相关论文: PKS 1622-253: A Weakly Accreting, Powerful Gamma R…
We present our latest results on the connection between accretion rate and relativistic jet power in AGN, by using a large sample which includes mostly blazars, but contains also some radio--galaxies. The jet power can be traced by…
The Italian gamma-ray satellite AGILE has recently reported the detection of some variable high-energy sources likely of galactic origin. These sources do not have any obvious counterpart at lower energies. We propose that these sources are…
PKS 1510-089 (z=0.361) is one of only a handful of flat spectrum radio quasars that have been detected at very high energy (VHE, $E>100\,$GeV) gamma rays. It is a very active source across the entire electromagnetic spectrum. VHE…
We present the results from a multiwavelength campaign of the powerful Gamma-ray quasar PKS 1510-089. This campaign commenced with a deep Suzaku observation lasting three days for a total exposure time of 120 ks, and continued with Swift…
Advances in the capabilities of X-ray, gamma-ray and TeV telescopes have brought new information on the physics of relativistic jets, which are responsible for the blazar "phenomenon". In particular the broad band sensitivity of the…
Gamma Ray Bursts (GRB) are the extremely energetic transient events, visible from the most distant parts of the Universe. They are most likely powered by accretion on the hyper-Eddington rates that proceeds onto a newly born stellar mass…
Extragalactic relativistic jets are engines able to carry out to large distances a huge amount of power, not only in the form of radiation, but especially in the form of kinetic energy of matter and fields. As such, they can be thought as…
Among unidentified gamma-ray sources in the galactic plane, there are some that present significant variability and have been proposed to be high-mass microquasars. To deepen the study of the possible association between variable low…
We present XMM-Newton imaging spectroscopy of ten weak emission-line quasars (WLQs) at $0.928\leq z \leq 3.767$, six of which are radio quiet and four which are radio intermediate. The new X-ray data enabled us to measure the power-law…
Compton scattering of external radiation by nonthermal particles in outflowing blazar jets is dominated by accretion-disk photons rather than scattered radiation to distances $\sim 0.01-0.1$ pc from the central engine for standard…
Microquasars are X-ray binary systems with non-thermal radio emission originated in jet-like features. They are attractive sites for gamma-ray production, since relativistic particles in the jet should traverse locally strong both photon…
Based on broadband spectral energy distribution (SEDs), we estimate the jet physical parameters of 1392 $\gamma$-ray-loud active galactic nuclei (AGNs), the largest sample so far. The (SED) jet power and magnetization parameter are derived…
The study of relativistic particle acceleration is a major topic of high-energy astrophysics. It is well known that massive black holes in active galaxies can release a substantial fraction of their accretion power into energetic particles,…
We present the results from the Suzaku X-ray observations of five flat-spectrum radio quasars (FSRQs), namely PKS0208-512, Q0827+243, PKS1127-145, PKS1510-089 and 3C 454.3. All these sources were additionally monitored simultaneously or…
The detection of several radio-loud narrow-line Seyfert 1 (NLS1) galaxies by the Fermi Gamma-Ray Space Telescope hints at the existence of a rare, new class of gamma-ray emitting active galactic nuclei with low black hole masses. Like flat…
PKS 1510-089 is a powerful Flat Spectrum Radio Quasar at z=0.361 with radiative output dominated by the gamma-ray emission. In the last two years PKS 1510-089 showed high variability over all the electromagnetic spectrum and in particular…
The power carried by the jet of blazars is large, compared to the luminosity produced by their accretion disk, and is probably in the form of kinetic energy of a normal electron-proton plasma. The Poynting flux is modest, as suggested by…
The connection between the accretion process that powers AGN and the formation of jets is still poorly understood. Here we tackle this issue using new, deep \chandra and \xmm observations of the cores of three powerful radio loud quasars:…
A subset of the unidentified EGRET gamma-ray sources with no active galactic nucleus or other conspicuous counterpart appears to be concentrated at medium latitudes. Their long-term variability and their spatial distribution indicate that…
The physical origin of the X-ray emission in powerful quasar jets has been a long-standing mystery. Though these jets start out on the sub-pc scale as highly relativistic flows, we do not have any direct measurement of their speeds on the…