The origin of the near-infrared emission in Palomar Green Quasars - The case for hot dust

Journal Article · Tue May 01 04:00:00 EDT 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/168674· OSTI ID:6712102

Berriman, G ^[1]

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1. Steward Observatory, Tucson, AZ (USA)

This paper uses the variation with redshift of the near-infrared colors of the Palomar Green Bright Quasars as the basis for an analysis of the origin of their infrared light. Comparison of the data with simple models of the continuum, appropriately redshifted, show that the flux ratios start to decline when blue optical emission is redshifted into the infrared bandpasses. The rise in vFv(2.2 microns)/vFv(1.65 microns) is attributable to the declining importance of starlight. The range of vFv(2.2 microns)/vFv(1.65 microns) at maximum is attributable to a nonthermal emission only if it has an unusually steep range of spectra, with alpha = -1.7 on average and alpha = -2.2 in the extreme. At the same time, this emission does not vary and is unpolarized. Such a combination of properties has not been seen in any known nonthermal source. Emission from hot dust, probably from a broad range of temperatures centered near 1000 K, is a much simpler interpretation. It supplies on average 25 percent of the total 2.2 microns light at z = 0 and 35 percent in the extreme. 42 refs.

• OSTI ID: 6712102
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 354; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPARATIVE EVALUATIONS
COSMIC DUST
COSMIC RADIO SOURCES
DUSTS
ELECTROMAGNETIC RADIATION
EMISSION SPECTRA
GALAXIES
INFRARED RADIATION
INFRARED SPECTRA
MATHEMATICAL MODELS
NEAR INFRARED RADIATION
ORIGIN
QUASARS
RADIATIONS
RED SHIFT
SEYFERT GALAXIES
SPECTRA