Cosmic Gamma Radiation

High Energy Gamma Rays from Other Plerions (Cosmic Gamma Radiation)

The existence of the bright synchrotron nebula around the Crab pulsar very often is interpreted as a crucial condition for effective production of IC Y-rays. In fact, the strong magnetic field in the Crab Nebula produced by the strong wind only reduces the Y-ray production efficiency. Indeed, the energy density of the B-field exceeds by […]

Do We Expect Gamma Rays from X-Ray Binaries? (Cosmic Gamma Radiation)

In one of the first attempts to classify the potential VHE Y-ray emitters, X-ray binaries were attributed to the category of serendipitous sources, i.e. objects which "…do not have any firm a priori basis for their selection as candidate VHE Y-ray sources" (Weekes, 1992). Nevertheless, this very class of objects played an important role in […]

Nonthermal Phenomena in Microquasars (Cosmic Gamma Radiation)

The discovery of microquasars opened new possibilities for exploration of the phenomenon of relativistic jets common on a larger scale in AGN.Both type of objects are believed to be powered by accretion of matter by a collapsed object, by a stellar mass (typically 10 M0) black hole in a microquasar and by a super-massive (up […]

Modelling of Radio Flares of GRS 1915+105 (Cosmic Gamma Radiation)

Radio flares in microquasars are associated with ejection of pairs of rel-ativistic outflows which contain relativistic electrons and magnetic fields. Study of the 19 March 1994 outburst of GRS 1915+105, when such a pair of relativistic (v « 0.92c) radio jets were first discovered in a galactic source (Mirabel and Rodriguez, 1994), is still of […]

Expected Gamma Ray Fluxes (Cosmic Gamma Radiation)

The observations of synchrotron emission in the near IR band (e.g. Mirabel et al., 1998), and especially the detection of an IR synchrotron jet in GRS 1915+105 a few weeks after ejection (Sams et al., 1996; Eikenberry and Fazio, 1997), when the magnetic field in the expanding cloud hardly exceed 0.1 G, tell us that […]

Searching for Gamma Ray Signals from Microquasars (Cosmic Gamma Radiation)

The results of the previous section show that for flares as strong as the March 1994 outburst of GRS 1915+105, there are reasonably high expectations for detection of Y-ray signals from microquasars. The predicted fluxes are rapidly declining with the flare evolution, and depend strongly on the level of magnetic field in the ejecta as […]

The Case of Microblazars (Cosmic Gamma Radiation)

A characteristic feature of the two superluminal microquasars, GRS 1915+105 and GRO J1655-40, from which both the approaching and the receding jet components have been detected, is that the jets propagate at a very large angle to the observer,(Mirabel and Rodriguez, 1999). As a result, given that the Lorentz factors Tj of both these components […]

Ultraluminous Sources as Microblazars? (Cosmic Gamma Radiation)

X-ray studies based on the archival data obtained by the Einstein, ROSAT and ASCA satellites, as well as recent Chandra observations have revealed a new class of variable, and therefore compact, X-ray sources in nearby galaxies with luminosities in the range of 1039 — 1040 erg/s (e.g. Colbert and Mushotzky, 1999; Makishima et al., 2000) […]

Persistent Gamma Ray Emission from Extended Lobes (Cosmic Gamma Radiation)

Besides the Y-rays produced in small-scale (sub-parsec) jets of microquasars within the synchrotron-self-Compton (SSC) scenario, one may expect high energy radiation from the extended synchrotron lobes produced by the rel-ativistic electrons accelerated at the interface between the relativistic jets and the interstellar medium, similar to the scenario suggested for the extra-galactic FRII radio sources. This […]

Synchrotron and IC Models of Large Scale AGN Jets (Cosmic Gamma Radiation)

In this and the following topics we discuss properties of high energy non-thermal radiation observed or expected from the largest structures in the Universe – the so-called large-scale AGN jets and clusters of galaxies. There is an apparent link between these two source populations. The clusters of galaxies contain many AGN with powerful jets which […]

← Previous Entries

Next Entries →