Statistical evidence for accretion disks in active galactic nuclei

Abstract

view Abstract Citations References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Statistical Evidence for Accretion Disks in Active Galactic Nuclei Caditz, David Abstract Measured U - B colors and B-magnitudes are good indicators of the shape and strength of thermal continuum spectra of active galactic nuclei (AGNs) over a limited range of redshifts, 0.4 < z < 0.75. The distribution of colors and magnitudes of a sample of 207 quasars is investigated. It is found that AGNs occupy a well-defined region of the color-magnitude plane defined by a low color limit and a magnitude- dependent high color limit. These limits are inherent in the quasar distribution and are not artificially introduced by survey selection effects or any known correlation between nonthermal spectral components and magnitude. Colors and magnitudes expected for thin accretion disks are calculated for a distribution of accretion rates and central masses. It is found that the standard thin accretion disk model accurately replicates the observed quasar color-magnitude distribution, and that the low and high color cutoffs are determined by the Eddington limit and a maximum central mass M ~ 10^9.5^ M_sun_, respectively. This result provides new evidence that accretion disks are the primary power source in AGNs. Publication: The Astrophysical Journal Pub Date: July 1993 DOI: 10.1086/172810 Bibcode: 1993ApJ...411..103C Keywords: Accretion Disks; Active Galactic Nuclei; Color-Magnitude Diagram; Red Shift; Statistical Analysis; Cataclysmic Variables; Gravitational Effects; Pre-Main Sequence Stars; T Tauri Stars; X Ray Binaries; Astrophysics; ACCRETION; ACCRETION DISKS; GALAXIES: ACTIVE; GALAXIES: NUCLEI full text sources ADS |