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Context. The LOFAR (LOw Frequency ARray) radio telescope is a giant digital phased array interferometer with multiple antennas distributed in Europe. It provides discrete sets of Fourier components of the sky brightness. Recovering the original brightness distribution with aperture synthesis forms an inverse problem that can be solved by various(More)
We report on simultaneous radio and X-ray observations of the black hole candidate XTE J1650−500 during the course of its 2001-2002 outburst. The scheduling of the observations allowed us to sample the properties of XTE J1650−500 in different X-ray spectral states, namely the hard state, the steep power-law state and the thermal dominant state, according to(More)
The daily monitoring observations of black hole transients with RXTE provided important clues on the conditions of the state transitions, both in terms of spectra and timing. The recent addition of monitoring in the optical-infrared and the radio band significantly extended our knowledge of the relation between the jets and the spectral states. However,(More)
We report results of Chandra X-ray and VLA radio observations of the Galactic accreting black hole V404 Cyg (GS 2023+338) in its quiescent state. V404 Cyg is detected at its faintest level of radio and X-ray emission with a 0.5–10 keV unabsorbed luminosity of 8.3 × 10 (d/3.5 kpc) erg s. The X-ray spectrum fit with an absorbed power-law model yields a photon(More)
We have detected, at x-ray and radio wavelengths, large-scale moving jets from the microquasar XTE J1550-564. Plasma ejected from near the black hole traveled at relativistic velocities for at least 4 years. We present direct evidence for gradual deceleration in a relativistic jet. The broadband spectrum of the jets is consistent with synchrotron emission(More)
We report the results of a long-term campaign of radio, softand hardX-ray observations of the galactic black hole candidate GX 339–4. In the Low-Hard X-ray state the system displays a strong 3-way linear correlation between softand hard-X-rays and radio emission, implying a coupling between the Comptonising corona and a radio-emitting compact jet. In this(More)
INTEGRAL regularly scans the Galactic plane to search for new objects and in particular for absorbed sources with the bulk of their emission above 10 − 20 keV. The first new INTEGRAL source was discovered on 2003 January 29, 0.5 from the Galactic plane and was further observed in the X-rays with XMM-Newton. This source, IGR J16318−4848, is intrinsically(More)
Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here, we report the Fermi Large Area Telescope detection of variable gamma-ray(More)
We report on the formation and evolution of a large-scale, synchrotron-emitting jet from the black hole candidate and X-ray binary system GX 339−4. In 2002 May, the source moved from a low/hard to a very high X-ray state, contemporaneously exhibiting a very bright optically thin radio flare. Further observations with the Australia Telescope Compact Array(More)