Astronomy and Astrophysics
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 observa- tions 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 satis- factory fit, and the identification of the edge remains un- certain. 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 Kα 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 ra- tio 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. Photoioniza- tion models indicate that the UV absorption and the ∼ 1 keV absorption are probably caused by absorbers with dif- ferent 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.
Ulrich, Marie-Helene; Comastri, Andrea; Komossa, Stefanie; and Crane, Phil, "The Steep Spectrum Quasar PG1404+ 226 with ASCA, HST and ROSAT" (1999). Open Dartmouth: Faculty Open Access Articles. 540.