Variable ultraviolet absorption in the Seyfert 1 galaxy NGC 3516

The case for associated ultraviolet and X-ray absorption

S. B. Kraemer, D. M. Crenshaw, I. M. George, H. Netzer, T. J. Turner, Jack Gabel

Research output: Contribution to journalReview article

43 Citations (Scopus)

Abstract

We present observations of the UV absorption lines in the Seyfert 1 galaxy NGC 3516, obtained at a resolution of λ/Δλ ≈ 40, 000 with the Space Telescope Imaging Spectrograph (STIS) on 2000 October 1. The UV continuum was ∼4 times lower than that observed during 1995 with the Goddard High Resolution Spectrograph (GHRS), and the X-ray flux from a contemporaneous Chandra X-Ray Observatory observation was a factor of ∼8 below that observed with ASCA. The STIS spectra show kinematic components of absorption in Lyα, C IV, and N V at radial velocities of -376, -183, and -36 km s-1 (components 1, 2, and 3+4, respectively), which were detected in the earlier GHRS spectra; the last of these is a blend of two GHRS components that have increased greatly in column density. Four additional absorption components have appeared in the STIS spectra at radial velocities of -692, -837, -994, and -1372 km s-1 (components 5-8); these may also have been present in earlier low-flux states observed by the International Ultraviolet Explorer. Based on photoionization models, we suggest that the components are arranged in increasing radial distance in the order 3+4, 2, 1, followed by components 5-8. We have achieved an acceptable fit to the X-ray data using the combined X-ray opacity of the UV components 1, 2, and 3+4. By increasing the UV and X-ray fluxes of these models to match the previous high states, we are able to match the GHRS C IV column densities, the absence of detectable C IV absorption in components 5-8, and the 1994 ASCA spectrum. We conclude that variability of the UV and X-ray absorption in NGC 3516 is primarily due to changes in the ionizing flux.

Original languageEnglish
Pages (from-to)98-113
Number of pages16
JournalAstrophysical Journal
Volume577
Issue number1 I
DOIs
StatePublished - Sep 20 2002
Externally publishedYes

Fingerprint

ultraviolet absorption
spectrographs
galaxies
x rays
high resolution
telescopes
radial velocity
IUE
observatory
kinematics
opacity
photoionization
observatories
continuums

All Science Journal Classification (ASJC) codes

  • Space and Planetary Science
  • Nuclear and High Energy Physics

Cite this

Variable ultraviolet absorption in the Seyfert 1 galaxy NGC 3516 : The case for associated ultraviolet and X-ray absorption. / Kraemer, S. B.; Crenshaw, D. M.; George, I. M.; Netzer, H.; Turner, T. J.; Gabel, Jack.

In: Astrophysical Journal, Vol. 577, No. 1 I, 20.09.2002, p. 98-113.

Research output: Contribution to journalReview article

Kraemer, S. B. ; Crenshaw, D. M. ; George, I. M. ; Netzer, H. ; Turner, T. J. ; Gabel, Jack. / Variable ultraviolet absorption in the Seyfert 1 galaxy NGC 3516 : The case for associated ultraviolet and X-ray absorption. In: Astrophysical Journal. 2002 ; Vol. 577, No. 1 I. pp. 98-113.
@article{948231606f8f491fba78737bad118fb2,
title = "Variable ultraviolet absorption in the Seyfert 1 galaxy NGC 3516: The case for associated ultraviolet and X-ray absorption",
abstract = "We present observations of the UV absorption lines in the Seyfert 1 galaxy NGC 3516, obtained at a resolution of λ/Δλ ≈ 40, 000 with the Space Telescope Imaging Spectrograph (STIS) on 2000 October 1. The UV continuum was ∼4 times lower than that observed during 1995 with the Goddard High Resolution Spectrograph (GHRS), and the X-ray flux from a contemporaneous Chandra X-Ray Observatory observation was a factor of ∼8 below that observed with ASCA. The STIS spectra show kinematic components of absorption in Lyα, C IV, and N V at radial velocities of -376, -183, and -36 km s-1 (components 1, 2, and 3+4, respectively), which were detected in the earlier GHRS spectra; the last of these is a blend of two GHRS components that have increased greatly in column density. Four additional absorption components have appeared in the STIS spectra at radial velocities of -692, -837, -994, and -1372 km s-1 (components 5-8); these may also have been present in earlier low-flux states observed by the International Ultraviolet Explorer. Based on photoionization models, we suggest that the components are arranged in increasing radial distance in the order 3+4, 2, 1, followed by components 5-8. We have achieved an acceptable fit to the X-ray data using the combined X-ray opacity of the UV components 1, 2, and 3+4. By increasing the UV and X-ray fluxes of these models to match the previous high states, we are able to match the GHRS C IV column densities, the absence of detectable C IV absorption in components 5-8, and the 1994 ASCA spectrum. We conclude that variability of the UV and X-ray absorption in NGC 3516 is primarily due to changes in the ionizing flux.",
author = "Kraemer, {S. B.} and Crenshaw, {D. M.} and George, {I. M.} and H. Netzer and Turner, {T. J.} and Jack Gabel",
year = "2002",
month = "9",
day = "20",
doi = "10.1086/342173",
language = "English",
volume = "577",
pages = "98--113",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1 I",

}

TY - JOUR

T1 - Variable ultraviolet absorption in the Seyfert 1 galaxy NGC 3516

T2 - The case for associated ultraviolet and X-ray absorption

AU - Kraemer, S. B.

AU - Crenshaw, D. M.

AU - George, I. M.

AU - Netzer, H.

AU - Turner, T. J.

AU - Gabel, Jack

PY - 2002/9/20

Y1 - 2002/9/20

N2 - We present observations of the UV absorption lines in the Seyfert 1 galaxy NGC 3516, obtained at a resolution of λ/Δλ ≈ 40, 000 with the Space Telescope Imaging Spectrograph (STIS) on 2000 October 1. The UV continuum was ∼4 times lower than that observed during 1995 with the Goddard High Resolution Spectrograph (GHRS), and the X-ray flux from a contemporaneous Chandra X-Ray Observatory observation was a factor of ∼8 below that observed with ASCA. The STIS spectra show kinematic components of absorption in Lyα, C IV, and N V at radial velocities of -376, -183, and -36 km s-1 (components 1, 2, and 3+4, respectively), which were detected in the earlier GHRS spectra; the last of these is a blend of two GHRS components that have increased greatly in column density. Four additional absorption components have appeared in the STIS spectra at radial velocities of -692, -837, -994, and -1372 km s-1 (components 5-8); these may also have been present in earlier low-flux states observed by the International Ultraviolet Explorer. Based on photoionization models, we suggest that the components are arranged in increasing radial distance in the order 3+4, 2, 1, followed by components 5-8. We have achieved an acceptable fit to the X-ray data using the combined X-ray opacity of the UV components 1, 2, and 3+4. By increasing the UV and X-ray fluxes of these models to match the previous high states, we are able to match the GHRS C IV column densities, the absence of detectable C IV absorption in components 5-8, and the 1994 ASCA spectrum. We conclude that variability of the UV and X-ray absorption in NGC 3516 is primarily due to changes in the ionizing flux.

AB - We present observations of the UV absorption lines in the Seyfert 1 galaxy NGC 3516, obtained at a resolution of λ/Δλ ≈ 40, 000 with the Space Telescope Imaging Spectrograph (STIS) on 2000 October 1. The UV continuum was ∼4 times lower than that observed during 1995 with the Goddard High Resolution Spectrograph (GHRS), and the X-ray flux from a contemporaneous Chandra X-Ray Observatory observation was a factor of ∼8 below that observed with ASCA. The STIS spectra show kinematic components of absorption in Lyα, C IV, and N V at radial velocities of -376, -183, and -36 km s-1 (components 1, 2, and 3+4, respectively), which were detected in the earlier GHRS spectra; the last of these is a blend of two GHRS components that have increased greatly in column density. Four additional absorption components have appeared in the STIS spectra at radial velocities of -692, -837, -994, and -1372 km s-1 (components 5-8); these may also have been present in earlier low-flux states observed by the International Ultraviolet Explorer. Based on photoionization models, we suggest that the components are arranged in increasing radial distance in the order 3+4, 2, 1, followed by components 5-8. We have achieved an acceptable fit to the X-ray data using the combined X-ray opacity of the UV components 1, 2, and 3+4. By increasing the UV and X-ray fluxes of these models to match the previous high states, we are able to match the GHRS C IV column densities, the absence of detectable C IV absorption in components 5-8, and the 1994 ASCA spectrum. We conclude that variability of the UV and X-ray absorption in NGC 3516 is primarily due to changes in the ionizing flux.

UR - http://www.scopus.com/inward/record.url?scp=0041730917&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0041730917&partnerID=8YFLogxK

U2 - 10.1086/342173

DO - 10.1086/342173

M3 - Review article

VL - 577

SP - 98

EP - 113

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1 I

ER -