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- Title
THE ACCRETION GEOMETRY IN RADIO-LOUD ACTIVE GALAXIES.
- Authors
BALLANTYNE, D. R.
- Abstract
We review the latest attempts to determine the accretion geometry in radio-loud active galactic nuclei (AGN). These objects, which comprise ~ 10–20% of the AGN population, produce powerful collimated radio jets that can extend thousands of parsecs from the center of the host galaxy. Recent multiwavelength surveys have shown that radio-loudness is more common in low-luminosity AGN than in higher luminosity Seyfert galaxies or quasars. These low-luminosity AGN have small enough accretion rates that they are most likely accreting via a geometrically thick and radiatively inefficient accretion flow. In contrast, X-ray spectroscopic observations of three higher luminosity broad-line radio galaxies (3C 120, 4C+74.26 and PG 1425+267) have found evidence for an untruncated thin disk extending very close to the black hole. These tentative detections indicate that, for this class of radio-loud AGN, the accretion geometry is very similar to their radio-quiet counterparts. These observations suggest that there are three conditions to jet formation that must be satisfied: the presence of a rapidly spinning black hole, an accretion flow with a large H/r ratio, and a favorable magnetic field geometry.
- Subjects
ACCRETION (Astrophysics); ACTIVE galactic nuclei; RADIO galaxies; GEOMETRIC quantization; RADIO noise; RADIO sources (Astronomy); ATMOSPHERIC radio refractivity; SPECTROSCOPIC imaging; SEYFERT galaxies; QUASARS; SUPERMASSIVE black holes
- Publication
Modern Physics Letters A, 2007, Vol 22, Issue 32, p2397
- ISSN
0217-7323
- Publication type
Article
- DOI
10.1142/S0217732307024322