The Equilibrium Photoionized Absorber in 3C 351
Abstract
We present two ROSAT Position Sensitive Proportional Counter (PSPC) observations of the radio-loud, lobe-dominated quasar 3C 351, which shows an ``ionized absorber'' in its X-ray spectrum. The factor of 1.7 change in flux in the ~2 years between the observations allows a test of models for this ionized absorber.
The absorption feature at ~0.7 keV (quasar frame) is present in both spectra but with a lower optical depth when the source intensity--and hence the ionizing flux at the absorber--is higher, in accordance with a simple, single-zone, equilibrium photoionization model. Detailed modeling confirms this agreement quantitatively. The maximum response time of 2 years allows us to limit the gas density: ne>2×104 cm-3 and the distance R of the ionized gas from the central source is less than 19 pc. This produces a strong test for a photoionized absorber in 3C 351: a factor of 2 flux change in ~1 week in this source must show nonequilibrium effects in the ionized absorber.- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 1999
- DOI:
- 10.1086/306741
- arXiv:
- arXiv:astro-ph/9809114
- Bibcode:
- 1999ApJ...512..136N
- Keywords:
-
- GALAXIES: QUASARS: INDIVIDUAL: ALPHANUMERIC: 3C 351;
- X-RAYS: GALAXIES;
- Galaxies: Quasars: Individual: Alphanumeric: 3C 351;
- X-Rays: Galaxies;
- Astrophysics
- E-Print:
- 10 pages, 3 figures, accepted by ApJ