We present the results of a detailed correlation study between the soft X-ray, hard X-ray, and radio emission (obtained from RXTE ASM , BATSE, and GBI observations, respectively) of the bright radio emitting Galactic X-ray binary Cygnus X-3. We detect a very strong positive correlation between the soft X-ray and radio emission during the low-hard and minor flaring periods of the source, and an ...

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 index of 2.17 ± 0.13. Contrary to pre...

We present that the radio emission with flat spectrum in X-ray binaries comes from the synchrotron emission of relativistic electrons in the high energy tail of hot electrons in continuous conical jet. The jet is assumed to be produced by the advection-dominated accretion flow (ADAF) and maintains ion and electron temperatures constant in the case of adiabatic steady conical expansion. The flat...

DA 530 (G93.3+6.9) is a high Galactic latitude supernova remnant with a well-defined shell-like radio morphology and an exceptionally low X-ray to radio luminosity ratio. Based on a Chandra ACIS observation, we report the detection of an extended X-ray feature close to the center of the remnant with 5.3σ above the background within a circle of 20 radius. The spectrum of this feature can be char...

We have analyzed observations with the Chandra X-ray Observatory of the diffuse emission by hot gas in 7 dwarf starburst galaxies, 6 edge-on starburst galaxies, and 9 Ultra Luminous Infrared Galaxies. These systems cover ranges of ∼ 10 4 in X-ray luminosity and several thousand in star formation rate and K-band luminosity (a proxy for stellar mass). Despite this range in fundamental parameters,...

DA 530 (G93.3+6.9) is a high Galactic latitude supernova remnant with a well-defined shell-like radio morphology and an exceptionally low X-ray to radio luminosity ratio. Based on a Chandra ACIS observation, we report the detection of an extended X-ray feature close to the center of the remnant with 5.3σ above the background within a circle of 20 radius. The spectrum of this feature can be char...

The preliminary detection of the Galactic Center black hole Sgr A* in X-rays by the Chandra mission , as well as recent mm-VLBI measurements, impose strict constraints on this source. Using a relativistic jet model for Sgr A*, we calculate the synchrotron and synchrotron self-Compton emission. The predicted spectrum provides an excellent fit to the radio spectrum and the the X-ray observations....

The diffuse Galactic γ-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory (CGRO) indicated excess γ-ray emission ≥ 1 GeV relative to diffuse Galactic γ-ray emission models consistent with directly measured CR spectra (the so-c...

Observed X-ray spectra of hot gas in clusters, groups, and individual galaxies are commonly fit with a single-temperature thermal plasma model even though the beam may contain emission from components with different temperatures. Recently, Mazzotta et al. pointed out that thus derived T spec can be significantly different from commonly used definitions of average temperature, such as emission-o...

— We report on BeppoSAX simultaneous X-and γ-ray observations of the bright γ-ray burst (GRB) 990123. We present the broad-band spectrum of the prompt emission, including optical, X-and γ-rays, confirming the suggestion that the emission mechanisms at low and high frequencies must have different physical origins. We discuss the X-ray afterglow observed by the Narrow Field Instruments (NFIs) on ...