Proceedings of the 33rd Herstmonceux Conference, held in Cambridge, July 6-22, 1992
Book contents
- Frontmatter
- Contents
- Index of Participants
- Preface
- I Evidence and Implications of Anisotropy in AGN
- II Luminosity Functions and Continuum Energy Distributions
- III The Broad Line Region: Variability and Structure
- IV X-rays and Accretion Disks
- V Beams, Jets and Blazars
- Magnetic Propulsion of Jets in AGN
- MHD Accretion-Ejection Model: X- and γ-rays and Formation of Relativistic Pair Beams
- Relativistic Electron Beams in AGN: Construction of Transonic Solutions
- Properties of Relativistic Jets
- A Massive Binary Black Hole in 1928+738?
- Gamma-Rays from Blazars: a Comparison of 3C 279, PKS 0537-441 and Mrk 421
- Microquasars in the Galactic Centre Region
- A Comparison of the Ultra-violet Continuum Variability Properties of Blazars and Seyfert 1s
- Simultaneous Optical and IR Monitoring of the Seyfert Nucleus NGC 7469
- Broad-Band Spectra and Polarization Properties of Variable Flat-Spectrum Radio Sources
- The Radio to Optical Variability of the BL Lac Object ON 231
- January 1992 Microvariability Campaign of OJ 287
- Blazar Microvariability: a Case Study of AO 0235+164
- Timescales of the Optical Variability of the BL Lacertae Galaxy PKS 2201+044
- Dynamics of Quasar Variability
- The Variability of a Large Sample of Quasars
- The Fate of Central Black Holes in Merging Galaxies
- Polarimetric Searching for Goldstone Bosons from AGNs
- VI Concluding Talk
A Comparison of the Ultra-violet Continuum Variability Properties of Blazars and Seyfert 1s
from V - Beams, Jets and Blazars
Published online by Cambridge University Press: 04 August 2010
Book contents
- Frontmatter
- Contents
- Index of Participants
- Preface
- I Evidence and Implications of Anisotropy in AGN
- II Luminosity Functions and Continuum Energy Distributions
- III The Broad Line Region: Variability and Structure
- IV X-rays and Accretion Disks
- V Beams, Jets and Blazars
- Magnetic Propulsion of Jets in AGN
- MHD Accretion-Ejection Model: X- and γ-rays and Formation of Relativistic Pair Beams
- Relativistic Electron Beams in AGN: Construction of Transonic Solutions
- Properties of Relativistic Jets
- A Massive Binary Black Hole in 1928+738?
- Gamma-Rays from Blazars: a Comparison of 3C 279, PKS 0537-441 and Mrk 421
- Microquasars in the Galactic Centre Region
- A Comparison of the Ultra-violet Continuum Variability Properties of Blazars and Seyfert 1s
- Simultaneous Optical and IR Monitoring of the Seyfert Nucleus NGC 7469
- Broad-Band Spectra and Polarization Properties of Variable Flat-Spectrum Radio Sources
- The Radio to Optical Variability of the BL Lac Object ON 231
- January 1992 Microvariability Campaign of OJ 287
- Blazar Microvariability: a Case Study of AO 0235+164
- Timescales of the Optical Variability of the BL Lacertae Galaxy PKS 2201+044
- Dynamics of Quasar Variability
- The Variability of a Large Sample of Quasars
- The Fate of Central Black Holes in Merging Galaxies
- Polarimetric Searching for Goldstone Bosons from AGNs
- VI Concluding Talk
Summary
Abstract
Long time scale ultraviolet light curves of blazars and Seyfert 1s both show very strong continuum variations, but this similarity vanishes when short time scales, spectral variability and correlations between variability and luminosity are studied. For instance, blazars show much more rapid variations than Seyfert 1s. Also, the spectra of Seyfert 1s harden as the source brightens, while blazars show little spectral variability. Third, the most luminous blazars tend to be the most strongly variable, while for Seyfert 1s, the strongest variations are seen in the least luminous sources. These differences suggest that in spite of some overall similarities, the observed emission from blazars and Seyfert 1s have different physical origins. These results are consistent with models which hold that the ultraviolet emission from blazars is incoherent synchrotron emission from a jet, while that from Seyfert 1s is dominated by thermal emission from an accretion disk.
Background
In the 13 years since its launch, IUE has obtained over 5000 ultraviolet spectra of active galactic nuclei (AGN). In this paper, we use ∼2500 spectra of 16 objects to survey the ultraviolet variability properties of Seyfert 1s (defined to include quasars as well; [2]) and blazars (BL Lacs and OVV quasars; [6]).
Long and Short Time Scale Variability
Although it is a common prejudice that blazars are more strongly variable than Seyfert 1s, the long term variability properties of the two types of object are actually very difficult to distinguish.
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- The Nature of Compact Objects in Active Galactic NucleiProceedings of the 33rd Herstmonceux Conference, held in Cambridge, July 6-22, 1992, pp. 389 - 392Publisher: Cambridge University PressPrint publication year: 1994
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