Soft X-ray properties of Seyfert galaxies. I - Spectra

Kruper, John; Canizares, C. R.; Urry, C. Megan

doi:10.1086/191503

Cited by 49 publications

(39 citation statements)

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“…This is not the first claim that the nucleus of NGC 3516 is seen through a substantial ‘cold’ column density. The same conclusion was reached by Kruper et al (1990), on the basis of Einstein MPC observations and by Ghosh & Soundararajaperumal (1991) using EXOSAT . A 1989 Ginga spectrum also required a column density of (Kolman et al 1993).…”

Section: Discussionsupporting

confidence: 70%

“…Low‐resolution, bandwidth‐limited observations in the 1980s suggested an extreme variability, more pronounced in the soft X‐ray band. Two observations with the Imaging Proportional Counter on‐board Einstein showed an increase by a factor of 5 of the 0.2–4.0 keV flux, accompanied by a large change in spectral shape (the lower the flux, the flatter the spectrum; Kruper et al 1990). Monitoring with the Monitor Proportional Counter (MPC) on board Einstein and with EXOSAT (Ghosh & Soundararajaperumal 1991) revealed strong and highly variable photoelectric absorption.…”

Section: Introductionmentioning

confidence: 99%

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The recent history of the X-ray absorber in NGC 3516

Guainazzi

Marshall

Parmar

2001

Monthly Notices of the Royal Astronomical Society

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We present two BeppoSAX observations of the bright Seyfert 1 galaxy NGC 3516, performed four months apart (late 1996–early 1997). The earlier spectrum is considerably weaker and harder in the whole 0.1–50 keV energy range. In addition, the warm absorber oxygen features, which were already observed with ROSAT and ASCA, are much less pronounced. The most straightforward explanation is that in 1996 November NGC 3516 was being seen through a substantial (NH≃1022 cm−2) column of cold material. This is the first confirmation with modern instrumentation that NGC 3516 indeed undergoes phases of strong cold X‐ray absorption. We speculate that these intervals may be connected to the onset of the remarkably variable UV absorption system, making NGC 3516 the best known example of a low‐luminosity broad absorption line (BAL) quasar. The absorbing matter could be provided by clouds ablated from the rim of the circumnuclear molecular torus, seen at a rather high inclination angle.

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Section: Discussionsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

The recent history of the X-ray absorber in NGC 3516

Guainazzi

Marshall

Parmar

2001

Monthly Notices of the Royal Astronomical Society

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“…I Zw 1 has a systemic velocity of 18,290 km s À1 , which corresponds to a redshift of 0.0611 (Condon et al 1985) or a distance of 255 Mpc (h 0 ¼ 0:72; Spergel et al 2003). The nucleus of I Zw 1 is extremely bright in the optical (M B of À23.45 mag; Schmidt & Green 1983;Barvainis et al 1989) and also has very bright X-ray emission (Kruper et al 1990). I Zw 1 belongs to the class of infrared-luminous galaxies (L FIR ¼ 10 11:3 L ; Haas et al 2003); however, its QSO nature is not apparent in the far-infrared (FIR).…”

Section: The Nearby Qso I Zwmentioning

confidence: 99%

Resolving the Host Galaxy of the Nearby QSO I Zw 1 with Subarcsecond Multitransition Molecular Line Observations

Staguhn

Schinnerer

Eckart

et al. 2004

ApJ

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We present the first subkiloparsec ($0B7 % 850 pc) resolution 12 CO(1 0) molecular line observations of the interstellar medium (ISM) in the host galaxy of the QSO I Zw 1. The observations were obtained with the BIMA millimeter interferometer in its compact A configuration. The BIMA data are complemented by new observations of the 12 CO(2 1) and 13 CO(1 0) lines with the IRAM Plateau de Bure Interferometer (PdBI) at 0B9 and 2B1 resolution, respectively. These measurements, which are part of a multiwavelength study of the host galaxy of I Zw 1, are aimed at comparing the ISM properties of a QSO host with those of nearby galaxies, as well as to obtain constraints on galaxy formation /evolution models. Our images of the 12 CO(1 0) line emission show a ringlike structure in the circumnuclear molecular gas distribution with an inner radius of about 1.2 kpc. The presence of such a molecular gas ring was predicted from earlier lower angular resolution PdBI 12 CO(1 0) observations. A comparison of the BIMA data with IRAM PdBI 12 CO(2 1) observations shows variations in the excitation conditions of the molecular gas in the innermost 1B5 comprising the nuclear region of I Zw 1. The observed properties of the molecular cloud complexes in the disk of the host galaxy suggest that they may be the sites of massive circumnuclear star formation and show no indications of excitation by the active galactic nucleus (AGN). This all indicates that the molecular gas in a QSO host galaxy has properties similar to the gas observed in nearby low-luminosity AGNs.

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“…The X-ray emission was clearly extended but details of the shape were unclear. Crude spectral tting to a power-law model was performed by Kruper, Urry & Canizares (1990). The observed 0.2{4.0 keV ux was 7 10 13 erg cm 2 s 1 , corresponding to an unabsorbed isotropic luminosity of 6 10 40 erg s 1 .…”

Section: The Nuclear Regionmentioning

confidence: 99%

ROSAT PSPC and HRI observations of the composite starburst/Seyfert 2 galaxy NGC 1672

Brandt

Halpern

Iwasawa

1996

Monthly Notices of the Royal Astronomical Society

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The nearby barred spiral galaxy NGC 1672 is thought to have a weak Seyfert nucleus in addition to its strong starburst activity. Observations with the Position Sensitive Proportional Counter (PSPC) and High Resolution Imager (HRI) instruments on board the ROSAT X-ray satellite show that three X-ray sources with luminosities (1{ 2) 10 40 erg s 1 are clearly identi ed with NGC 1672. The strongest X-ray source lies at the nucleus, and the other two lie near the ends of the prominent bar, locations that are also bright in H and near-infrared images. The nuclear source is resolved by the HRI on about the scale of the recently identi ed nuclear ring, and one of the sources at the ends of the bar is also probably resolved. The X-ray spectrum of the nuclear source is quite soft, having a Raymond{Smith plasma temperature of 0:7 keV and little evidence for intrinsic absorption. The ROSAT band X-ray ux of the nuclear source appears to be dominated not by X-ray binary emission but rather by di use gas emission. While the properties of the nuclear source are generally supportive of a superbubble interpretation, its large density and emission measure stretch the limits that can be comfortably accommodated by such models. We do not detect direct emission from the putative Seyfert nucleus, although an alternative model for the nuclear source is thermal emission from gas that is photoionized by a hidden Seyfert nucleus. The spectra of the other two X-ray sources are harder than that of the nuclear source, and superbubble models for them have the same strengths and weaknesses.

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Soft X-ray properties of Seyfert galaxies. I - Spectra

Cited by 49 publications

References 0 publications

The recent history of the X-ray absorber in NGC 3516

The recent history of the X-ray absorber in NGC 3516

Resolving the Host Galaxy of the Nearby QSO I Zw 1 with Subarcsecond Multitransition Molecular Line Observations

ROSAT PSPC and HRI observations of the composite starburst/Seyfert 2 galaxy NGC 1672

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