Discovery of narrow x-ray absorption lines from NGC 3783 with the chandra high energy transmission grating spectrometer

Shai Kaspi*, W. N. Brandt, Hagai Netzer, Rita Sambruna, George Chartas, Gordon P. Garmire, John A. Nousek

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

101 Scopus citations

Abstract

We present the first grating-resolution X-ray spectra of the Seyfert 1 galaxy NGC 3783, obtained with the High Energy Transmission Grating Spectrometer on the Chandra X-Ray Observatory. These spectra reveal many narrow absorption lines from the H-like and He-like ions of O, Ne, Mg, Si, S, and Ar as well as Fe xvii- Fe xxi L-shell lines. We have also identified several weak emission lines, mainly from O and Ne. The absorption lines are blueshifted by a mean velocity of ≈440±200 km s-1 and are not resolved, indicating a velocity dispersion within the absorbing gas of a few hundred kilometers per second or less. We measure the lines' equivalent widths and compare them with the predictions of photoionization models. The best-fitting model has a microturbulence velocity of 150 km s21 and a hydrogen column density of 1.3×1022 cm-2. The measured blueshifts and inferred velocity dispersions of the X-ray absorption lines are consistent with those of the strongest UV absorption lines observed in this object. However, simple models that propose to strictly unify the X-ray and UV absorbers have difficulty explaining simultaneously the X-ray and UV absorption-line strengths.

Original languageEnglish
Pages (from-to)L17-L20
JournalAstrophysical Journal Letters
Volume535
Issue number1
DOIs
StatePublished - 20 May 2000

Funding

FundersFunder number
National Aeronautics and Space AdministrationNAS8-38252, NAG5-8107
Alfred P. Sloan Foundation
Israel Science Foundation

    Keywords

    • Galaxies: Active
    • Galaxies: Individual (NGC 3783)
    • Galaxies: Seyfert
    • Galaxies: nuclei
    • Techniques: Spectroscopic
    • X-rays: Galaxies

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