Detection of an extremely soft X-ray outburst in the HII-like nucleus of NGC 5905.
Abstract
NGC 5905 was observed with ROSAT five times, three times during the ROSAT all-sky survey (RASS) and twice in the pointed observing mode. The soft X-ray properties of the nucleus of NGC 5905 derived from the RASS observations, namely high-amplitude flux variability on timescales of days, the extremely soft spectrum (photon index {GAMMA}=4), and high peak luminosity of L_X_=7x10^42^ergs/s, are all inconsistent with its optical classification as HII-type, i.e. starburst galaxy. During the pointed observations taken two years later, the X-ray luminosity was down by a factor of >80. Possible mechanisms, which can produce the high state, are discussed. Tidal disruption of a star near a central black hole is in good agreement with the observations.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- May 1996
- Bibcode:
- 1996A&A...309L..35B
- Keywords:
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- GALAXIES: GENERAL;
- GALAXIES: STARBURST;
- GALAXIES: INDIVIDUAL: NGC5905;
- QUASARS: GENERAL;
- X-RAYS: GALAXIES