Optical and X‐Ray Spectroscopy of 1E 0449.4−1823: Demise of the Original Type 2 QSO
| Autor: | Karl Forster, Michael Eracleous, Jules P. Halpern |
|---|---|
| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | The Astrophysical Journal. 501:103-109 |
| ISSN: | 1538-4357 0004-637X |
| Popis: | New optical spectra of the original narrow-line quasar 1E 0449.4-1823 show that it now has broad emission lines of considerable strength, eliminating it as a "type 2 QSO" candidate. We suggest that the behavior of 1E 0449.4-1823 is the same as that of some Seyfert 1.8 and 1.9 galaxies, in which Goodrich attributed long-term variations of their broad Balmer lines to dynamical motions of obscuring material located in or around the broad-line region. The optical continuum and broad emission-line regions of 1E 0449.4-1823 may still be partly covered in our line of sight, which would explain its large forbidden-line equivalent widths and flat alpha_ox relative to other low-redshift QSOs. Also present are apparent absorption features in the broad Balmer lines and in Mg II, which may be related to the past obscuration and current emergence of the broad-line region. However, it is difficult to distinguish absorption from broad emission-line peaks that are displaced in velocity; we consider the latter a plausible competing interpretation of these peculiar line profiles. An ASCA X-ray spectrum of 1E 0449.4-1823 can be fitted with a power-law of Gamma = 1.63, intrinsic N_H < 9 x 10^20 cm-2, and no Fe Kalpha line emission. Its 2-10 keV luminosity is 6.7 x 10^44 ergs/s. With regard to the still hypothetical type 2 QSOs, we argue that there is little evidence for the existence of any among X-ray selected samples. to appear in ApJ July 1, 1998 (vol. 501). 23 pages including figures. Uses LaTeX macro aasms4.sty |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|