@article{077e6e55f3ea4ab5891a96163a3a20c7,
title = "Discovery of narrow x-ray absorption lines from NGC 3783 with the chandra high energy transmission grating spectrometer",
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.",
keywords = "Galaxies: Active, Galaxies: Individual (NGC 3783), Galaxies: Seyfert, Galaxies: nuclei, Techniques: Spectroscopic, X-rays: Galaxies",
author = "Shai Kaspi and Brandt, \{W. N.\} and Hagai Netzer and Rita Sambruna and George Chartas and Garmire, \{Gordon P.\} and Nousek, \{John A.\}",
note = "Publisher Copyright: {\textcopyright} 2000. The American Astronomical Society.",
year = "2000",
month = may,
day = "20",
doi = "10.1086/312662",
language = "אנגלית",
volume = "535",
pages = "L17--L20",
journal = "Astrophysical Journal Letters",
issn = "2041-8205",
publisher = "American Astronomical Society",
number = "1",
}