Internal shocks in the jets of radio-loud quasars

By M. Spada, G. Ghisellini, D. Lazzati, A. Celotti. 2001

294 citations recorded by the source corpus.

The central engine causing the production of jets in radio sources may work intermittently, accelerating shells of plasma with different mass, energy and velocity. Faster but later shells can then catch up slower earlier ones. In the resulting collisions shocks develop, converting some of the ordered bulk kinetic energy into magnetic field and random energy of the electrons which then radiate. We propose that this internal shock scenario, which is the scenario generally thought to explain the observed gamma-ray burst radiation, can also work for radio sources in general, and for blazars in particular. We investigate in detail this idea, simulating the birth, propagation and collision of shells, calculating the spectrum produced in each collision, and summing the locally produced spectra from those regions of the jet which are simultaneously active in the observer's frame. We can thus construct snapshots of the overall spectral energy distribution, time-dependent spectra and light curves. This allows us to characterize the predicted variability at any frequency, study correlations between the emission at different frequencies, specify the contribution of each region of the jet to the total emission, and find correlations between flares at high energies and the birth of superluminal radio knots and/or radio flares. The model has been applied to reproduce qualitatively the observed properties of 3C 279. Global agreement in terms of both spectra and temporal evolution is found. In a forthcoming work, we will explore the constraints that this scenario sets on the initial conditions of the plasma injected in the jet and the shock dissipation for different classes of blazars.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7409ede450b991d7dd5e78082573730334b4abb3

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Citations in the corpus

The power of blazar jets (2007, background): “An interpretation of such findings is po sible within the internal shock scenario (Ghisellini 1999; Spada et al. 2001; Guetta et al 2004), which could account for the radiative efficiency, location of the dissipative region and spectral trend if the particle acceleration process is balanced by the…”
A Unified Model for Black Hole X-Ray Binary Jets? (2004, background): “Internal shocks have previously been proposed for AGN (e.g. Rees 1978; Marscher & Gear 1985; Ghisellini 1999; Spada et al. 2001) and gamma-ray bursts (GRBs) (e.g. Rees & Meszaros 1994; van Paradijs, Kouveliotou & Wijers 2000 and references therein).”
Synchrotron Self-Compton Model for Rapid Nonthermal Flares in Blazars with Frequency-dependent Time Lags (2004, methodology): “Furthermore, our formalism can be applied to the Spada et al. (2001) scenario with a suitable Lorentz transformation.”
The role of kink instability in Poynting-flux dominated jets (2006, background): “…reason to assume Poynting-flux dominated jets on scales larger than a few pc and that the observed emission on these scales can be understood as energy dissipated in shocks internally in the flow (Sikora et al. 1994; Spada et al. 2001) or due to interaction of the flow with the external medium.”
Photopolarimetric Monitoring of Blazars in the Optical and Near-Infrared Bands with the Kanata Telescope. I. Correlations between Flux, Color, and Polarization (2011, background): “The most plausible scenario for the origin of the energy injection is internal shocks in relativistic shells (e.g. Spada et al. 2001; Zhang et al. 2002).”
An Accretion-Jet Model for Black Hole Binaries: Interpreting the Spectral and Timing Features of XTE J1118+480 (2004, methodology): “In the present paper, following Spada et al. (2001), we adopt the internal shock scenario widely used in interpreting gamma-ray burst (GRB) afterglows (e.g., Piran 1999).”
The blazar sequence: a new perspective (2008, background): “…is appropriate both in the case of an accelerating jet and in the scenario of internal shocks (Sikora, Begelman & Rees 1994; Ghisellini 1999; Spada et al. 2001) where we have Rdiss ∼ 2 R0 ∼ a( )Rs, (9) where R0 is the initial separation of two consecutive shells, which can be approximated…”
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.”
CONSTRAINING EMISSION MODELS OF LUMINOUS BLAZAR SOURCES (2009, background): “In addition, in the internal shock model (Spada et al. 2001), the presence of cold jet electrons should manifest itself as soft and hard X-ray precursors of non-thermal blazar flares (Moderski et al. 2004).”
Are Quasar Jets Dominated by Poynting Flux? (2005, background): “The internal shocks have been proposed to result from collisions between velocity inhomogeneities propagating down a matter-dominated jet (Sikora et al. 1994; Spada et al. 2001).”
GRS 1915+105 and the Disc-Jet Coupling in Accreting Black Hole Systems (2004, methodology): “The internal-shock model based on varying flow speeds in a semicontinuous jet was originally developed for the jets of the AGN M87 (Rees 1978), and later considered for gamma-ray bursts (Rees & Meszaros 1994) and generically for radio-loud quasars (Spada et al. 2001).”
GAMMA-RAY LIGHT CURVES AND VARIABILITY OF BRIGHT FERMI-DETECTED BLAZARS (2010, background): “Large flares likely arise from the sudden acceleration of relativistic electrons, related to bulk injections of new particles and/or strong internal shocks (Mastichiadis & Kirk 1997; Spada et al. 2001; Böttcher & Dermer 2010).”
X-Ray Emission from Extragalactic Jets (2006, background): “Modulations of the power output are believed to cause the large amplitude brightness variations of the (unresolved) X-ray and γ-ray emission from blazars (Spada et al. 2001, Tanihata et al. 2003).”
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).”
A Multiwavelength View of the TeV Blazar Markarian 421: Correlated Variability, Flaring, and Spectral Evolution (2005, background): “Blazar flares are thought to be related to internal shocks in the jet (Rees 1978; Spada et al. 2001), or to the ejection of relativistic plasma into the jet (e.g., Böttcher et al. 1997; Mastichiadis & Kirk 1997).”
The Jet-Disk Connection and Blazar Unification (2002, background): “It is interesting to note that similar values are naturally predicted by the internal shock scenario, recently proposed for blazars by Spada et al. (2001).”