相关论文: Internal shocks in blazar jets
The radio light curve and spectral evolution of the blazar CTA 102 during its 2006 outburst can be rather well explained by the standard shock-in-jet model. The results of a pixel-to-pixel spectral analysis of multi-frequency VLBI images,…
We review the observational differences between gamma-ray bursts occurring on a single shell (such as in the external shock model) and multiple shells (such as in the internal shock model). We do not argue against external shocks or for…
Blazar jets are renowned for their rapid violent variability and multiwavelength flares, however, the physical processes responsible for these flares are not well understood. In this paper we develop a time-dependent inhomogeneous fluid jet…
In the standard internal shock model, the observed X and gamma-ray radiation is assumed to be produced by synchrotron emission. I will show that there are serious problems with this interpretation, calling for other radiation mechanisms,…
We describe the time-dependent radiation transfer in blazar jets, within the internal shock model. We assume that the central engine, which consists of a black hole and an accretion disk, spews out relativistic shells of plasma with…
We investigate the dependence of gamma-ray brightness of blazars on intrinsic properties of their parsec-scale radio jets and the implication for relativistic beaming. By combining apparent jet speeds derived from high-resolution VLBA…
We investigate, independently of specific emission models, the constraints on the value of the bulk Lorentz factor Gamma of a fireball. We assume that the burst emission comes from internal shocks in a region transparent to Thomson…
We present an internal shock model with external characteristics for explaining the complicated light curves of gamma-ray bursts. Shocks produce gamma-rays in the interaction between a precessing beam of relativistic particles and the…
The innermost parts of powerful jets in active galactic nuclei are surrounded by dense, high-velocity clouds from the broad-line region, which may penetrate into the jet and lead to the formation of a strong shock. Such jet-cloud…
The principal paradigm for gamma-ray bursts suggest that the prompt transient gamma-ray signal arises from multiple shocks internal to the relativistic expansion. This paper illustrates some properties of diffusive acceleration at…
Our recent progress on time-dependent modeling of the multiwavelength spectra and variability of blazars with leptonic and hadronic jet models is reviewed. Special emphasis is placed on X-ray spectral variability of low-frequency peaked…
The highest-energy blazars exhibit non-thermal radiation extending beyond 1 TeV with high luminosities and strong variabilities, indicating extreme particle acceleration in their relativistic jets. The gamma-ray spectra of blazars contain…
In recent years, blazar surveys at radio and X-ray energies have greatly increased our understanding of this type of active galaxy. The combination of multi-wavelength data has shown that blazars follow a well defined sequence in terms of…
In our review of the blazar phenomenon, we discuss blazar models, with a focus on the following issues: sub-parsec jets and their environment; energy dissipation and particle acceleration; and radiative processes.
In the 1990s a comparison of sparse EGRET measurements with single-dish flux density monitoring from the Metsahovi and UMRAO programs established a temporal connection between the onset of flaring at radio band and the occurrence of…
Blazars show variability on timescales ranging from minutes to years, the former being comparable to and in some cases even shorter than the light-crossing time of the central black hole. The observed gamma-ray lightcurves can be described…
Since mid-2007 we have carried out a dedicated long-term monitoring programme at 15 GHz using the Owens Valley Radio Observatory 40 meter telescope. One of the main goals of this programme is to study the relation between the radio and…
The observed spectra of blazars, their intrinsic emission, and the underlying populations of radiating particles are intimately related. The use of these sources as probes of the extragalactic infrared background, a prospect propelled by…
We present the theoretical background and detailed equations for the synchrotron emission of a shock wave propagating in a relativistic jet. We then show how the evolution of an outburst in this shock-in-jet scenario can be analytically…
Relativistic jets from accreting supermassive black holes at cosmological distances can be powerful emitters of $\gamma$-rays. However, the precise mechanisms and locations responsible for the dissipation of energy within these jets,…