The steep spectrum quasar PG1404+226 with ASCA, HST and ROSAT
Abstract
We present and discuss our observations of the Narrow Line quasar PG1404+226 (zem = 0.098) with ASCA and HST, and a re-analysis of our earlier observations with ROSAT. The soft X-ray spectrum is very steep and displays an absorption feature (edge or line at ~ 1.1 keV). We have applied a variety of models to the ASCA and ROSAT spectra without finding a completely satisfactory fit, and the identification of the edge remains uncertain. A satisfactory fit of the ASCA spectrum assuming that the edge is produced by highly ionized iron (using the code absori in XSPEC) is obtained with an overabundance of iron by a factor >= 25 compared to solar, a suggestion supported by the extremely high equivalent width of the Fe Kalpha line at 6.4 keV. A warm absorber model (based on Cloudy) fitting the absorption feature with NeVII-NeX edges and assuming a peculiar oxygen/neon abundance ratio is consistent with the ROSAT data but not the ASCA data. Finally, it is also possible that the observed edge is caused by a OVIII or OVII edge or line, blueshifted by zabs = 0.2 to 0.5 depending on the specific identification, as has been suggested previously for 2 other Narrow Line quasars, but there are no other features in the UV and X-ray spectra in support of this suggestion. Two systems of UV absorption lines, one nearly at rest in the source frame, the other blueshifted by ~ 1900 km s(-1) are identified in the HST/FOS spectra. Photoionization models indicate that the UV absorption and the ~ 1 keV absorption are probably caused by absorbers with different physical conditions. PG1404+226 is one more case of AGN where both UV and X-ray absorption features are detected, thereby increasing further the significance of the previously noted statistical association of the two types of absorbers.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 1999
- DOI:
- 10.48550/arXiv.astro-ph/9907150
- arXiv:
- arXiv:astro-ph/9907150
- Bibcode:
- 1999A&A...350..816U
- Keywords:
-
- GALAXIES: ACTIVE;
- GALAXIES: QUASARS: INDIVIDUAL: PG 1404+226;
- GALAXIES: SPIRAL;
- ULTRAVIOLET: GALAXIES;
- X-RAYS: GALAXIES;
- Astrophysics
- E-Print:
- 11 pages, A&