2000/01/27 by Belinda J. Wilkes, B. J. Wilkes, E. J. Hooper +25
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Scientific Research and Discoveries #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0001488
8 pages, 3 figures (2 color), to be published in the Springer Lecture Notes of Physics Series as part of the proceedings for "ISO Surveys of a Dusty Universe," a workshop held at Ringberg Castle, Germany, November 8 - 12, 1999. Requires latex style files for this series: cl2emult.cls, cropmark.sty, lnp.sty, sprmindx.sty, subeqnar.sty (included with submission)
arxiv created 2000/01/27 · openalex publication_date 2000/01/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The NASA/ISO Key Project on active galactic nuclei (AGN) seeks to better understand the broad-band spectral energy distributions (SEDs) of these sources from radio to X-rays, with particular emphasis on infrared properties. The ISO sample includes a wide variety of AGN types and spans a large redshift range. Two subsamples are considered herein: 8 high-redshift (1 < z < 4.7) quasars; and 22 hard X-ray selected sources. The X-ray selected AGN show a wide range of IR continuum shapes, extending to cooler colors than the optical/radio sample of Elvis et al. (1994). Where a far-IR turnover is clearly observed, the slopes are < 2.5 in all but one case so that non-thermal emission remains a possibility. The highest redshift quasars show extremely strong, hot IR continua requiring ~ 100 solar masses of 500 - 1000 Kelvin dust with ~ 100 times weaker optical emission. Possible explanations for these unusual properties include: reflection of the optical light from material above/below a torus; strong obscuration of the optical continuum; or an intrinsic deficit of optical emission.