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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 660837.0, MPI für Astronomie / Publikationen_mpia
The dust emission of high-redshift quasars
Authors:Leipski, C.; Meisenheimer, K.
Date of Publication (YYYY-MM-DD):2012-01
Journal Abbrev.:Journal of Physics Conference Series
Issue / Number:1
Start Page:012037
Audience:Not Specified
Abstract / Description:The detection of powerful near-infrared emission in high redshift (z > 5) quasars demonstrates that very hot dust is present close to the active nucleus also in the very early universe. A number of high-redshift objects even show significant excess emission in the rest frame NIR over more local AGN spectral energy distribution (SED) templates. In order to test if this is a result of the very high luminosities or redshifts, we construct mean SEDs from the latest SDSS quasar catalogue in combination with MIR data from the WISE preliminary data release for several redshift and luminosity bins. Comparing these mean SEDs with a large sample of z > 5 quasars we could not identify any significant trends of the NIR spectral slope with luminosity or redshift in the regime 2.5 < z lesssim 6 and 1045 < νLν (1350Å) lesssim 1047 erg/s. In addition to the NIR regime, our combined Herschel and Spitzer photometry provides full infrared SED coverage of the same sample of z > 5 quasars. These observations reveal strong FIR emission (LFIR gtrsim 1013 Lodot) in seven objects, possibly indicating star-formation rates of several thousand solar masses per year. The FIR excess emission has unusally high temperatures (T~65K) which is in contrast to the temperature typically expected from studies at lower redshift (T~45K). These objects are currently being investigated in more detail.
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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