Is the X-Ray Source of 3C 273 Really Compact?
Abstract
The high-energy spectrum of the quasar 3C 273 and its variations are compared to the predictions of different emission models. High-compactness models are not able to reproduce the observations even when the energy density of the soft photons is relatively small in the X- ray source. The observed spectral variations are, however, explained in a natural way by inverse Compton processes occurring in a source of low compactness (this includes low-compactness, photon-starved pair models). The energy of the bulk of the Comptonizing electrons can be derived independently from the spectral variations and from the γ-ray spectral shape. Both evaluations coincide with ɛ ~ m_e_c^2^. The low-compactness parameter derived from these observations contrasts with the high-compactness derived from the fast X-ray variability timescale. Beaming effects can formally account for the discrepancy. However, it is difficult to use such models to explain other observational constraints. A pancake-shaped, unbeamed X-ray source is an other possible solution.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- June 1994
- DOI:
- 10.1086/192027
- Bibcode:
- 1994ApJS...92..619W
- Keywords:
-
- Gamma Ray Spectra;
- Quasars;
- Spectral Emission;
- Spectral Energy Distribution;
- X Ray Sources;
- Astronomical Models;
- Compton Effect;
- Ultraviolet Spectra;
- Astrophysics;
- GALAXIES: QUASARS: INDIVIDUAL ALPHANUMERIC: 3C 273;
- RADIATION MECHANISMS: NONTHERMAL;
- X-RAYS: GALAXIES