Related papers: Modeling the Emission Processes in Blazars
Microquasars are sources of very high-energy gamma-rays and, very probably, high-energy gamma-ray emitters. We propose a model for a jet that can allow to give accurate observational predictions for jet emission at different energies and…
We propose and test a fairly simple idea that could account for the blazar sequence: all jets are launched with similar energy per baryon, independently of their power. For instance, flat-spectrum radio quasars (FSRQs), the most powerful…
Most models for blazars and gamma-ray bursts involve relativistic plasma outflows powered by accretion processes onto black holes. The blast wave physics developed for cosmological models of GRBs is reviewed. Two points relevant for blazar…
The blazar 3C 279 is well known for its rapid and large-amplitude variability. On 20 December 2013, the source exhibited an orphan {\gamma}-ray flare characterized by a flux-doubling timescale of a few hours, a very hard spectrum, a…
At TeV energies, the gamma-ray horizon of the universe is limited to redshifts z<<1, and, therefore, any observation of TeV radiation from a source located beyond z=1 would call for a revision of the standard paradigm. While robust…
Ultrahigh energy protons and nuclei from extragalactic cosmic ray sources initiate intergalactic electromagnetic cascades, resulting in observable fluxes of $\gamma$-rays in the GeV-TeV energy domain. The total spectrum of such cascade…
Intense outbursts in blazars are among the most extreme phenomena seen in extragalactic objects. Studying these events can offer important information about the energetic physical processes taking place within the innermost regions of…
Context: Being dominated by non-thermal emission from aligned relativistic jets, blazars allow us to elucidate the physics of extragalactic jets, and, ltimately, how the energy is extracted from the central black hole in radio-loud active…
Blazar spectral models generally have numerous unconstrained parameters, leading to ambiguous values for physical properties like Doppler factor delta or fluid magnetic field B'. To help remedy this problem, a few modifications of the…
Published EGRET spectra from blazars extend only to 10 GeV, yet EGRET has detected approximately 2000 gamma-rays above 10 GeV of which about half are at high Galactic latitude. We report a search of these high-energy gamma-rays for…
The flat spectrum radio quasar PKS 1222+216 was detected in the very high energy gamma-ray band by MAGIC during a highly active gamma-ray phase following an alert by the LAT onboard Fermi. Its relatively hard spectrum without a cut off,…
Blazars are among the most energetic and violent objects in the universe. By observing blazars at very high energies (VHE, E > 100 GeV) we can better understand blazar emission mechanisms, jet structure, black hole accretion and the…
Blazars are a small fraction of all extragalactic sources but, unlike other objects, they are strong emitters across the entire electromagnetic spectrum. In this study we have conducted a detailed investigation of the broad-band spectral…
Variable \gama-ray emission from blazars, one of the most powerful classes of astronomical sources featuring relativistic jets, is a widely discussed topic. In this work, we present the results of a variability study of a sample of 20…
A very bright and fast varying gamma-ray flare has been detected from the blazar 3C 279 on June 16, 2015. We have studied the broadband spectral energy distribution of the source during the flaring episode and in the low activity state…
Comprehensive VLBI and multi-waveband monitoring indicate that a single superluminal knot can cause a number of gamma-ray flares at different locations. However, the often very rapid variability timescale is a challenge to theoretical…
The KM3NeT collaboration has reported the detection of the highest energy neutrino event observed to date. The energy of the event is of the order of 220 PeV hinting towards a neutrino flux at the highest energies. In this article, the…
High-redshift ($z >3$) $\gamma$-ray blazars are rare, but they are crucial for our understanding of jet evolution, $\gamma$-ray production and propagation, and the growth of supermassive black holes in the early universe. A new analysis of…
High-redshift blazars are the most powerful extragalactic astrophysical sources ever detected in the high-energy gamma-ray band. In this study, we present a temporal and spectral analysis of the high-redshift blazar B3 1343+451 based on 14…
The discovery of strong gamma-ray and hard X-ray emission and the results from various multifrequency campaigns have disclosed new aspects of the blazar phenomenology, leading to a much more robust understanding of the mechanisms underlying…