Radiation pressure in quasar clouds

Journal Article · Mon Dec 01 04:00:00 EST 1975 · Astrophys. J., v. 202, no. 2, pp. 306-318

DOI:https://doi.org/10.1086/153978· OSTI ID:4056209

McKee, C F; Tarter, C B

The effects of ionizing radiation pressure on optically thick clouds are analyzed and the results applied to quasars. An analysis shows that the radiative acceleration of a cloud is approximately-greater-than10 percent of the fully optically thin value unless the continuum optical depth is very large. The acceleration produced by line absorption is confined to the face of the cloud which is exposed to the incident flux, while the acceleration due to the continuum radiation increases inside the cloud. The disruptive effect of internally created line photons, originally studied by Williams, is analyzed for the case of an optically thick continuum, and it is found that the disruptive acceleration can be greatly enhanced and that it is anisotropic tending to blow off the back side of the cloud. Hence it is concluded that if quasar clouds are radiatively accelerated, they are optically thin; and it is shown that this result is consistent with the observations. Confinement of the clouds is discussed, and it is shown that photoionized clouds cannot be confined by radiation pressure alone. A model for absorption lines produced by numerous small clouds is developed, and it is argued that the absorption lines most likely arise outside the emission-line region. (AIP)

• Research Organization: Physics and Astronomy Departments, University of California, Berkeley
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-024047
• OSTI ID: 4056209
• Journal Information: Astrophys. J., v. 202, no. 2, pp. 306-318, Journal Name: Astrophys. J., v. 202, no. 2, pp. 306-318; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

*QUASARS-- RADIATION PRESSURE
640103* --Physics Research--Astrophysics & Cosmology--Quasi- Stellar
Radio & X-Ray Sources
ACCELERATION
COSMIC GASES
IONIZATION
N56300* --Physics (Astrophysics & Cosmology)--Quasi-stellar
Radio & X-Ray Sources
PHOTONS
RADIANT HEAT TRANSFER