDs). We derived the extinction curves using Fitzpatrick &Massa 1986 (FM) law by comparing the observed SEDs to the combined quasartemplate from Vanden Berk et al. 2001 and Glikman et al. 2006. The derivedextinction, $A_V$, ranges from 0.2-1.0 mag. All the individual extinctioncurves of our quasars are steeper ($R_V=2.2$-2.7) than that of the SMC, with aweighted mean value of $R_V=2.4$. We derive an `average quasar extinctioncurve' for our sample by fitting SEDs simultaneously by using the weighted meanvalues of the FM law parameters and a varying $R_V$. The entire sample is wellfit with a single best-fit value of $R_V=2.2\pm0.2$. The `average quasarextinction curve' deviates from the steepest Milky Way and SMC extinctioncurves at a confidence level $\gtrsim95\%$. Such steep extinction curvessuggest a significant population of silicates to produce small dust grains.Moreover, another possibility could be that the large dust grains may have beendestroyed by the activity of the nearby active galactic nuclei (AGN), resultingin steep extinction curves.

Extinction curve template for intrinsically reddened quasars