UV excess of quasars - Luminosity dependence

Journal Article · Fri May 01 04:00:00 EDT 1987 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/184891· OSTI ID:6270215

Wandel, A

The transition from the near-infrared power law to the blue bump in quasar spectra is studied by analyzing the complete sample published by Neugebauer et al. (1987). It is found that the flattening of the continuum spectrum toward the UV increases with continuum luminosity; the spectral slope between 4200 A and 7500 A (in the quasar's rest frame) is strongly correlated with luminosity and redshift. Only part of this correlation can be attributed to contamination by starlight of the host galaxy. This result is modeled in terms of an accretion disk spectrum combined with a nonthermal power law. In order to fit the data, the Eddington ratio must be in the range L(opt)/L(E) approximately 0.003-0.03(epsilon/0.1) exp -1 (epsilon being the efficiency). This parameter range also yields inner disk temperatures of (30,000-200,000 K), in accordance with the temperatures inferred from the UV excess of quasars observed with the IUE. 21 references.

• Research Organization: Stanford Univ., CA
• OSTI ID: 6270215
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 316; ISSN ASJOA
• 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
ACCRETION DISKS
BALMER LINES
BLACKBODY RADIATION
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
GALAXY NUCLEI
INFRARED RADIATION
LUMINOSITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
QUASARS
RADIATIONS
RED SHIFT
SPECTRA
ULTRAVIOLET RADIATION