The X-Ray Emission of 3C 273 Observed with ASCA
Abstract
We report preliminary results of an ASCA observation of 3C 273. There is no spectral variability within the ASCA observation, in contrast to the longer term behavior found with EXOSAT and Ginga which established significant changes in the spectral index of the power-law continuum on timescales of a week or more, uncorrelated with luminosity. Comparison of the ASCA data with a simultaneous ROSAT/Ginga observation in 1990 December shows that while the shape of the spectrum above ~ 1 keV is essentially the same, the flux in the soft component, below ~ 1 keV, is considerably weaker relative to the hard component in the ASCA observation. The 2--10 keV luminosity is at least a factor of ~ 1.5 greater in the ASCA observation than in the ROSAT/Ginga observation whilst the ratio of 2--10 keV luminosity to 0.4--1.0 keV luminosity increases by a factor of ~ 1.2. Thus the spectral shape of the hard component appears to be independent of the relative magnitude of the soft component and is an important constraint on emission and reprocessing models. We find no significant Fe K line-emission in this observation. The data also highlight very well some of the outstanding problems in the instrumental responses.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- June 1994
- Bibcode:
- 1994PASJ...46L..49Y
- Keywords:
-
- Active Galaxies;
- Astronomical Observatories;
- Quasars;
- X Ray Astronomy;
- Charge Coupled Devices;
- X Ray Absorption;
- X Ray Telescopes;
- Astrophysics;
- QUASARS: INDIVIDUAL (3C 273);
- X-RAYS: ACTIVE GALAXIES;
- X-RAYS: GENERAL