Search for X-ray emission from bursting radio sources

Marscher, A. P.; Marshall, F. E.; Mushotzky, R. F.; Dent, W. A.; Balonek, T. J.; Hartman, M. F.

doi:10.1086/157409

Cited by 47 publications

(46 citation statements)

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“…This is surprising since Mrk231 is formally a radio-quiet quasar, and more precisely, a BALQSO in which the radio jets are typically suppressed (although see Becker et al 1997). Given a time variability brightness temperature of T b = (12.4 ± 3.5)×10 12 K and the need to avoid the inverse Compton catastrophe (Marscher et al 1979;Ghosh & Punsly 2007), Reynolds et al (2009Reynolds et al ( , 2013 constrained the jet angle to be less than θ max = -+ 25.6 2.2 3.2 from the line of sight. This implies a nearly face-on view of the inner accretion disk, assuming the jet is directed along the rotation axis of the inner disk.…”

Section: Physical Model-revisitedmentioning

confidence: 99%

The Complete Ultraviolet Spectrum of the Archetypal “Wind-Dominated” Quasar MRK 231: Absorption and Emission From a High-Speed Dusty Nuclear Outflow

Veilleux

Meléndez

Tripp

et al. 2016

ApJ

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New near-and far-ultraviolet (NUV and FUV) Hubble Space Telescope spectra of Mrk231, the nearest quasar known, are combined with ground-based optical spectra to study the remarkable dichotomy between the FUV and NUV-optical spectral regions in this object. The FUV emission-line features are faint, broad, and highly blueshifted (up to ∼7000 km s −1 ), with no significant accompanying absorption. In contrast, the profiles of the NUV absorption features resemble those of the optical Na ID, He I, and Ca II H and K lines, exhibiting broad blueshifted troughs that overlap in velocity space with the FUV emission-line features and indicate a dusty, highdensity and patchy broad absorption line (BAL) screen covering ∼90% of the observed continuum source at a distance 2-20 pc. The FUV continuum emission does not show the presence of any obvious stellar features and is remarkably flat compared with the steeply declining NUV continuum. The NUV (FUV) features and continuum emission have not varied significantly over the past ∼22 (3) years and are unresolved on scales ∼40 (170) pc. These results favor an active galactic nucleus origin for the NUV-FUV line and continuum emission. The observed FUV line emission is produced in the outflowing BAL cloud system, while the Balmer lines arise primarily from the standard broad line region seen through the dusty BAL screen. Our data are inconsistent with the recently proposed binary black hole model. We argue instead that Mrk231 is the nearest example of weak-lined "winddominated" quasars with high Eddington ratios and geometrically thick ("slim") accretion disks; these quasars are likely more common in the early universe.

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Section: Physical Model-revisitedmentioning

confidence: 99%

The Complete Ultraviolet Spectrum of the Archetypal “Wind-Dominated” Quasar MRK 231: Absorption and Emission From a High-Speed Dusty Nuclear Outflow

Veilleux

Meléndez

Tripp

et al. 2016

ApJ

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“…4.2), the variability time scales summarized in Table 6 imply very compact emission regions, and hence very high intrinsic brightness temperatures. Following Marscher et al (1979), and taking an isotropically expanding light-sphere without preferred direction into account, the light travel time argument implies a diameter d ≤ 2 · cΔ t of the emitting region after the time interval Δt [s] of expansion. We then obtain for the diameter of the variable emission region θ [mas]:…”

Section: Variability Time Scales and Brightness Temperaturesmentioning

confidence: 99%

“…Consequently the SF/ACF methods deliver variability time scale of 3−4 days, which owing to the limited total observing time must formally be regarded as lower limits to the true variability time scale t var . In these cases we make use of the following definition of the time scale t var to obtain better estimates of the "true" variability time scales directly from those time series where only a several day trend was observed (see also Marscher et al 1979, and references therein): 5) where S denotes the mean flux density [Jy] and ΔS = S max − S min the flux density variation in the considered time interval Δt. We note that this time scale relies on a "visual" inspection of the variability curves, defining by human eye (or mathematically via differentiation) the minimum and maximum of the flux density and the corresponding time interval Δt between these two flux density levels.…”

Section: Appendix A: Statistical Variability Analysismentioning

confidence: 99%

Testing the inverse-Compton catastrophe scenario in the intra-day variable blazar S5 0716+71

Fuhrmann

Krichbaum²,

Witzel³

et al. 2008

A&A

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Aims. The BL Lac object S5 0716+71 was observed in a global multi-frequency campaign to search for rapid and correlated flux density variability and signatures of an inverse-Compton (IC) catastrophe during the states of extreme apparent brightness temperatures. Methods. The observing campaign involved simultaneous ground-based monitoring at radio to IR/optical wavelengths and was centered around a 500-ks pointing with the INTEGRAL satellite (November 10−17, 2003). Here, we present the combined analysis and results of the radio observations, covering the cm-to sub-mm bands. This facilitates a detailed study of the variability characteristics of an inter-to intra-day variable IDV source from cm-to the short mm-bands. We further aim to constrain the variability brightness temperatures (T B ) and Doppler factors (δ) comparing the radio-bands with the hard X-ray emission, as seen by INTEGRAL at 3−200 keV. Results. 0716+714 was in an exceptionally high state and different (slower) phase of short-term variability, when compared to the past, most likely due to a pronounced outburst shortly before the campaign. The flux density variability in the cm-to mm-bands is dominated by a ∼4 day time scale amplitude increase of up to ∼35%, systematically more pronounced towards shorter wavelengths. The cross-correlation analysis reveals systematic time-lags with the higher frequencies varying earlier, similar to canonical variability on longer time-scales. The increase of the variability amplitudes with frequency contradicts expectations from standard interstellar scintillation (ISS) and suggests a source-intrinsic origin for the observed inter-day variability. We find an inverted synchrotron spectrum peaking near 90 GHz, with the peak flux increasing during the first 4 days. The lower limits to T B derived from the inter-day variations exceed the 10 12 K IC-limit by up to 3−4 orders of magnitude. Assuming relativistic boosting, our different estimates of δ yield robust and self-consistent lower limits of δ ≥ 5−33 -in good agreement with δ VLBI obtained from VLBI studies and the IC-Doppler factors δ IC > 14−16 obtained from the INTEGRAL data. Conclusions. The non-detection of S5 0716+714 with INTEGRAL in this campaign excludes an excessively high X-ray flux associated with a simultaneous IC catastrophe. Since a strong contribution from ISS can be excluded, we conclude that relativistic Doppler boosting naturally explains the apparent violation of the theoretical limits. All derived Doppler factors are internally consistent, agree with the results from different observations and can be explained within the framework of standard synchrotron-self-Compton (SSC) jet models of AGN.

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“…For example, it was shown that the predicted X-ray flux density from SSC in a compact, spherical, variable radio source must be reduced by a factor of δ 2(3α+5) if variability is used to measure the size, and the observed self-absorption turn-over frequency is used to estimate the magnetic-field strength [85,86].…”

Section: Effects Of Bulk Relativistic Motionmentioning

confidence: 99%