Related papers: RXTE Observations of A2256
Wide-band Suzaku data on the merging cluster Abell 3667 were examined for hard X-ray emission in excess to the known thermal component. Suzaku detected X-ray signals in the wide energy band from 0.5 to 40 keV. The hard X-ray (> 10 keV) flux…
We present the first deep low frequency radio observations of the massive and highly disturbed galaxy cluster Abell 2744 using the upgraded Giant Metrewave Radio Telescope (uGMRT). The cluster is experiencing a very complex multiple merger…
Radio halos are elusive sources located at the center of merging galaxy clusters. To date, only about 40 radio halos are known, thus the discovery of new halos provide important insights on this class of sources. To improve the statistics…
Many galaxy clusters have giant halos of non-thermal radio emission, indicating the presence of relativistic electrons in the clusters. Relativistic protons may also be accelerated by merger and/or accretion shocks in galaxy clusters. These…
Relativistic electrons, seen in the large diffuse radio halo of the Coma cluster of galaxies, should scatter background photons to higher energies. We calculate the inverse Compton contributions from the microwave background, from the local…
In order to construct accurate point sources simulations at the frequencies relevant to 21 cm experiments, the angular correlation of radio sources must be taken into account. Using the 74 MHz VLSS survey, we measured the angular 2-point…
We report the discovery of variable circularly polarised radio emission associated with relativistic ejections from GRS 1915+105, based on observations with the Australia Telescope Compact Array (ATCA) and the Multi-Element Radio-Linked…
Using the X-ray data from \ASCA, spectral and spatial properties of the intra-cluster medium (ICM) of the cD cluster Abell 1795 are studied, up to a radial distance of $\sim 12'$ ($\sim 1.3$ $h_{50}^{-1}$ kpc). The ICM temperature and…
The wide-band energy spectrum of NGC6240 over the range 0.5-200keV is investigated using the RXTE and ASCA data. The RXTE data provide the spectrum beyond the ASCA range (0.5-10 keV) with significant detection of signals up to 20keV and the…
We present a detailed dynamical analysis of the rich galaxy cluster A2744, containing a powerful diffuse radio halo.Our analysis is based on redshift data for 102 galaxies, part of them recovered from unexplored spectra in the ESO archive.…
Radio relics are sites of electron (re)acceleration in merging galaxy clusters but the mechanism of acceleration and the topology of the magnetic field in and near relics are yet to be understood. We are carrying out an observational…
We report on new VLA radio observations performed at 1.4 GHz and 4.8 GHz with unprecedented sensitivity and angular resolution (~1 arcsec) of the cool core cluster A 2626, which is known to possess a radio mini-halo at its center. The most…
We discuss a series of observations of the black hole candidate GX 339-4 in low luminosity, spectrally hard states. We present spectral analysis of three separate archival Advanced Satellite for Cosmology and Astrophysics (ASCA) data sets…
The results from an X-ray spectral analysis of a large sample of quasars, observed with ASCA, are presented. Data reduction leaves 62 quasars, 35 radio-loud and 27 radio-quiet, suitable for spectral analysis. Differences are found between…
We present a radio and X-ray study of PKS 1353-341, the brightest cluster galaxy radio source at the center of a recent Chandra-discovered X-ray cluster. Our multi-frequency VLA images reveal an edge-brightened (FR-II), double-lobed…
New images of 7 radio halos and relics, obtained with the Very Large Array at 20 or 90 cm, are presented here. The existence of a cluster-wide radio halo in the clusters A 665 and CL 0016+16 is confirmed. Both these clusters share the…
Double radio relics in galaxy clusters are rare phenomena that trace shocks in the outskirts of merging galaxy clusters. We have carried out a spectral and polarization study of the spectacular double relics in the galaxy cluster A3376…
The goal of this work is to constrain the strength and structure of the magnetic field in the nearby cluster of galaxies A2255. At radio wavelengths A2255 is characterized by the presence of a polarized radio halo at the cluster center, a…
Using the HEXTE experiment on-board the RXTE satellite, we performed a search for hard X-ray tails in Sco X-1 spectra. We found strong evidence for the presence of such a non-thermal component on several occasions. Using the PCA/RXTE we…
We present new X-ray (Chandra) and radio (ATCA) observations of the z=0.09 radio galaxy PKS B1416-493, a member of the southern equivalent of the 3CRR sample. We find the source to be embedded in a previously unrecognized bright kT=4.6 keV…