Astronomy and Astrophysics – Astrophysics
Scientific paper
1998-06-15
Astronomy and Astrophysics
Astrophysics
7 pages, 2 figures, to be published in the Astrophysical Journal Letters
Scientific paper
10.1086/311518
NGC 1316 (Fornax A) is a radio galaxy with prototypical double lobes, where the magnetic field intensity is accurately measured via the inverse-Compton technique. The radio-emitting electrons in the lobes are inferred to have a synchrotron life time of 0.1 Gyr. Considering the lobe energetics, we estimate the past nuclear X-ray luminosity of NGC 1316 to be at least 4 times 10^{34} W (4 times 10^{41} erg s^{-1}). Thus, the nucleus was rather active at least 0.1 Gyr ago. In contrast, we confirmed with ASCA and ROSAT that the nucleus of NGC 1316 is very faint in X-rays at present, with the 2--10 keV luminosity of any AGN-like hard component being < 2 times 10^{33} W (2 times 10^{40} erg s^{-1}) even assuming a nuclear obscuration up to 10^{28} m^{-2} (10^{24} cm^{-2}). This is at least an order of magnitude lower than the estimated past activity, indicating that the nucleus is presently very inactive. From these two results, we conclude that the nucleus of NGC 1316 has become dormant during the last 0.1 Gyr. This suggests the possible abundance of ``dormant'' quasars in nearby galaxies.
Inoue Susumu
Iyomoto Naoko
Kaneda Hidehiro
Makishima Kazuo.
Matsumoto Yukari
No associations
LandOfFree
The Declined Activity in the Nucleus of NGC 1316 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Declined Activity in the Nucleus of NGC 1316, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Declined Activity in the Nucleus of NGC 1316 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-634829