نتایج جستجو برای: ray emission
تعداد نتایج: 447481 فیلتر نتایج به سال:
We review the polarization properties of X-ray emission from highly magnetized neutron stars, focusing on emission from the stellar surfaces. We discuss how x-ray polarization can be used to constrain neutron star magnetic field and emission geometry, and to probe strong-field quantum electrodynamics and possibly constrain the properties of axions.
The detection of X-ray emission from Hickson's compact groups of galaxies (HCGs) and its origin are the subject of this work. A search for X-ray emission from compact groups revealed detection from 8 out of the 12 HCG images extracted from the ROSAT public archive. For two of them (HCG16 and HCG44), the Xray emission originates from point-like sources spatially coincident with galaxies in the g...
Multiwavelength observations of the black hole X-ray binary XTE J1118+480 have offered abundant spectral and timing information about the source and have thus provided serious challenges to theoretical models. We propose a coupled accretion-jet model to interpret the observations. We model the accretion flow as an outer standard thin accretion disk truncated at a transition radius by an inner h...
Shock breakout X-ray emission has been reported for the first time from a supernova connected with a gamma-ray burst, namely GRB060218/SN2006aj. The gamma-ray emission and the power-law decaying X-ray afterglow are ascribed to a highly relativistic jet, while the thermal soft X-rays are thought to be produced when the radiation-dominated shock breaks from the optically thick stellar wind. We st...
The nearly face-on SBc galaxy M83 (NGC 5236) was observed for 25 ksec with the ROSAT PSPC. We detected 13 point-like sources in this galaxy, 10 of which were previously unknown, down to a limiting luminosity of ∼ 0.8 · 10 38 erg s −1 (for D=8.9 Mpc). Eight of these sources are positionally associated with H ii regions and/or H i voids, suggesting an association with the younger stellar populati...
We describe Chandra High-Energy Transmission Grating Spectrometer observations of RT Cru, the first of a new sub-class of symbiotic stars that appear to contain white dwarfs (WDs) capable of producing hard X-ray emission out to greater than 50 keV. The production of such hard X-ray emission from the objects in this sub-class (which also includes CD −57 3057, T CrB, and CH Cyg) challenges our un...
We report Chandra ACIS observations of the fields of 4 QSOs showing strong extended optical emission-line regions. Two of these show no evidence for significant extended X-ray emission. The remaining two fields, those of 3C 249.1 and 4C 37.43, show discrete (but resolved) X-ray sources at distances ranging from ∼ 10 to ∼ 40 kpc from the nucleus. In addition, 4C 37.43 also may show a region of d...
We report the detection of luminous extended X-ray emission in NGC 6240 on the basis of ROSAT HRI observations of this ultraluminous IR galaxy. The spatial structure and temporal behavior of the X-ray source were analyzed. We find that >∼ 70% of the soft X-ray emission is extended beyond a radius of 5. Strong emission can be traced out to a radius of 20 and weaker emission extends out to ∼50. W...
Context. It has been claimed that the nova-like cataclysmic variable (CV) AE Aquarii (AE Aqr) is a very-high-energy (VHE, E >100 GeV) source both on observational and theoretical grounds. Aims. We search for VHE γ-ray emission from AE Aqr during different states of the source at several wavelengths to confirm or rule out previous claims of detection of γ-ray emission from this object. Methods. ...
We investigate a sample of 14 clusters of galaxies observed with XMM-Newton in a search for soft X-ray excess emission. In five of these clusters a significant soft excess is evident. This soft X-ray excess is compared with the thermal emission from both the hot intracluster gas and any cooling (flow) gas that may be present. A warm (kT =0.2 keV), extended (several Mpc), plasma component is par...
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