The Soft-X-Ray Spectral Shape of X-Ray-Weak Seyferts

Abstract

(I) We observed eight Seyfert~2s and two X--ray--weak Seyfert~1/QSOs with the ROSAT PSPC, and one Seyfert~2 with the ROSAT HRI. These targets were selected from the Extended 12\um\ Galaxy Sample. (II) Both Seyfert~1/QSOs vary by factors of 1.5---2. The photon indices steepen in the more luminous state, consistent with the variability being mainly due to the softest X--rays, which are confined to a size of less than a parsec. (III) Both the Seyfert~2s and Seyfert~1/QSOs are best fit with a photon index of $\Gamma \sim 3$, which is steeper than the canonical value of $\Gamma \sim 1.7$ measured for X--ray--strong Seyferts by ROSAT and at higher energies. Several physical explanations are suggested for the steeper slopes of X--ray--weak objects. (IV) We observed one Seyfert~2, NGC~5005, with the ROSAT HRI, finding about 13\% of the soft X--rays to come from an extended component. This and other observations suggest that different components to the soft X--ray spectrum of some, if not all, X--ray--weak Seyferts may come from spatially distinct regions.

AASTeX, 13 pages. Text only. PostScript tables and figures available at ftp://eggneb.astro.ucla.edu/pub/rush/papers/, named rm-tables.ps (all 3), rm-figure6.ps (#6 only), and rm-figures.ps (#1-5,7-10). Scheduled for the 1996 January 10 issue of ApJ

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