Studies of BL Lacertae objects with the Einstein X-ray observatory: The absolute volume density

Journal Article · Tue Mar 15 04:00:00 EST 1983 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/160793· OSTI ID:5895359

Schwartz, D A; Ku, W H

We estimate that the local volume density of BL Lac objects which emit greater than 10/sup 44/ ergs s/sup -1/ in the 0.5--4.5 keV band is about 10/sup -7/ Mpc/sup -3/. This is based on identifications of bright X-ray sources, and the fact that Einstein X-ray observations detect BL Lac objects over a wide, continuous range of flux up to the thresholds of the all-sky X-ray surveys. Since this density is of the same order of magnitude as the local density of Seyfert galaxies, or local density of optically selected quasars, emitting X-rays at the same luminosity, we argue that the difference between these particular astronomical classifications is not solely due to the orientation of a relativistic beam.

• OSTI ID: 5895359
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 266:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640103* -- Astrophysics & Cosmology-- Quasi-Stellar
Radio
& X-Ray Sources-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BL LACERTAE OBJECTS
COSMIC RADIO SOURCES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DISTRIBUTION
ELECTROMAGNETIC RADIATION
GALAXIES
IONIZING RADIATIONS
LUMINOSITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
QUASARS
RADIATIONS
SEYFERT GALAXIES
SPATIAL DISTRIBUTION
X RADIATION