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Soft X-ray Emission (soft + x-ray_emission)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

A new interpretation of the remarkable X-ray spectrum of the symbiotic star CH Cyg

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006
Peter J. Wheatley
ABSTRACT We have re-analysed the ASCA X-ray spectrum of the bright symbiotic star CH Cyg, which exhibits apparently distinct hard and soft X-ray components. Our analysis demonstrates that the soft X-ray emission can be interpreted as scattering of the hard X-ray component in a photoionized medium surrounding the white dwarf. This is in contrast to previous analyses in which the soft X-ray emission was fitted separately and assumed to arise independently of the hard X-ray component. We note the striking similarity between the X-ray spectra of CH Cyg and Seyfert 2 galaxies, which are also believed to exhibit scattering in a photoionized medium. [source]

XMM,Newton observations of UW CrB: detection of X-ray bursts and evidence for accretion disc evolution

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2005
Pasi Hakala
ABSTRACT UW CrB (MS 1603+2600) is a peculiar short-period X-ray binary that exhibits extraordinary optical behaviour. The shape of the optical light curve of the system changes drastically from night to night, without any changes in overall brightness. Here we report X-ray observations of UW CrB obtained with XMM,Newton. We find evidence for several X-ray bursts, confirming a neutron star primary. This considerably strengthens the case that UW CrB is an accretion disc corona system located at a distance of at least 5,7 kpc (3,5 kpc above the Galactic plane). The X-ray and Optical Monitor (ultraviolet,optical) light curves show remarkable shape variation from one observing run to another, which we suggest are due to large-scale variations in the accretion disc shape resulting from a warp that periodically obscures the optical and soft X-ray emission. This is also supported by the changes in phase-resolved X-ray spectra. [source]

On the relation between the coronal line emission and the infrared/X-ray emission in Seyfert galaxies

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2002
M. Almudena Prieto
The relation between the X-ray, the coronal line and the infrared (IR) emissions in a sample of the brightest known Seyfert galaxies is analysed. A close relationship between the absorption-corrected soft X-ray emission and both the mid-IR and the coronal line emission is found for the Seyfert type 2 objects in the sample. The coronal line and the X-ray emissions are both main tracers of active galactic nuclei (AGN) activity and their relationship with the mid-IR emission points to the heat of the carbuncle dust as the main energetic process associated with the AGN. On the other hand, the above relations do not seem to hold for the type 1 Seyfert discussed in the sample, at least when the comparisons are made in a flux diagram. This is partially because of the reduced number of objects of this type analysed in this work and also the fact that the measured soft X-ray emission in Seyfert 1s is systematically larger, by at least an order of magnitude, than that in the Seyfert 2 counterparts. Finally, the hard X-ray emission in the studied sample appears unrelated to either the mid-IR or the coronal line emission. [source]

The iron emission line complex of MCG-5-23-16: the long XMMNewton look

ASTRONOMISCHE NACHRICHTEN, Issue 10 2006
V. Braito
Abstract We present the results of the simultaneous XMM- Newton and Chandra observations of the bright Seyfert 1.9 galaxy MCG,5-23-16, which is one of the best known examples of a relativistically broadened iron K, line. We find that: a) the soft X-ray emission is likely to be dominated by photoionized gas, b) the complex iron emission line is best modelled with a narrow and a broad component with a FWHM ,44000 km/s. This latter component has an EW ,50 eV and its profile is well described with an emission line mainly originating from the accretion disk a few tens of gravitational radii from the central black hole and viewed with an inclination angle ,40°. We found evidence of a possible sporadic absorption line at ,7.7 keV which, if associated with Fe XXVI K, resonance absorption, is indicative of a possible high velocity (v , 0.1c) outflow. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

HI , the window to the early universe in X-rays

ASTRONOMISCHE NACHRICHTEN, Issue 1-2 2003
J. Kerp
Abstract A detailed understanding of the soft X-ray background (SXRB) is of high importance for the next generation of X-ray telescopes, which will focus on early universe objects. Because of their high redshift the characteristic X-ray emission of the early universe objects will be observable in the soft X-ray energy domain below E = 1 keV. In this energy regime the photoelectric absorption of the galactic interstellar medium attenuates the X-ray emission most strongly. The confusion with the spatially highly variable galactic soft X-ray emission might be an additional severe problem to disentangle the emission of the early universe object and the SXRB. We present the cross correlation of the Leiden/Dwingeloo HI 21-cm line survey with the ROSAT all-sky survey. The analyses disclose the existence of a single temperature plasma within the Milky Way halo. The strength of the photoelectric absorption is quantitatively traced by the distribution of the HI emission across the whole sky. Both findings in combination open the window to the highly redshift early universe objects. [source]