We present ASCA results on four prototype powerful far-infrared galaxies, Mrk231, Mrk273, Arp220 and NGC6240. The soft X-ray spectra show signatures of thermal emission with temperatures of (0.5–1)×10 K, which is probably produced in starbursts. Their soft X-ray (0.5–2 keV) luminosities range from 4×10erg s−1 to 7×10erg s−1. The X-ray properties are examined in the context of a starburst. Evide...

We investigate radio and X-ray imaging data for two solar ares in order to test the idea that asymmetric precipitation of nonthermal electrons at the two ends of a magnetic loop is consistent with the magnetic mirroring explanation. The events we present were observed in May 1993 by the HXT and SXT X-ray telescopes on the Yohkoh spacecraft, and by the Nobeyama 17 GHz radioheliograph. The hard X...

The general properties of the non-thermal non-pulsed X-ray emission of rotation powered pulsars are investigated in the context of a pulsar wind nebula model. An examination of the observed X-ray emission from a sample of 23 pulsars in the energy range between 2-10 keV reveals that the relation of X-ray luminosity, Lx, to the pulsar spin down power, Ė, is steeper for the non-pulsed component th...

We present the X-ray properties of a sample of 17 radio sources observed with the Chandra X-ray Observatory as part of a project aimed at studying the X-ray emission from their radio jets. In this paper, we concentrate on the X-ray properties of the unresolved cores. The sample includes 16 quasars (11 core-dominated and 5 lobe-dominated) in the redshift range z=0.30–1.96, and one low-power radi...

We report results from a systematic study of the spectral energy distribution (SED) and spectral evolution of XTE J1550–564 and H 1743–322 in outburst. The jets of both sources have been directly imaged at both radio and X-ray frequencies, which makes it possible to constrain the spectrum of the radiating electrons in the jets. We modelled the observed SEDs of the jet ‘blobs’ with synchrotron e...

Clusters of galaxies have not yet been detected at gamma-ray frequencies; however, the recently launched Fermi Gamma-ray Space Telescope, formerly known as GLAST, could provide the first detections in the near future. Clusters are expected to emit gamma rays as a result of (1) a population of high-energy primary and re-accelerated secondary cosmic rays fueled by structure formation and merger s...

We correlate the ROSAT 4 keV all-sky survey with the Leiden/Dwingeloo H i survey, looking for soft X-ray signatures of prominent high-velocity-cloud (HVC) complexes. We study the transfer of 4 keV photons through the interstellar medium in order to distinguish variations in the soft X-ray background (SXRB) intensity caused by photoelectric absorption effects from those due to excess X-ray emiss...

Constraints on the dynamics, dissipation, and production of VHE neutrinos in relativistic jets are derived using opacity calculations and VHE γ-ray observations. In particular, it is demonstrated how rapid variability of the γ-ray emission at very high energies (> 100 GeV) can be used to map the location of the γ-spheres, to derive lower limits on the Doppler factor of the γ-ray emission zone, ...