Cosmic Gamma Radiation

Inverse Compton Versus n0-Decay Gamma Rays (Cosmic Gamma Radiation)

When deriving information about the accelerated protons one has to subtract a possibly non-negligible "contamination" caused by directly accelerated electrons that upscatter photons of the 2.7 K CMBR (which is the dominant target photon field in most of SNRs) to Y-ray energies. The same multi-TeV electrons responsible for IC Y-rays of TeV energies produce also […]

Synchrotron X-ray Emission of SNRs (Cosmic Gamma Radiation)

The IC origin of TeV emission of SNRs implies the existence of multi-TeV electrons and, therefore, unavoidable synchrotron radiation extending to O/UV and shorter wavelengths. In the galactic plane the magnetic field is estimated to be as large asSince the the energy density of such magnetic fields exceeds the density of the 2.7 K CMBR […]

TeV Gamma Radiation of SN 1006 and Similar SNRs (Cosmic Gamma Radiation)

Inverse Compton models of TeV emission The featureless X-ray emission observed by ASCA from the shell of SN 1006 (Koyama et al., 1995) is naturally interpreted as synchrotron emission ofelectrons accelerated to energies ~ 100 TeV at the shock front. Motivated by this fact, several theorists (Mastichiadis, 1996; Mastichiadis and De Jager, 1996; Pohl, 1996; […]

Molecular Clouds Overtaken by SNRs (Cosmic Gamma Radiation)

The reasons which make the detection and identification ofrays from SNRs that are located in ordinary (low-density) regions of the ISM rather difficult, are twofold: (i) slow interaction rate allowing only limited efficiency of conversion of energy of relativistic protons to Y-rays,(ii) significant "contamination" due to the IC component of radiation, especially at TeV energies. […]

A Special Case: Gamma Rays from Cassiopeia A (Cosmic Gamma Radiation)

The shell type supernova remnant Cassiopeia A is the brightest and one of the best studied radio sources in our Galaxy. The synchrotron radiation of this source continues to submillimeter wavelengths, and perhaps even further to the infrared (Tuffs et al., 1997) and hard X-rays (Allen et al., 1997). The estimates of the mean magnetic […]

"PeV SNRs" (Cosmic Gamma Radiation)

The featureless energy spectrum of cosmic rays, extending as a single power-law up to the knee around 1015 eV, indicates that the flux of galactic CRs is dominated by a single source population. If so, the representatives of this source population should be sources of nonthermal synchrotron X-rays and very high energy Y-rays. Since both […]

Magnetospheric Gamma Rays (Cosmic Gamma Radiation)

Pulsars – rapidly rotating, magnetized neutron stars – were the first as-trophysical sources discovered in high energy Y-rays (for review see e.g. Fichtel and Trombka, 1997) In fact, these objects, with the Vela pulsar as the brightest persistent GeV source in the Y-ray sky, remain the only firmly identified Y-ray source population in our Galaxy. […]

Gamma Rays from Unshocked Pulsar Winds (Cosmic Gamma Radiation) Part 1

Rotation powered pulsars eject plasma in the form of relativistic winds that carry off most of the rotational energy of the pulsars. The best observed example is the pulsar in the Crab Nebula. This pulsar ejects a relativistic wind which is terminated at a distance of about 0.1 pc by a standing reverse shock. The […]

Gamma Rays from Unshocked Pulsar Winds (Cosmic Gamma Radiation) Part 2

Gamma rays from winds of PSR B1706-44 and Vela? The radio pulsar PSR B1706-44, which has a rotation period P = 102 ms, characteristic age T = 1.7 x 104 yr, and spin-down luminosity E = 3.4 x 1036 erg/s, is one of the six high energy Y-ray pulsars detected by EGRET (Thompson, 1999). The […]

Gamma Rays from Pulsar Driven Nebulae (Cosmic Gamma Radiation)

Pulsars lose their rotational energy by driving ultrarelativistic winds of electrons, positrons and, possibly, ions. If a pulsar is surrounded by a supernova remnant, its winds are thought to terminate at a collisionless shock front, the location of which is determined by the balance between the wind ram pressure and the total pressure in the […]

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