Quenchings and outbursts of extragalactic radio sources - Nine years of 3.3-mm measurements and comparisons with centimeter-wave variations

Epstein, E. E.; Schneider, E.; Fogarty, W. G.; Mottmann, John

doi:10.1086/113118

Cited by 14 publications

(6 citation statements)

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“…The radio data were obtained at the University of Michigan Radio Observatory , at Haystack Observatory, at the NRAO (Balonek 1982;Johnston et al 1984), and with the Aerospace 4.6 m millimeter wave telescope (Epstein et al 1982). Figure 1 shows that the behavior of the flux densities in the different radio bands is quite similar, and this leads to similar structure functions.…”

Section: B) Radio Datamentioning

confidence: 96%

Multifrequency observations of BL Lacertae

Bregman

Glassgold

Huggins

et al. 1990

ApJ

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We present 20 years of optical, infrared, and radio monitoring data for BL Lac as well as four simultaneous multifrequency spectra covering the 10 9-10 18 Hz range. Although there is no time delay between the optical and infrared variability, the high-frequency radio variations precede lower frequency variations, but only by weeks. The optical variability precedes the radio variability by a few years. The structure function for the radio variations is nearly that of shot noise for time scales less than 600 days, in contrast to the optical variation, which is similar to flicker noise. These results indicate that, although there are fundamental differences between the optical and radio emitting regions, they are related, possibly by the propagation of shocks between regions. The multifrequency spectra show that the power per logarithmic bandwidth has a well-defined peak in the near-infrared and a sharp cutoff in the optical-ultraviolet region. This cutoff is like those seen in a few other blazars and is attributed to synchrotron losses that prevent particle acceleration from exceeding a critical energy. The X-ray continuum is not smoothly connected to the optical-ultraviolet emission and has a flatter slope, similar to that of the infrared-millimeter region. In addition, the X-ray emission varied in the same sense as the infrared-millimeter emission but opposite that of the optical-ultraviolet emission. These X-ray properties are those expected from the synchrotron-self-Compton process. The best model suggests that the plasma radiating at ~ 10 1 1. 5 Hz has a size of ~ 10-2 • 5 pc, a Doppler parameter off>= 2-3, and a magnetic field of B = 2-40 G.

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Section: B) Radio Datamentioning

confidence: 96%

Multifrequency observations of BL Lacertae

Bregman

Glassgold

Huggins

et al. 1990

ApJ

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“…Characteristic variability timescales can be determined from the radio through the X-ray region. The characteristic timescale of radio flux variation is approximately years in the 10s-109Hz region, months-years in the 109-101~ Hz region, and weeks-months in the 0.4-1 x 1011 Hz region (Flett and Henderson 1981;Altschuler 1982Altschuler , 1983Epstein et al 1982;Balonek 1982;Johnston et al 1984;Aller et al 1985;Botti and Abraham 1987;Fiedler et al 1987;Pustil'nik and Aliakberov 1987;Terasranta et al 1987;O'Dell 1988;Valtaoja et al 1988; see review by Altschuler 1989); cm radio source variability of an intrinsic nature should not to be confused with the daily variations, which are likely to have an extrinsic origin due to scintillation by interstellar clouds (Heeschen et al 1987). Far infrared flux variations, as defined by the relatively small number of pointed IRAS observations, are found to exist for only a few blazars; the timescale is several weeks (Impey and Neugebauer 1988).…”

Section: Inhomogeneity Of the Jetmentioning

confidence: 99%

Continuum radiation from active galactic nuclei

Bregman

1990

The Astron Astrophys Rev

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“…Many, but not all, sources in each mass range also have relativistic jets, typically seen through radio observations (see Fender 2003 for a review of the radio properties of X‐ray binaries and chapter 2 of Krolik 1999 for a brief introduction to the broad‐band properties of active galactic nuclei). Quenching of these radio jets – defined to be a rather sudden drop in the radio emission – has been known about for some time, both in certain classes of active galactic nuclei (AGN; Epstein et al 1982) and in certain X‐ray binaries (Tananbaum et al 1972; Waltman et al 1996; Harmon et al 1997; Fender et al 1999).…”

Section: Introductionmentioning

confidence: 99%

The connection between radio-quiet active galactic nuclei and the high/soft state of X-ray binaries

Maccarone¹,

Gallo

Fender

2003

Monthly Notices RAS

175

176

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A large sample of active galactic nuclei (AGN) studied here shows a ‘quenching’ of the radio emission that occurs when the luminosity is from a few per cent to about 10 per cent of the Eddington rate, just as is seen in the high/soft state of X‐ray binaries. The result holds even when the sample of AGN includes no narrow line Seyfert 1 galaxies (the systems most commonly suggested to be the analogue of the high/soft state). This adds substantially to the body of evidence that AGN show the same spectral state phenomenology and related disc–jet coupling as the stellar mass accreting black holes. That the power‐law correlation between X‐ray and radio luminosity is the same in both AGN and X‐ray binaries and extends below 10−7LEDD strengthens the argument that there is no fundamental difference between the low/hard state and the so‐called quiescent state in X‐ray binaries. We also discuss possible reasons for the scatter in the radio to X‐ray luminosity correlation in the AGN.

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Quenchings and outbursts of extragalactic radio sources - Nine years of 3.3-mm measurements and comparisons with centimeter-wave variations

Cited by 14 publications

References 0 publications

Multifrequency observations of BL Lacertae

Multifrequency observations of BL Lacertae

Continuum radiation from active galactic nuclei

The connection between radio-quiet active galactic nuclei and the high/soft state of X-ray binaries

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