TY - JOUR
T1 - Discovery of narrow x-ray absorption lines from NGC 3783 with the chandra high energy transmission grating spectrometer
AU - Kaspi, Shai
AU - Brandt, W. N.
AU - Netzer, Hagai
AU - Sambruna, Rita
AU - Chartas, George
AU - Garmire, Gordon P.
AU - Nousek, John A.
N1 - Funding Information:
We thank all the members of the Chandra team for their enormous efforts. We also thank Herman L. Marshall and an anonymous referee for helpful comments. We gratefully acknowledge the financial support of NASA grant NAS8-38252 (G. P. G., PI), NASA LTSA grant NAG5-8107 (S. K., W. N. B.), and the Alfred P. Sloan Foundation (W. N. B.). H. N. acknowledges support from the Israel Science Foundation and the Jack Adler Chair for Extragalactic Astronomy.
Publisher Copyright:
© 2000. The American Astronomical Society.
PY - 2000/5/20
Y1 - 2000/5/20
N2 - 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.
AB - 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.
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U2 - 10.1086/312662
DO - 10.1086/312662
M3 - Article
AN - SCOPUS:0034690373
SN - 2041-8205
VL - 535
SP - L17-L20
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
ER -