Related papers: XRF 050406 late-time flattening: an inverse Compto…

The extended high-energy gamma-ray (>100 MeV) emission occurred after the prompt gamma-ray bursts (GRBs) is usually characterized by a single power-law spectrum, which has been explained as the afterglow synchrotron radiation. The afterglow…

GRB 000926 has one of the best-studied afterglows to-date, with multiple X-ray observations, as well as extensive multi-frequency optical and radio coverage. Broadband afterglow observations, spanning from X-ray to radio frequencies,…

We investigate two high energy radiation mechanisms, the proton synchrotron and the electron inverse Compton emission, and explore their possible signatures in the broad-band spectra and in the keV to GeV light curves of gamma-ray burst…

We report the discovery of an X-ray counterpart to the southern radio hotspot of the largest-known radio quasar 4C 74.26 (whose redshift is z=0.104). Both XMM-Newton and Chandra images reveal the same significant (10arcsec, i.e. 19kpc)…

Observed in a significant fraction of clusters and groups of galaxies, diffuse radio synchrotron emission reveals the presence of relativistic electrons and magnetic fields permeating large-scale systems of galaxies. Although these…

Inhomogeneities in a synchrotron source can severely affect the conclusions drawn from observations regarding the source properties. However, their presence is not always easy to establish, since several other effects can give rise to…

We present observations of XRF 050406, the first burst detected by Swift showing a flare in its X-ray light curve. During this flare, which peaks at t_peak ~210s after the BAT trigger, a flux variation of (delta F)/F~6 in a very short time…

Cosmological fireball models of gamma-ray bursts (GRBs) predict delayed emission, ``after-glow,'' at longer wavelengths. We present several new results regarding the model predictions, and show that X-ray to optical observations of…

The Galactic fast radio burst (FRB) FRB 200428 was associated with a short X-ray burst (XRB) from the magnetar SGR J1935+2154 during one of its active phases. This FRB-associated XRB exhibits distinct properties compared to other typical…

I describe the modifications to the standard forward-shock model required to account for the X-ray light-curve features discovered by Swift in the early afterglow emission and propose that a delayed, pair-enriched, and highly relativistic…

We calculate the very high energy (sub-GeV to TeV) inverse Compton emission of GRB afterglows. We argue that this emission provides a powerful test of the currently accepted afterglow model. We focus on two processes: synchrotron…

We investigate whether the high energy tail detected by the Fermi/LAT for the short GRB 081024B can be caused by synchrotron and self-Compton emission in the context of either the internal or external shock models. For the internal shock…

High energy emission (> tens MeV) of Gamma-Ray Bursts (GRBs) provides an important clue to understand the physical processes involved in GRBs, which may be correlated with the GRB early afterglow. A shallow decline phase has been well…

In the framework of the quasar-radio galaxies unification the radio emitting lobes of FRII radio galaxies are pervaded by an intense quasar radiation field.Inverse Compton (IC) scattering between the relativistic electrons and the…

Swift discovered XRF 050416A with the BAT and began observing it with its narrow field instruments only 64.5 s after the burst onset. Its very soft spectrum classifies this event as an X-ray flash. The afterglow X-ray emission was monitored…

At the end of March 2004, the blazar S5 0716+714 underwent an optical outburst that prompted for quasi-simultaneous target-of-opportunity observations with the INTEGRAL and XMM-Newton satellites. In this paper, we report the results of the…

We present multi-wavelength observations of a typical long duration GRB 120326A at $z=1.798$, including rapid observations using a submillimeter array (SMA), and a comprehensive monitoring in X-ray and optical. The SMA observation provided…

The afterglow emission from gamma-ray bursts (GRBs) is believed to originate from a relativistic blast wave driven into the circumburst medium. Although the afterglow emission from radio up to X-ray frequencies is thought to originate from…

We report on the temporal and spectral characteristics of the early X-ray emission from the GRB 050822 as observed by Swift. This burst is likely to be an XRF showing major X-ray flares in its XRT light-curve. The quality of the data allows…

The origin of the shallow-decay emission during early X-ray afterglows has been an open issue since the launch of the Swift satellite. One of the appealing models is the late internal dissipation model, where X-ray emission during the…