A ROSAT observation of NGC 5548

K. Nandra; A. C. Fabian; I. M. George; G. Branduardi-Raymont; A. Lawrence; K. O. Mason; I. M. McHardy; K. A. Pounds; G. C. Stewart; M. J. Ward; R. S. Warwick

doi:10.1093/mnras/260.3.504

A ROSAT observation of NGC 5548

K. Nandra, A. C. Fabian, I. M. George, G. Branduardi-Raymont, A. Lawrence, K. O. Mason, I. M. McHardy, K. A. Pounds, G. C. Stewart, M. J. Ward, R. S. Warwick

Research output: Contribution to journal › Article › peer-review

Abstract

We present a detailed spectral and temporal analysis of a long ROSAT PSPC pointing centered on the bright Seyfert 1 galaxy NGC 5548. The spectrum is particularly complex, with a two-component model favored, confirming the existence of the soft excess in this source. In addition, an absorption feature arising from highly ionized oxygen in the line of sight has been detected, consistent with an origin in the 'warm absorber' which has been found to be a common feature in Seyfert galaxies observed by Ginga. The energy and depth of the feature should allow us to constrain the density and geometry of the absorbing gas, which may lie close to the central continuum source. NGC 5548 was in a low X-ray state during the observation, brightening by a factor of about 2 on a time-scale of about 2 d. Time-resolved spectral analysis shows a change in the ratio of the hard and soft fluxes, consistent with reprocessing models.

Original language	English
Pages (from-to)	504-512
Journal	Monthly Notices of the Royal Astronomical Society
Volume	260
DOIs	https://doi.org/10.1093/mnras/260.3.504
Publication status	Published - 1 Feb 1993

Keywords / Materials (for Non-textual outputs)

Rosat Mission
Seyfert Galaxies
X Ray Astronomy
Light Curve
Spectrum Analysis
X Ray Spectra

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10.1093/mnras/260.3.504

http://adsabs.harvard.edu/abs/1993MNRAS.260..504N

Cite this

@article{ed1b2dd4a4c84c0eb21d668f70f72b9b,

title = "A ROSAT observation of NGC 5548",

abstract = "We present a detailed spectral and temporal analysis of a long ROSAT PSPC pointing centered on the bright Seyfert 1 galaxy NGC 5548. The spectrum is particularly complex, with a two-component model favored, confirming the existence of the soft excess in this source. In addition, an absorption feature arising from highly ionized oxygen in the line of sight has been detected, consistent with an origin in the 'warm absorber' which has been found to be a common feature in Seyfert galaxies observed by Ginga. The energy and depth of the feature should allow us to constrain the density and geometry of the absorbing gas, which may lie close to the central continuum source. NGC 5548 was in a low X-ray state during the observation, brightening by a factor of about 2 on a time-scale of about 2 d. Time-resolved spectral analysis shows a change in the ratio of the hard and soft fluxes, consistent with reprocessing models.",

keywords = "Rosat Mission, Seyfert Galaxies, X Ray Astronomy, Light Curve, Spectrum Analysis, X Ray Spectra",

author = "K. Nandra and Fabian, {A. C.} and George, {I. M.} and G. Branduardi-Raymont and A. Lawrence and Mason, {K. O.} and McHardy, {I. M.} and Pounds, {K. A.} and Stewart, {G. C.} and Ward, {M. J.} and Warwick, {R. S.}",

year = "1993",

month = feb,

day = "1",

doi = "10.1093/mnras/260.3.504",

language = "English",

volume = "260",

pages = "504--512",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press",

}

TY - JOUR

T1 - A ROSAT observation of NGC 5548

AU - Nandra, K.

AU - Fabian, A. C.

AU - George, I. M.

AU - Branduardi-Raymont, G.

AU - Lawrence, A.

AU - Mason, K. O.

AU - McHardy, I. M.

AU - Pounds, K. A.

AU - Stewart, G. C.

AU - Ward, M. J.

AU - Warwick, R. S.

PY - 1993/2/1

Y1 - 1993/2/1

N2 - We present a detailed spectral and temporal analysis of a long ROSAT PSPC pointing centered on the bright Seyfert 1 galaxy NGC 5548. The spectrum is particularly complex, with a two-component model favored, confirming the existence of the soft excess in this source. In addition, an absorption feature arising from highly ionized oxygen in the line of sight has been detected, consistent with an origin in the 'warm absorber' which has been found to be a common feature in Seyfert galaxies observed by Ginga. The energy and depth of the feature should allow us to constrain the density and geometry of the absorbing gas, which may lie close to the central continuum source. NGC 5548 was in a low X-ray state during the observation, brightening by a factor of about 2 on a time-scale of about 2 d. Time-resolved spectral analysis shows a change in the ratio of the hard and soft fluxes, consistent with reprocessing models.

AB - We present a detailed spectral and temporal analysis of a long ROSAT PSPC pointing centered on the bright Seyfert 1 galaxy NGC 5548. The spectrum is particularly complex, with a two-component model favored, confirming the existence of the soft excess in this source. In addition, an absorption feature arising from highly ionized oxygen in the line of sight has been detected, consistent with an origin in the 'warm absorber' which has been found to be a common feature in Seyfert galaxies observed by Ginga. The energy and depth of the feature should allow us to constrain the density and geometry of the absorbing gas, which may lie close to the central continuum source. NGC 5548 was in a low X-ray state during the observation, brightening by a factor of about 2 on a time-scale of about 2 d. Time-resolved spectral analysis shows a change in the ratio of the hard and soft fluxes, consistent with reprocessing models.

KW - Rosat Mission

KW - Seyfert Galaxies

KW - X Ray Astronomy

KW - Light Curve

KW - Spectrum Analysis

KW - X Ray Spectra

U2 - 10.1093/mnras/260.3.504

DO - 10.1093/mnras/260.3.504

M3 - Article

SN - 0035-8711

VL - 260

SP - 504

EP - 512

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

ER -

A ROSAT observation of NGC 5548

Abstract

Keywords / Materials (for Non-textual outputs)

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