Simultaneous ultraviolet and x-ray spectroscopy of the Seyfert 1 galaxy NGC 5548. I. Physical conditions in the ultraviolet absorbers

D. M. Crenshaw, S. B. Kraemer, J. R. Gabel, J. S. Kaastra, K. C. Sieenbrugge, A. C. Brinkman, J. P. Dunn, I. M. George, D. A. Liedahl, F. B.S. Paerels, T. J. Turner, T. Yaqoob

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

We present new UV spectra of the nucleus of the Seyfert 1 galaxy NGC 5548, which we obtained with the Space Telescope Imaging Spectrograph at high spectral resolution, in conjunction with simultaneous Chandra X-Ray Observatory spectra. Taking advantage of the low UV continuum and broad emission-line fluxes, we have determined that the deepest UV absorption component covers at least a portion of the inner, high-ionization narrow-line region (NLR). We find nonunity covering factors in the cores of several kinematic components, which increase the column density measurements of N v and C IV by factors of 1.2-1.9 over the full-covering case; however, the revised columns have only a minor effect on the parameters derived from our photoionization models. For the first time, we have simultaneous N v and C IV columns for component 1 (at -1040 km s-1) and find that this component cannot be an X-ray warm absorber, contrary to our previous claim based on nonsimultaneous observations. We find that models of the absorbers based on solar abundances severely overpredict the O VI columns previously obtained with the Far Ultraviolet Spectroscopic Explorer and present arguments that this is not likely due to variability. However, models that include either enhanced nitrogen (twice solar) or dust, with strong depletion of carbon in either case, are successful in matching all of the observed ionic columns. These models result in substantially lower ionization parameters and total column densities compared to dust-free solar-abundance models and produce little O VII or O VII, indicating that none of the UV absorbers are X-ray warm absorbers.

Original languageEnglish (US)
Pages (from-to)116-127
Number of pages12
JournalAstrophysical Journal
Volume594
Issue number1 I
DOIs
StatePublished - Sep 1 2003
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'Simultaneous ultraviolet and x-ray spectroscopy of the Seyfert 1 galaxy NGC 5548. I. Physical conditions in the ultraviolet absorbers'. Together they form a unique fingerprint.

  • Cite this

    Crenshaw, D. M., Kraemer, S. B., Gabel, J. R., Kaastra, J. S., Sieenbrugge, K. C., Brinkman, A. C., Dunn, J. P., George, I. M., Liedahl, D. A., Paerels, F. B. S., Turner, T. J., & Yaqoob, T. (2003). Simultaneous ultraviolet and x-ray spectroscopy of the Seyfert 1 galaxy NGC 5548. I. Physical conditions in the ultraviolet absorbers. Astrophysical Journal, 594(1 I), 116-127. https://doi.org/10.1086/376792