The Oriented Scintillation Spectrometer Experiment - Instrument description

Johnson, W. N.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.; Purcell, W. R.; Grabelsky, D. A.; Ulmer, M. P.; Hillis, D. A.; Jung, G. V.; Cameron, R. A.

doi:10.1086/191795

Cited by 163 publications

(88 citation statements)

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“…This explains also larger spectral slope values fitted to the ISGRI spectra, when compared with the values quoted by Dadina (2007), although the primary reason for the these differences is the simpler spectral model applied to the INTEGRAL data. CGRO/OSSE (Johnson et al 1993) covered the energy range of approximately 50−10 3 keV. It therefore primariliy detected AGN with hard and bright X-ray spectra, which we also expect to be detectable by INTEGRAL.…”

Section: The Sample In Comparison With Previous Studiesmentioning

confidence: 83%

The second INTEGRAL AGN catalogue

Beckmann

Soldi

Ricci

et al. 2009

A&A

167

204

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Aims. The INTEGRAL mission provides a large data set for studying the hard X-ray properties of AGN and allows testing of the unified scheme for AGN.Methods. We present analysis of INTEGRAL IBIS/ISGRI, JEM-X, and OMC data for 199 AGN supposedly detected by INTEGRAL above 20 keV. Results. The data analysed here allow significant spectral extraction on 148 objects and an optical variability study of 57 AGN. The slopes of the hard X-ray spectra of Seyfert 1 and Seyfert 2 galaxies are found to be consistent within the uncertainties, whereas higher cut-off energies and lower luminosities we measured for the more absorbed/type 2 AGN. The intermediate Seyfert 1.5 objects exhibit hard X-ray spectra consistent with those of Seyfert 1. When applying a Compton reflection model, the underlying continua appear the same in Seyfert 1 and 2 with Γ 2, and the reflection strength is about R 1, when assuming different inclination angles. A significant correlation is found between the hard X-ray and optical luminosity and the mass of the central black hole in the sense that the more luminous objects appear to be more massive. There is also a general trend toward the absorbed sources and type 2 AGN having lower Eddington ratios. The black hole mass appears to form a fundamental plane together with the optical and X-ray luminosity of the form L V ∝ L 0.6 X M 0.2 BH , similar to what is found between L R , L X , and M BH . Conclusions. The transition from the type 1 to type 2 AGN appears to be smooth. The type 2 AGN are less luminous and have less accreting super massive black holes. The unified model for Seyfert galaxies seems to hold, showing in hard X-rays that the central engine is the same in Seyfert 1 and 2, but seen under different inclination angles and absorption. The fundamental plane links the accretion mechanism with the bulge of the host galaxy and with the mass of the central engine in the same way in all types of Seyfert galaxies.

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Section: The Sample In Comparison With Previous Studiesmentioning

confidence: 83%

The second INTEGRAL AGN catalogue

Beckmann

Soldi

Ricci

et al. 2009

A&A

167

204

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“…In this work, we present two, very similar, broad-band X-ray/γ-ray (hereafter Xγ) spectra of GX 339-4 obtained during a strong outburst of the source in September 1991 (Harmon et al 1994) simultaneously by Ginga (Makino et al 1987) and the Oriented Scintillation Spectroscopy Ex-periment (OSSE) detector (Johnson et al 1993) on board the Compton Gamma Ray Observatory (CGRO). The source was in the hard (also called 'low') spectral state.…”

Section: Introductionmentioning

confidence: 99%

Broad-band X-ray/γ-ray spectra and binary parameters of GX 339–4 and their astrophysical implications

Zdziarski¹,

Poutanen²,

Mikołajewska³

et al. 1998

Monthly Notices of the Royal Astronomical Society

198

217

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We present X-ray/γ-ray spectra of the binary GX 339-4 observed in the hard state simultaneously by Ginga and CGRO OSSE during an outburst in 1991 September. The Ginga X-ray spectra are well represented by a power law with a photon spectral index of Γ ≃ 1.75 and a Compton reflection component with a fluorescent Fe Kα line corresponding to a solid angle of an optically-thick, ionized, medium of ∼ 0.4×2π. The OSSE data ( 50 keV) require a sharp high-energy cutoff in the power-law spectrum. The broad-band spectra are very well modelled by repeated Compton scattering in a thermal plasma with an optical depth of τ ∼ 1 and kT ≃ 50 keV. We also study the distance to the system and find it to be > ∼ 3 kpc, ruling out earlier determinations of ∼ 1 kpc. Using this limit, the observed reddening and the orbital period, we find the allowed range of the mass of the primary is consistent with it being a black hole.We find the data are incosistent with models of either homogenous or patchy coronae above the surface of an accretion disc. Rather, they are consistent with the presence of a hot inner hot disc with the viscosity parameter of α ∼ 1 accreting at a rate close to the maximum set by advection. The hot disc is surrounded by a cold outer disc, which gives rise to the reflection component and a soft X-ray excess, also present in the data. The seed photons for Comptonization are unlikely to be due to thermal synchrotron radiation. Rather, they are supplied by the outer cold disc and/or cold clouds within the hot disc. e ± pair production is negligible if electrons are thermal. The hot disc model, which scaled parameters are independent of the blackhole mass, is supported by the similarity of the spectrum of GX 339-4 to those of other black-hole binaries and Seyfert 1s. On the other hand, their spectra in the soft γ-ray regime are significantly harder than those of weakly-magnetized neutron stars. Based on this difference, we propose that the presence of broad-band spectra corresponding to thermal Comptonization with kT > ∼ 50 keV represents a black-hole signature.

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“…However, the form of a Lubinski, high-energy cuto † of the power law remains poorly constrained. In the case of the brightest radio-quiet Seyfert galaxy, NGC 4151, results from the Oriented Scintillation Spectroscopy Experiment (OSSE ; Johnson et al 1993) aboard Compton Gamma Ray Observatory show the spectrum above 50 keV is well described by thermal Comptonization (e.g., Johnson et al 1997a, hereafter J97). However, the X-ray spectrum of NGC 4151 is heavily absorbed, and it is not clear whether its intrinsic spectrum is typical for Seyfert galaxies.…”

Section: Introductionmentioning

confidence: 99%

Observations of Seyfert Galaxies by OSSE and Parameters of Their X‐Ray/Gamma‐Ray Sources

Zdziarski

Poutanen

Johnson

2000

ApJ

138

117

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We present a summary of spectra of Seyfert galaxies observed by the OSSE detector aboard Compton Gamma Ray Observatory. We obtain average spectra of Seyfert galaxies of types 1 and 2 and Ðnd they are well Ðtted by thermal Comptonization. We present detailed parameter ranges for the plasma temperature and the Compton parameter in the cases of spherical and slab geometries. We Ðnd both the average and individual OSSE spectra of Seyfert 2s are signiÐcantly harder than those of Seyfert 1s, which di †erence can be due to anisotropy of Compton reÑection and/or Thomson-thick absorption.

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The Oriented Scintillation Spectrometer Experiment - Instrument description

Cited by 163 publications

References 0 publications

The second INTEGRAL AGN catalogue

The second INTEGRAL AGN catalogue

Broad-band X-ray/γ-ray spectra and binary parameters of GX 339–4 and their astrophysical implications

Observations of Seyfert Galaxies by OSSE and Parameters of Their X‐Ray/Gamma‐Ray Sources

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