Rapid soft X-ray variability in a newly discovered active galaxy : EXO 1128+691.
Abstract
A previously unknown active galaxy has been discovered, and has been tentatively identified as a Seyfert type 1. 1t is possibly a member of the UMa I cluster. The X-ray emission differs from that for 'normal' Seyferts in that it is very soft and also shows rapid variability (~15 min to 2 hr). Assuming the galactic value N_H_~1.5x10^20^ cm^-2^ for the column density leads to a power-law spectral index α_E_~4, or T~6x10^5^ K for a thermal spectrum (with a substantial uncertainty in these values because of the variability of EXO 1128+691), for single component models. A separate soft component is suggested by such values. EXO 1125+691 has L_x_~1-3x10^43^ erg s^-1^ (0.05-2 kev) for N_H_~1.5x10^20^ cm^-2^, using the measured redshift z=0.043+/-0.002.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- September 1988
- DOI:
- 10.1093/mnras/234.2.319
- Bibcode:
- 1988MNRAS.234..319B
- Keywords:
-
- Active Galactic Nuclei;
- Black Holes (Astronomy);
- Red Shift;
- Seyfert Galaxies;
- X Ray Sources;
- Exosat Satellite;
- Variable Stars;
- Astrophysics