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ASCA Guest Observer Facility

ASCA Science Highlights

compiled by :

K.A. Arnaud (1,2), A. Brown (3), K. Ebisawa (1,4), E.V. Gotthelf (1,4), J. Halpern (5),
J.P. Hughes (6), C. Jones(6), G.M. Madejski (1,4), C. Mauche (7), K. Mukai (1,4),
R.F. Mushotzky (1), N.E. White (1)

1) NASA/GSFC, 2) University of Maryland, 3) University of Colorado,
4) Universities Space Research Association,5) Columbia University,
6) Smithsonian Astrophysical Observatory, 7) Lawrence Livermore National Laboratory

Diffuse X-ray background

Active Galactic Nuclei including the first direct detection of relativistic line broadening of an X-ray emission line in an active galactic nucleus, indicating that the observed iron K line radiation emanates from within tens of Schwarzschild radii of the massive central object. Also the detection of X-ray emission from the radio lobes of Fornax A and Centaurus B with a spectrum consistent with that from inverse Compton from the radio synchrotron electrons, providing the first measurement of the magnetic field strength in the lobes of radio galaxies.

Clusters of Galaxies including highly robust determinations of the mass of clusters of galaxies and the demonstration that most of the intracluster gas in rich clusters has been processed by Type II supernovae at early epochs.

Galaxies (including galactic center) including the discovery that metal abundances in the gas haloes of elliptical galaxies are sub-solar with, in the few cases that have been measured so far, a decrease in abundance with radius. Also evidence that the center of the Milky Way is filled with ionized hot gas whose heating mechanism remains unknown; the detection of strong localized iron K fluorescent radiation suggesting the presence of a low luminosity active nucleus in our Galaxy as recently as a few hundred years ago.

Supernova Remnants including the measurement, using images in prominent X-ray emission lines, of significant variation in supernova remnants of both ionization and chemical composition as a function of position, as well as coherent velocity features that directly measure the expansion of the ejecta; the identification of a site of cosmic ray acceleration in the supernova remnant SN1006.

Stars including measurements of abundances in the coronae of active stars suggesting metal deficiencies when compared to photospheric abundances. Also the completely unexpected discovery of hard X-ray emission, including a flare, from class I protostellar candidates.

X-ray Binaries including the discovery of a ~30 msec period in Cen X-4 demonstrating the theoretically predicted link between low mass X-ray binaries and radio millisecond pulsars.

CVs and supersoft sources

Gamma-ray bursts including the identification of a soft gamma-ray repeater with a neutron star in a supernova remnant

This file was last modified on Monday, 13-Sep-1999 15:37:28 EDT
Curator: Michael Arida (SP Sys);
HEASARC Guest Observer Facility
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This file was last modified on Monday, 13-Sep-1999 15:37:28 EDT

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