Excess 2 centimeter emission - a new continuum component in the spectra of radio-quiet quasars

Journal Article · Thu Sep 01 00:00:00 EDT 1988 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/185256· OSTI ID:6685096

Antonucci, R; Barvainis, R

The centimeter and millimeter regions of the spectra of radio-quiet quasars and luminous Seyfert 1 nuclei are examined. It is found that steep-spectrum optically thin synchrotron radiation dominates in the 20 cm to 6 cm region of most objects. A flat or rising component which becomes dominant by 2 cm in nine of the 17 cases in the sample is identified as a new continuum component called the high-frequency excess (HFE). The luminous quasar PG 1634 + 706, for which HFE dominates throughout the centimeter region, is discussed in detail. Possible causes of the HFE include self-absorbed synchrotron sources, about 10 to the 6 K nuclear free-free sources, and about 1000 K free-free sources from associated nuclear starbursts. It is concluded that because the brightness temperature predictions are very distinct, future observations will determine which explanation is correct. 27 references.

• Research Organization: Space Telescope Science Institute, Baltimore, MD (USA); National Radio Astronomy Observatory, Charlottesville, VA (USA); Haystack Observatory, Westford, MA (USA)
• OSTI ID: 6685096
• Journal Information: Astrophys. J.; (United States), Vol. 332
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
GALAXY NUCLEI
MICROWAVE SPECTRA
QUASARS
SEYFERT GALAXIES
ENERGY SPECTRA
RADIOWAVE RADIATION
SYNCHROTRON RADIATION
BREMSSTRAHLUNG
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
GALAXIES
RADIATIONS
SPECTRA
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources
640105 - Astrophysics & Cosmology- Galaxies