نتایج جستجو برای: ray emission
تعداد نتایج: 447481 فیلتر نتایج به سال:
With frequent flaring activity of its relativistic jets, Cygnus X-3 (Cyg X-3) is one of the most active microquasars and is the only Galactic black hole candidate with confirmed high-energy γ -ray emission, thanks to detections by Fermi Large Area Telescope (Fermi/LAT) and AGILE. In 2011, Cyg X-3 was observed to transit to a soft X-ray state, which is known to be associated with high-energy γ -...
We present Hubble Space Telescope images of the Heiii region surrounding the bright X-ray source in the dwarf irregular galaxy Holmberg II. Using Chandra, we find a position for the X-ray source of α = 08h 19m 28.98s, δ = +70 • 42 ′ 19. ′′ 3 (J2000) with an uncertainty of 0.6 ′′. We identify a bright, point-like optical counterpart centered in the nebula with the X-ray source. The optical magni...
The discovery of high energy X-ray emission in 1996 from C/1996 B2 (Hyakutake) has created a surprising new class of X-ray emitting objects. The original discovery (Lisse et al., 1996) and subsequent detection of X-rays from 17 other comets (Table 1) have shown that the very soft (E < 1 keV) emission is due to an interaction between the solar wind and the comet’s atmosphere, and that X-ray emis...
We present new optical and X-ray observations to show that the X-ray source 1WGA J1346.5−6255 previously associated with the SNR G309.2-0.6 can be unequivocally identified with the emission line star HD 119682 located in the foreground open cluster NGC 5281. Images from Chandra in the X-ray band as well as from Magellan in the narrow optical Hα band show a coincidence of the source positions wi...
The Origin of X-ray Emission from a Galactic Center Molecular Cloud: Low Energy Cosmic Ray Electrons
The Galactic center region near l≈ 0.2 hosts a mixture of nonthermal linear filaments and thermal radio continuum features associated with the radio Arc. Chandra observations of this region reveal an X-ray filament and diffuse emission with an extent of roughly 60′′ × 2′′ and 5′ × 3′, respectively. The X-ray filament lies at the edge of the nonthermal radio filaments and a dense molecular shell...
We report the discovery of extended X-ray emission around the powerful high-redshift quasar GB 1508+5714 at z=4.3, revealed in a long Chandra ACIS observation. The emission feature is 3–4 arcsec away from the quasar core, which corresponds to a projected distance of about 25 kpc. The X-ray spectrum is best fitted with a power law of photon index 1.92 ± 0.35 (90 per cent c.l.). The X-ray flux an...
In this paper we study synchrotron and Self Compton (SSC) emission from internal shocks (IS) during the prompt and X-ray flare phases of Gamma-Ray Bursts (GRBs). The aim is to test the IS model for the flare emission and if GRBs can be GeV sources. We determine the parameters for which the IS model can account for the observed prompt and X-ray flares emission, and study the detectability of the...
We present the first high-resolution, X-ray image of the circumnuclear regions of the Seyfert 1 galaxy NGC 3516, using the Chandra X-ray Observatory (CXO). All three of the CXO observations reported were performed with one of the two grating assemblies in place, and here we restrict our analysis to undispersed photons (i.e. those detected in the zeroth-order). A previously-unknown X-ray source ...
The diffuse X-ray background (DXB) emission near the Galactic plane (l, b ∼ 25.6 • , 0.78 •) has been observed with ASCA. The observed region is toward a Galactic molecular cloud which was recently reported to cast a deep X-ray shadow in the 0.5 − 2.0 keV band DXB. The selection of this particular region is intended to provide a constraint on the spatial distribution of the DXB emission along t...
We present the results of a Suzaku spectroscopic study of the soft extended X-ray emission in the H II region M17. The spectrum of the extended emission was obtained with a high signal-to-noise ratio in a spatially-resolved manner using the X-ray Imaging Spectrometer (XIS). We established that the contamination by unresolved point sources, the Galactic Ridge X-ray emission, the cosmic X-ray bac...
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