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Astron. Astrophys. 341, 8-22 (1999)

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ROSAT observations of the Sculptor galaxy NGC 7793

A.M. Read and W. Pietsch

Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching, Germany

Received 15 July 1998 / Accepted 25 September 1998


We report here the results of spectral imaging observations with the ROSAT PSPC of the field surrounding the very nearby ([FORMULA] Mpc) Sculptor galaxy, NGC 7793. Many point sources are detected within the field, several of them showing evidence for variability. Seven sources are seen to lie within the optical confines of the system, the brightest ([FORMULA] erg s-1), lying to the southern edge of NGC 7793. This source, also observed to be variable, is seen now, not to be associated with a [FORMULA] redshift QSO, as was previously thought. A number of the other sources within the NGC 7793 disc are likely to be due to X-ray binaries, supernova remnants or superbubbles within the galaxy itself. Other sources may be associated with background AGN. In addition to the point source emission, rather uniform unresolved emission is detected in and around NGC 7793 extending to a radius of perhaps 4 kpc. This emission is likely to be contaminated to some degree by unresolved point sources, as its temperature ([FORMULA] keV) is rather hotter than is seen for the diffuse gas components in other nearby spiral galaxies. Comparing the X-ray properties of NGC 7793 with those of the remaining Sculptor group members, suggests that it may, in terms of activity, lie somewhere between its quiescent and starburst neighbours.

Key words: galaxies: clusters: individual: Sculptor – galaxies: individual: NGC 7793 – galaxies: ISM – X-rays: galaxies

Send offprint requests to: A.M. Read (aread@mpe.mpg.de)

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© European Southern Observatory (ESO) 1999

Online publication: November 26, 1998