Relativistic blast-wave model for the rapid flux variations of AO 0235+164 and other compact radio sources

Journal Article · Fri Sep 15 04:00:00 EDT 1978 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/156430· OSTI ID:6618429

Marscher, A P

A relativisitc blast-wave model is developed which can adequately explain the observed features of flux and structural variations in compact extragalactic radio sources. The model employs a pulse of energy E/sub sig/ (a ''signal'') which strikes a ring of gas (a ''screen'') of inner radius R/sub scr/ and thickness L/sub scr/. The interaction of the signal with the gas in the screen causes a relativistically expanding blast wave to be formed, with particle acceleration and magnetic field amplification occurring near the shock front. The evolution of the resulting synchrotron emission is calculated and is shown to agree with observations of the late 1975 radio burst in the BL Lacertae object AO 0235+164 and with the observed nature of the majority of other highly variable radio sources. The combined effects of relativistic bulk motions with Lorentz factors GAMMA> or approx. =10, expansion and radiation losses of the high-energy electrons, and confinement of the screen to a thin ring result in the appearance of two distinct radio components which separate with superluminal relative velocities, v/sub sep/approx. =2GAMMAc, consistent with VLBI observations. More highly relativistic bulk motions (GAMMA> or approx. =10) cause a rapidly expanding (v/sub exp/approx. =GAMMAc) ring of emission to appear.The model overcomes the well known problems of excessive implied brightness temperatures and lack of observable inverse Compton X-ray emission, while explaining the commonly observed rapid flux and structural changes of many compact radio sources. However, the required mass and energy production rates of the central region are approximately two orders of magnitude greater than those provided by current theory.

• Research Organization: Laboratory for High Energy Astrophysics, NASA Goddard Space Flight Center
• OSTI ID: 6618429
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 224:3; 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
BREMSSTRAHLUNG
COSMIC GASES
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
FIELD THEORIES
FLUIDS
GASES
GENERAL RELATIVITY THEORY
MAGNETIC FIELDS
PLASMA
RADIATIONS
RADIOWAVE RADIATION
SHOCK WAVES
SYNCHROTRON RADIATION
VARIATIONS