Synchrotron Self-Compton Model for Rapid Nonthermal Flares in Blazars with Frequency-dependent Time Lags

By A. Sokolov, A. Marscher, I. McHardy. 2004

147 citations recorded by the source corpus.

We model rapid variability of multifrequency emission from blazars occurring across the electromagnetic spectrum (from radio to gamma rays). Lower energy emission is produced by the synchrotron mechanism, whereas higher energy emission is due to inverse Compton scattering of the synchrotron emission. We take into account energy stratification established by particle acceleration at shock fronts and energy losses due to synchrotron emission. We also consider the effect of light-travel delays for the synchrotron emission that supplies the seed photons for inverse Compton scattering. The production of a flare is caused by the collision between a relativistic shock wave and a stationary feature in the jet (e.g., a Mach disk). The collision leads to the formation of forward and reverse shocks, which confine two contiguous emission regions resulting in complex profiles of simulated flares. Simulations of multifrequency flares indicate that relative delays between the inverse Compton flares and their synchrotron counterparts are dominated by energy stratification and geometry of the emitting regions, resulting in both negative and positive time delays depending on the frequency of observation. Light-travel effects of the seed photons may lead to a noticeable delay of the inverse Compton emission with respect to synchrotron variability if the line of sight is almost perfectly aligned with the jet. We apply the model to a flare in 3C 273 and derive the properties of shocked plasma responsible for the flare. We show that the pronounced negative time delay between the X-ray and IR light curves (X-rays peak after the maximum in the synchrotron emission) can be accounted for if both forward and reverse shocks are considered.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/c1b311aa46d958047cde0783171e93a3597a4948

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In Astronomy and Astrophysics

1. A. Marscher
2. E. Orlando
3. B. Cerutti
4. A. Reimer
5. M. Böttcher
6. A. Prakash
7. K. Sweeney
8. S. Jorstad

In Nuclear and High Energy Physics

1. A. Marscher
2. E. Orlando
3. B. Cerutti
4. I. Grenier
5. A. Reimer
6. C. Dermer
7. M. Böttcher
8. A. Prakash

Citations in the corpus

• LEPTONIC AND HADRONIC MODELING OF FERMI-DETECTED BLAZARS (2013, background): “…the spine-sheath model of Tavecchio & Ghisellini (2008) or the decelerating jet model of Georganopoulos & Kazanas (2003), as well as internal shock models (e.g., Marscher & Gear 1985; Spada et al. 2001; Sokolov et al. 2004; Graff et al. 2008; Joshi & Böttcher 2011; Böttcher & Dermer 2010).”
• Correlated Multi-Wave Band Variability in the Blazar 3C 279 from 1996 to 2007 (2008, methodology): “According to Sokolov et al. (2004) if the emission region is thicker (thickness comparable to the radius), the allowed angle increases to 2 0:4 .”
• GAMMA-RAY LIGHT CURVES AND VARIABILITY OF BRIGHT FERMI-DETECTED BLAZARS (2010, background): “Flares observed at or above the peak energy reflect the scale of the source along the line of sight and are symmetric in the cylindrical geometry of the active regions (Eldar & Levinson 2000; Sokolov et al. 2004).”
• Non-thermal particle acceleration in collisionless relativistic electron-proton reconnection (2016, background): “…inferred in these systems have often been attributed to first-order Fermi MNRAS 000, 1–30 (0000) Relativistic electron-ion reconnection 25 acceleration in strong shocks (Spada et al. 2001; Sokolov et al. 2004), but such a model is viable only if the plasma involved is weakly magnetized.”