Previous abstract Next abstract
We present results from the Extreme Ultraviolet Explorer (EUVE) all-sky survey on active galactic nuclei (AGN) and BL Lac Objects. These objects were all detected in the short wavelength telescopes, which cover the 50-180~\AA\/ spectral region. We have detected two AGN (Markarian 279 and 1H0419-577) and four BL Lac objects (Markarian 421, Markarian 180, Markarian 501, and PKS 2155-304).
The EUVE detections of Markarian 279, 1H0419-577, Markarian 180, and Markarian 501 mark the first time these objects have been seen in emission in the EUV. We confirm the ROSAT Wide Field Camera detections of PKS 2155-304 and Markarian 421. The Wide Field Camera detections of Markarian 478 and NGC 5548 could not be confirmed by EUVE due to survey exposure gaps. However, we do not confirm the Wide Field Camera detections of the AGN X12325, IC 3599, RE2248-511, and 3C 273. We present results of our investigation that this discrepancy is due to variability in the EUV emission component of the AGN or to soft X-ray bandpass leaks in the Wide Field Camera.
The number of AGN detected by EUVE was fewer than expected. A possible explanation for this is that the EUV emission from low luminosity AGN is being absorbed by the neutral gas intrinsic to the AGN. By analogy with the hard X-ray surveys, there is a correlation between a high intrinsic column density and low luminosity. This is also consistent with the model that BL Lacs have very little intrinsic gas, so their EUV emission can be detected.
This work has been supported by NASA contract NAS5-30180.
Tuesday program listing