The highly variable X-ray spectrum of the luminous Seyfert 1 galaxy 1H 0419-577

Page, K. L.; Pounds, K. A.; Reeves, J. N.; O’Brien, P. T.

doi:10.1046/j.1365-8711.2002.05184.x

Cited by 27 publications

(36 citation statements)

References 23 publications

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“…With the increased bandwidth and sensitivity of present instrumentation, this feature appears to be present in other Seyfert 1 galaxies (e.g., 1H 0419-577, Page et al 2002;NGC 3783, De Rosa et al 2002;MCG-6-30-15, Vaughan & Edelson 2001;NGC 5548, Petrucci et al 2000;Nicastro et al 2000;NGC 7469, Nandra et al 2000; IC 4329A, Done et al 2000;Mkn 509, De Rosa et al 2004;Zdziarski et al 2003). In summary, in the broad X-ray range from 0.1 to 200 keV, NGC 4151 represents a case study of the common properties (absorption/scattering medium) of type 1 and type 2 objects, of AGN environment from light-day to kpc, and of investigation of the properties of the intrinsic continuum.…”

Section: Introductionmentioning

confidence: 81%

The broad band spectrum and variability of NGC 4151 observed by BeppoSAX

Rosa¹,

Piro²,

Perola

et al. 2006

A&A

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We present an analysis of all BeppoSAX observations of NGC 4151. This source was observed 5 times from 1996 to 2001 with durations ranging from a day to four days. The intrinsic continuum (described as a cut-off power law) is absorbed at low energies by a complex system: a cold patchy absorber plus a warm uniform screen photoionised by the central continuum. We find that this "dual absorber" is the main driver of the observed variability, up to a factor of eight, at 3 keV. In particular the covering fraction of the cold absorber changes on time scales of the order of a day, supporting its association with the broad-line region. The column density of the warm gas varies on a longer time scale (months to year). Some of the small amplitude spectral variability above 10 keV can be explained with an intrinsic variation (with variation of the photon index ∆Γ ∼ 0.2). The flux below 1 keV remains constant confirming an extended origin. Its spectrum is reproduced by a combination of a thermal component (with temperature kT = 0.15 keV) and a power law with the same slope as the intrinsic continuum, but with an intensity of a few percent. A Compton reflection component is significantly detected in 1996 (averaged value of Ω/2π ∼ 0.4, with the solid angle Ω covered by the reflecting medium), with intensity decreasing on a time scale of a year, and it desappears in 2000 and 2001. The long time scale of variations argues for an association with an optically thick torus at a distance of a few light years. An iron line was detected in all spectra. Its energy is consistent with fluorescence by cold iron. We find that the line is variable. Its behaviour is reproduced by a variable component proportional to the level of the reflection flux plus a constant component. The flux of the latter is consistent with the extended line emission observed by Chandra. We conclude that the first component likely arises from the torus and the second is produced in the extended narrow-line region.

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Section: Introductionmentioning

confidence: 81%

The broad band spectrum and variability of NGC 4151 observed by BeppoSAX

Rosa¹,

Piro²,

Perola

et al. 2006

A&A

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“…According to Page et al (2002), the cooling of the plasma temperature in the hot corona may produce the observed flux/spectral transition. Afterwards, Pounds et al (2004a,b) carried on a systematic study of the spectral variability in this source, using five ∼15 ks long observations, which had been taken during one year with a time spacing of ∼3 months.…”

Section: H 0419-577: a Variable Seyfert Galaxymentioning

confidence: 99%

SimultaneousXMM-Newtonand HST-COS observation of 1H 0419–577

Gesu

Costantini

Piconcelli

et al. 2014

A&A

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In this paper, we present the longest exposed (97 ks) XMM-Newton EPIC-pn spectrum ever obtained for the Seyfert 1.5 galaxy 1H 0419-577. With the aim of explaining the broadband emission of this source, we took advantage of the simultaneous coverage in the optical/UV that was provided in the present case by the XMM-Newton Optical Monitor and by a HST-COS observation. Archival FUSE flux measurements in the far-ultraviolet were also used for the present analysis. We successfully modeled the X-ray spectrum and the optical/UV fluxes data points using a Comptonization model. We found that a blackbody temperature of T ∼ 56 eV accounts for the optical/UV emission originating in the accretion disk. This temperature serves as an input for the Comptonized components that model the X-ray continuum. Both a warm (T wc ∼ 0.7 keV, τ wc ∼ 7) and a hot corona (T hc ∼ 160 keV, τ hc ∼ 0.5) intervene to upscatter the disk photons to X-ray wavelengths. With the addition of a partially covering (C v ∼ 50%) cold absorber with a variable opacity ( N H ∼ [10 19 −10 22 ] cm −2 ), this model can also explain the historical spectral variability of this source, with the present dataset presenting the lowest one ( N H ∼ 10 19 cm −2 ). We discuss a scenario where the variable absorber becomes less opaque in the highest flux states because it gets ionized in response to the variations of the X-ray continuum. The lower limit for the absorber density derived in this scenario is typical for the broad line region clouds. We infer that 1H 0419-577 may be viewed from an intermediate inclination angle i ≥ 54 • , and, on this basis, we speculate that the X-ray obscuration may be associated with the innermost dust-free region of the obscuring torus. Finally, we critically compare this scenario with all the different models (e.g., disk reflection) that have been used in the past to explain the variability of this source.

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“…Such a difference in continuum at soft energies is often observed in Seyfert galaxies as a "soft excess", empirically modelled with one or more black-body components (e.g. Page et al 2002) Table 1. Best-fit parameters and 68% confidence limits for various fits to the combined EPIC data.…”

Section: X-ray Spectramentioning

confidence: 99%

XMM-Newton observations of the BL Lac MS 0205.7+3509: A dense, low-metallicity absorber

Watson

McBreen

Hanlon

et al. 2004

A&A

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Abstract. The high-frequency-peaked BL Lac, MS 0205.7+3509 was observed twice with XMM-Newton. Both X-ray spectra are synchrotron-dominated, with mean 0.2-10 keV fluxes of 2.80 ± 0.01 and 3.34 ± 0.02 × 10 −12 erg cm −2 s −1 . The X-ray spectra are well fit by a power-law with absorption above the Galactic value, however no absorption edges are detected, implying a low metallicity absorber (Z = 0.04 +0.03 −0.01 ) or an absorber with redshift above one (best-fit z = 2.1 for an absorber with solar abundances). In either case the absorbing column density must be ∼9 × 10 21 cm −2 . A new optical spectrum is presented, with aMg  absorption doublet detected at z = 0.351, but no other significant features. The optical spectrum shows little reddening, implying a low dust to gas ratio in the absorber. MS 0205.7+3509 must therefore be viewed through a high column density, low-metallicity gas cloud, probably at z = 0.351 and associated with the galaxy that has been shown to be within ∼2 of the BL Lac.

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The highly variable X-ray spectrum of the luminous Seyfert 1 galaxy 1H 0419-577

Cited by 27 publications

References 23 publications

The broad band spectrum and variability of NGC 4151 observed by BeppoSAX

The broad band spectrum and variability of NGC 4151 observed by BeppoSAX

SimultaneousXMM-Newtonand HST-COS observation of 1H 0419–577

XMM-Newton observations of the BL Lac MS 0205.7+3509: A dense, low-metallicity absorber

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