1,615 research outputs found
Infrared studies of supernova remnants with the IRAS
A comparative study of the infrared and X-ray fluxes and morphologies of supernova remnants (SNR) can yield valuable information on their evolution and on their interaction with the smbient interstellar medium (ISM)
A wide-field soft X-ray camera
A wide-field soft X-ray camera (WFSXC) sensitive in the 50 to 250 eV band is described. The camera features Wolter-Schwarzschild optics with an 8 degree field of view and 300 cu cu collecting area. The focal plane instrument is a microchannel plate detector. Broad-band energy discrimination is provided by thin-film filters mounted immediately in front of the focal plane. The WFSXC is capable of detecting sources with intensities greater than 5 percent of HZ 43 during typical sounding rocket exposures, and it would approach the same sensitivity range as EUVE during a typical exposure from the Shuttle
Soft X-ray spectral observations of quasars and high X-ray luminosity Seyfert galaxies
Results of the analysis of 28 Einstein SSS observations of 15 high X-ray luminosity (L(x) 10 to the 435 power erg/s) quasars and Seyfert type 1 nuclei are presented. The 0.75-4.5 keV spectra are in general well fit by a simple model consisting of a power law plus absorption by cold gas. The averager spectral index alpha is 0.66 + or - .36, consistent with alpha for the spectrum of these objects above 2 keV. In all but one case, no evidence was found for intrinsic absorption, with an upper limit of 2 x 10 to the 21st power/sq cm. Neither was evidence found for partial covering of the active nucleus by dense, cold matter (N(H) 10 to the 22nd power/sq cm; the average upper limit on the partial covering fraction is 0.5. There is no obvious correlation between spectral index and 0175-4.5 keV X-ray luminosity (which ranges from 3 x 10 to the 43rd to 47th powers erg/s or with other source properties. The lack of intrinsic X-ray absorption allows us to place constraints on the density and temperature of the broad-line emission region, and narrow line emission region, and the intergalactic medium
Soft X-ray Emission from the Spiral Galaxy NGC 1313
The nearby barred spiral galaxy NGC 1313 has been observed with the PSPC
instr- ument on board the ROSAT X-ray satellite. Ten individual sources are
found. Three sources (X-1, X-2 and X-3 [SN~1978K]) are very bright (~10^40
erg/s) and are unusual in that analogous objects do not exist in our Galaxy. We
present an X-ray image of NGC~1313 and \xray spectra for the three bright
sources. The emission from the nuclear region (R ~< 2 kpc) is dominated by
source X-1, which is located ~1 kpc north of the photometric (and dynamical)
center of NGC~1313. Optical, far-infrared and radio images do not indicate the
presence of an active galactic nucleus at that position; however, the compact
nature of the \xray source (X-1) suggests that it is an accretion-powered
object with central mass M >~ 10^3 Msun. Additional emission (L_X ~ 10^39
erg/s) in the nuclear region extends out to ~2.6 kpc and roughly follows the
spiral arms. This emission is from 4 sources with luminosity of several x 10^38
erg/s, two of which are consistent with emission from population I sources
(e.g., supernova remnants, and hot interstellar gas which has been heated by
supernova remnants). The other two sources could be emission from population II
sources (e.g., low-mass \xray binaries). The bright sources X-2 and SN~1978K
are positioned in the southern disk of NGC~1313. X-2 is variable and has no
optical counterpart brighter than 20.8 mag (V-band). It is likely that it is an
accretion-powered object in NGC~1313. The type-II supernova SN~1978K (Ryder
\etal 1993) has become extra- ordinarily luminous in X-rays 13 years
after optical maximum.Comment: to appear in 10 Jun 1995 ApJ, 30 pgs uuencoded compressed postscript,
25 pgs of figures available upon request from colbert, whole preprint
available upon request from Sandy Shrader ([email protected]),
hopefully fixed unknown problem with postscript fil
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