Spectral variability in hard X-rays and the evidence for a 13.5 years period in the bright quasar 3C273 |
| |
Authors: | R K Manchanda |
| |
Institution: | (1) Tata Institute of Fundamental Research, Colaba, 400005 Mumbai, India |
| |
Abstract: | We report the observation of nearest quasar 3C273 made with LASE instrument on November 20th, 1998 as a part of our continuing
programme of balloon borne hard X-ray observations in the 20–200 keV band using high sensitivity Large Area Scintillation
counter Experiment. Our data clearly show a steep spectrum in the 20–200 keV with power law spectral indexα = 2.26 ± 0.07. This is in complete contrast to the reported data from OSSE and BeppoSAX which suggest the value of 1.3 to
1.6 for the power law index in the X-ray energy band, but is quite consistent with the value derived for the high energy gamma
ray data. A single power law fit in the X-ray and gamma ray energy bands points to a common origin of these photons and the
absence of spectral break around 1 MeV as suggested in literature. We have reanalyzed the available data to study the temporal
variability of the spectrum in the hard X-ray band. Our analysis reveals that 50 keV flux from the source, shows a strong
modulation with a period of about 13.5 years. The analysis of the optical light curve of the source also supports the 5000
day period. We discuss the emission mechanism and the possible sites for X-ray photons along with the implications of the
long term periodicity with respect to source geometry. |
| |
Keywords: | Galaxies active galactic nuclei jets binary black hole system— quasars individual 3C273 X-rays:galaxies |
本文献已被 SpringerLink 等数据库收录! |