Multiepoch Very Long Baseline Array Observations of EGRET-detected Quasars and BL Lacertae Objects: Connection between Superluminal Ejections and Gamma-Ray Flares in Blazars

By S. Jorstad, A. Marscher, J. Mattox, M. Aller, H. Aller, A. Wehrle, S. Bloom. 2001

164 citations recorded by the source corpus.

We examine the coincidence of times of high γ-ray flux and ejections of superluminal components from the core in EGRET blazars based on a Very Long Baseline Array (VLBA) monitoring program at 22 and 43 GHz from 1993 November to 1997 July. In 23 cases of γ-ray flares for which sufficient VLBA data exist, 10 of the flares (in eight objects) fall within 1 σ uncertainties of the extrapolated epoch of zero separation from the core of a superluminal radio component. In each of two sources (0528+134 and 1730-130), two successive γ-ray flares were followed by the appearance of new superluminal components. We carried out statistical simulations that show that if the number of coincidences is ≥10, the radio and γ-ray events are associated with each other at greater than 99.999% confidence. Our analysis of the observed behavior, including variability of the polarized radio flux, of the sources before, during, and after the γ-ray flares suggests that the γ-ray events occur in the superluminal radio knots. This implies that the γ-ray flares are caused by inverse Compton scattering by relativistic electrons in the parsec-scale regions of the jet rather than closer to the central engine.

Subfields: Astronomy and Astrophysics, Atmospheric Science, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/102b89bd9ec81ec537ad2e8130d7812f2675f63d

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Citations in the corpus

Detection of significant cm to sub-mm band radio and γ-ray correlated variability in Fermi bright blazars (2014, background): “…ejection/kinematics suggest relativistic shocks, shock-shock interaction and/or multiple jet regions on pc scales as sites of the γ-ray emission (e.g. Jorstad et al. 2001; Marscher et al. 2010; Jorstad et al. 2010; Agudo et al. 2011b; Schinzel et al. 2012; Rani et al. 2013; Orienti et al. 2013;…”
Superluminal Radio Features in the M87 Jet and the Site of Flaring TeV Gamma-Ray Emission (2007, background): “…detections of superluminal motions are now commonplace in more distant relativistic jet sources (e.g., Kellermann et al. 2004), the physical link to the higher-energy activity has not been possible previously because of the lack of comparably high spatial resolution (e.g., Jorstad et al. 2001).”
The Fermi blazars' divide (2009, background): “These inferences come from superluminal motion (Jorstad et al. 2001; Kellerman et al. 2004), direct modelling of their SED (e.g. Konopelko et al. 2003; Finke, Dermer & Böttcher 2008)and very rapid TeV variability (e.g. Begelman, Fabian & Rees 2008; Ghisellini & Tavecchio 2008b).”
BLAZARS IN THE FERMI ERA: THE OVRO 40 m TELESCOPE MONITORING PROGRAM (2010, background): “…GeV emission region are that this emission comes from a “gamma-sphere” close to the base of the jet (Blandford & Levinson 1995), or that it comes from the same shocked regions that are responsible for the radio emission seen in VLBI observations much further out in the jet (Jorstad et al. 2001).”
LOCATION OF γ-RAY FLARE EMISSION IN THE JET OF THE BL LACERTAE OBJECT OJ287 MORE THAN 14 pc FROM THE CENTRAL ENGINE (2010, unknown): “We identify C0 as such a feature, and C1 as a second re-collimation shock, as seen in hydrodynamical simulations (Gómez et al. 1997; Agudo et al. 2001) and often in VLBA images (Jorstad et al. 2001a, 2005).”
Correlated Multi-Wave Band Variability in the Blazar 3C 279 from 1996 to 2007 (2008, methodology): “For epochs from 1995 to 2001, we use the images and results of Lister et al. (1998),Wehrle et al. (2001), and Jorstad et al. (2001, 2005).”
PROBING THE INNER JET OF THE QUASAR PKS 1510−089 WITH MULTI-WAVEBAND MONITORING DURING STRONG GAMMA-RAY ACTIVITY (2010, result): “…after a very bright superluminal knot passed through the core (which coincided with the peak of a major X-ray flare), consistent with the finding of Jorstad et al. (2001) and Lähteenmäki & Valtaoja (2003) that high γ-ray states often follow the time when a new superluminal knot coincides with…”
CONSTRAINING EMISSION MODELS OF LUMINOUS BLAZAR SOURCES (2009, background): “In fact, a role of reconfinement shocks in shaping radiative and morphological properties of blazar jets has been discussed previously by several authors (Jorstad et al. 2001a, 2001b; Cheung et al. 2007; Sikora et al. 2008; Nalewajko & Sikora 2009; Bromberg & Levinson 2009).”
Relativistic Magnetohydrodynamics with Application to Gamma-Ray Burst Outflows. I. Theory and Semianalytic Trans-Alfvénic Solutions (2003, background): “…of pairs. γ-ray emission in the blazar class of AGNs originates in superluminal radio knots — which likely represent discrete blobsr shocks in a relativistic jet — at a large distance from the origin (e.g., Jorstad et al. 2001b).18 This is essentially the picture envisioned for GRB outflows.”
Kinematics of Parsec-scale Jets of Gamma-Ray Blazars at 43 GHz within the VLBA-BU-BLAZAR Program (2017, methodology): “Using multi-epoch images obtained with the Very Long Baseline Array (VLBA), Jorstad et al. (2001a) found a statistically significant correlation between the flux density of the compact “core” and the γ-ray flux in a sample of FSRQs and BLLacs detected by EGRET, while Jorstad et al. (2001b) reported…”
Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Jet Kinematics from Bimonthly Monitoring with the Very Long Baseline Array (2005, methodology): “For example, γ-ray blazars, which exhibit the highest apparent speeds (Jorstad et al. 2001a; Kellermann et al. 2004), do not possess more pronounced bends than sources not yet detected in γ-rays (Kellermann et al. 1998; Jorstad et al. 2001a).”