Joint ROSAT-Compton GRO observations of the X-ray bright Seyfert galaxy IC 4329A

Madejski, G. M.; Zdziarski, A. A.; Turner, T. J.; Done, Chris; Mushotzky, R. F.; Hartman, R. C.; Gehrels, N.; Connors, A.; Fabian, A. C.; Nandra, K.; Celotti, A.; Rees, M. J.; Johnson, W. N.; Grove, J. E.; Starr, C. H.

doi:10.1086/175111

Cited by 60 publications

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“…The spectrum can be fitted with a power law ( 2 ϭ 40.5/34) with an energy index ␣ ϭ 1.2 H 0.3, and a 50-150 keV photon flux of 13.3 H 1.4 ϫ 10 Ϫ4 photons cm Ϫ2 s Ϫ1 (1.7 H 0.2 ϫ 10 Ϫ10 ergs cm Ϫ2 s Ϫ1 ), making this the second brightest radio-quiet AGN (after NGC 4151) detected by OSSE (see, e.g., Johnson et al 1994; multiply their photon flux by the 0.1 MeV width energy band). This is roughly twice as bright as the brightest Seyfert 1 IC 4329A (Madejski et al 1995) or Seyfert 2's NGC 4507 (Bassani et al 1995) or NGC 4388 (Johnson et al 1994). Including a reflection spectrum (the model ''pexrav'' in XSPEC: Magdziarz & Zdziarski 1995) fixed to the amount expected from an isotropic source illuminating a flat slab of solar abundance material inclined at 60Њ to the observer gives little change in the quality of the fit 2 ϭ 40.8/33, with ␣ ϭ 1.05 Ϫ0.25 ϩ0.3 .…”

Section: Ossementioning

confidence: 88%

NGC 4945: The Brightest Seyfert 2 Galaxy at 100 keV

Done

Madejski

Smith

1996

The Astrophysical Journal

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Seyfert 2 galaxies are generally heavily absorbed in soft X-rays, plausibly because of obscuration of the Seyfert nucleus by a thick molecular torus. With a high torus column, 10 23 Ն N H Ն 10 25 cm Ϫ2 , the observed flux in the ''classical'' 2-10 keV X-ray band can be strongly suppressed, while at higher energies the photoelectric absorption becomes less important and the true nuclear luminosity can be seen. The high-energy bandpass of the Ginga X-ray telescope, extending to 20 keV, allowed several such objects to be discovered, and an extrapolation of the obscured nuclear spectra out to 100 keV suggested that NGC 4945 should be among the very brightest radio-quiet Seyferts in the sky at 100 keV, second only to NGC 4151. OSSE data reported here confirm this prediction, and we analyze these, together with archival Ginga and ASCA data, in order to present a broadband spectrum from 0.6 -500 keV of this object.

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Section: Ossementioning

confidence: 88%

NGC 4945: The Brightest Seyfert 2 Galaxy at 100 keV

Done

Madejski

Smith

1996

The Astrophysical Journal

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“…A significant fraction of type 1 active galactic nuclei (Reynolds 1997) also show K-shells absorption edges of warm oxygen (O VII and O VIII) characteristic of optically thin, photoionized material along the line of sight to the central engine, the so-called warm absorber. In the soft energy spectrum of IC 4329A, Madejski et al (1995) discovered with ROSAT the existence either of a ionized edge imprinted by a warm absorber, or of a soft excess.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous XMM-Newton and BeppoSAX observation of the Seyfert I galaxy IC 4329A

Gondoin

Barr

Lumb

et al. 2001

A&A

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Abstract. We report on a simultaneous XMM-Newton and BeppoSAX observation of the Seyfert 1 galaxy IC 4329A performed in 2001 January. Above 1 keV, EPIC spectra show a narrow Fe K emission line at 6.42 +0.04−0.03 keV with an equivalent width of 43 ± 1 eV. An absorption edge is detected at 7.1± 0.4 keV in the source rest frame that has not been reported before. The energy of these features is consistent with reflection of the primary X-ray continuum by a optically thick material containing iron in low states of ionization. The narrow Fe K feature suggests that the reflection arises relatively far from a putative central black hole. Spectral fitting of simultaneous XMM-Newton and BeppoSAX data over the 0.3-130 keV energy range shows that the primary continuum is well described by a cut-off power law with a photon index of 1.93 ± 0.03 and a folding energy of 260 ± 130 keV. The high energy tail >10 keV constrains the reflection fraction close to unity. Fitting over the overall spectral range indicates that the Fe abundance within the cool reflecting material is not significantly different from the cosmic value. The extrapolation of the primary power law continuum to energies <1 keV indicates the presence of absorption edges produced by neutral and ionized oxygen. The optical depth of the O I edge at 0.54 keV constrains the intrinsic absorption by neutral material to an hydrogen column density of = (33 ± 3) × 10 20 cm −2 along the line of sight to IC 4329A nucleus. The energy of the edge at 0.854 ± 0.009 keV is consistent with absorption by O VIII. A third edge at 0.660 ± 0.008 keV is likely related to absorption by O VI and N VII. The simultaneous presence of O VI and O VIII edges without significant O VII absorption indicates that the warm absorber originates from at least two zones.

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“…Sunyaev & Titarchuk 1980). Such models fit the Xray spectrum extremely well (Haardt & Maraschi 1991, particularly if the corona is patchy (Haardt, Maraschi & Ghisellini 1994;Stern et al 1995) and the particle distribution has a thermal form (Zdziarski et al 1994;Madejski et al 1995;Gondek et al 1996). The coronal heating mechanism is not known, but some possibilities are that a portion of the accretion flow is intrinsically hot (e.g.…”

Section: Introductionmentioning

confidence: 99%