Variability models of gamma-ray blazars

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Much observational effort has been devoted in recent years to study blazar variability across the electromagnetic spectrum. In addition to spectral and polarization information, variability data can provide stringent constraints on the radiation mechanisms, the geometry of the emission regions, beaming factors, formation and dynamics of shocks, and perhaps the jet's content. In most models the variability pattern is governed by the following timescales: i) the light travel time across the source, ii) the cooling time, iii) the acceleration or injection time of radiating particles, and iv) the dynamical time, which equals roughly the light crossing time in the case of a relativistically expanding source. It is conceivable, however, that the temporal structure observed involves additional, distinct timescales that are associated with completely different physical process, as demonstrated by other transient systems, e.g., radio pulsars, GRB; the overall pulse duration and the duty cycle in the former system reflect the rotation of a neutron star, whereas the temporal substructure (sub-pulses, polarization swings, etc.) is presumably connected with the emission mechanism. A plausible variability scenario for blazars is the formation of a train of shocks during a period of enhanced activity that might be associated with accretion instabilities or with the process responsible for the ejection of the jet. Such a possibility seems to be suggested by some recent observations which reveal, what appears to be rapid flaring during the occurrence of a much longer outburst (Wagner 1998).
Original languageEnglish
Title of host publicationAstronomical Society of the Pacific Conference Series
Place of PublicationUSA
Pages471 - 4
Volume159
StatePublished - 1999

Keywords

  • astrophysical radiation mechanisms
  • BL Lac-type objects
  • gamma-ray sources (astronomical)
  • quasars

Fingerprint

Dive into the research topics of 'Variability models of gamma-ray blazars'. Together they form a unique fingerprint.

Cite this