The soft X-ray/NLR connection: a single photoionized medium?

Bianchi, S.; Guainazzi, M.; Chiaberge, M.

doi:10.1051/0004-6361:20054091

Cited by 253 publications

(388 citation statements)

References 57 publications

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“…However, formal fits with a photoelectrically absorbed apec component to the two spectra confirms only marginally this hint (Table 4). Only ∼ < 10% of the total soft Xray emission is associated in this galaxy to the unresolved nucleus, by contrast to what typically observed on AGN-dominated Seyfert 2 galaxies (Bianchi et al 2006). …”

Section: Comparison With the Chandra Resultscontrasting

confidence: 67%

AGN/starburst connection in action: the half million second RGS spectrum of NGC 1365

Guainazzi¹,

Risaliti

Nucita³

et al. 2009

A&A

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Context. High-resolution X-ray observations in the imaging and spectral domain have recently opened a new window on active galactic nuclei (AGN) feedback onto the circumnuclear gas. Spectral diagnostics, as well as the remarkable morphological coincidence between [O iii] and X-rays, point to AGN photoionisation as the dominant ionisation mechanism on scales as large as a few kpc.Aims. In this paper we extend these studies to the nearby Seyfert 2 galaxy NGC 1365, known to host a circumnuclear ring of intense star formation at 1.3 kpc from the nucleus. The main scope of this investigation is to study the connection between nuclear activity and star formation in nearby AGN. Methods. We present a deep ( 5.8 days) 0.3-2 keV high-resolution spectrum of NGC 1365, collected with the reflection grating spectrometer (RGS) on board XMM-Newton. Results. The spectrum is dominated by strong recombination lines of He-and H-like transitions from carbon to silicon, as well as by L transitions from Fexvii. The continuum is strong, especially in the 10 to 20 Å range. Formal fits require two optically thin, collisionally ionised plasma components, with temperatures 300 and 640 eV. However, they leave the bulk of the forbidden components of the He-α Ovii and Nvi triplets unaccounted for. These features can be explained as being produced by photoionised gas. NGC 1365 is therefore the first obscured AGN, whose high-resolution X-ray spectrum requires both collisional ionisation and photoionisation. Conclusions. The relative weakness of photoionisation does not stem from the intrinsic weakness of its AGN, whose X-ray luminosity is ∼ > 10 42 erg s −1 . We suggest that it may instead come from the line-of-sight from the active nucleus to the NLR being blocked by optically thick matter in the broad line region, at the same time responsible for the large observed variation of the column density obscuring the X-ray active nucleus. Alternatively, NGC 1365 could host a remarkably luminous nuclear starburst when compared to the AGN accretion power.

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Section: Comparison With the Chandra Resultscontrasting

confidence: 67%

AGN/starburst connection in action: the half million second RGS spectrum of NGC 1365

Guainazzi¹,

Risaliti

Nucita³

et al. 2009

A&A

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“…The AGN is known to be heavily absorbed and characterized by a large iron emission feature, probably associated with Compton reflection of hard photons (e.g. Guainazzi et al 2004;Bianchi et al 2006;Annuar et al 2015). Other emission features have also been found in the XMM-Newton spectra of the AGN, and these have been associated with photoionized emission regions.…”

Section: A P P E N D I X a : S P E C T R A L A Na Ly S I S O F T H E mentioning

confidence: 99%

“…We make use of the high-quality data from this XMM-Newton observation (∼100 ks) to test whether we can rule out either sub-or super-Eddington accretion in NGC 5643 ULX1. Besides the ULX, NGC 5643 hosts also an AGN (Guainazzi et al 2004;Bianchi, Guainazzi & Chiaberge 2006;Annuar et al 2015). Results of the spectral analysis of the AGN are also briefly reported in and discussed in Appendix A.…”

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confidence: 99%

The ultraluminous X-ray source NGC 5643 ULX1: a large stellar mass black hole accreting at super-Eddington rates?

Pintore

Zampieri

Sutton

et al. 2016

Mon. Not. R. Astron. Soc.

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A sub-set of the brightest ultraluminous X-ray sources (ULXs), with X-ray luminosities well above 10 40 erg s −1 , typically have energy spectra which can be well described as hard power-laws, and short-term variability in excess of ∼ 10%. This combination of properties suggests that these ULXs may be some of the best candidates to host intermediate mass black holes (IMBHs), which would be accreting at sub-Eddington rates in the hard state seen in Galactic X-ray binaries. In this work, we present a temporal and spectral analysis of all of the available XMM-Newton data from one such ULX, the previously poorly studied 2XMM J143242.1−440939, located in NGC 5643. We report that its high quality EPIC spectra can be better described by a broad, thermal component, such as an advection dominated disc or an optically thick Comptonising corona. In addition, we find a hint of a marginal change in the short-term variability which does not appear to be clearly related to the source unabsorbed luminosity. We discuss the implications of these results, excluding the possibility that the source may be host an IMBH in a low state, and favouring an interpretation in terms of super-Eddington accretion on to a black hole of stellar origin. The properties of NGC 5643 ULX1 allow us to associate this source to the population of the hard/ultraluminous ULX class.

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“…8) or in obscured Seyfert type-2 galaxies (see, e.g., Bianchi et al 2006). This region is also supposed to be responsible for the measured polarisation degree that is unusually high for a type-1 object (Schmid et al 2001).…”

Section: Scattering Regionmentioning

confidence: 99%

An X-ray variable absorber within the broad line region in Fairall 51

Svoboda

Guainazzi

Longinotti

et al. 2015

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Context. Fairall 51 is a polar-scattered Seyfert 1 galaxy, a type of active galaxy believed to represent a bridge between unobscured type-1 and obscured type-2 objects. Fairall 51 has shown complex and variable X-ray absorption, but little is known about its origin. Aims. In our research, we observed Fairall 51 with the X-ray satellite Suzaku in order to constrain a characteristic time scale of its variability. Methods. We performed timing and spectral analysis of four observations separated by 1.5, 2, and 5.5 day intervals. Results. We found that the 0.5-50 keV broadband X-ray spectra are dominated by a primary power-law emission (with the photon index ∼2). This emission is affected by at least three absorbers with different ionisations (log ξ ≈ 1-4). The spectrum is shaped further by a reprocessed emission, possibly coming from two regions, the accretion disc and a more distant scattering region. The accretion disc emission is smeared by the relativistic effects, from which we measured the spin of the black hole as a ≈ 0.8 ± 0.2. We found that most of the spectral variability can be attributed to the least ionised absorber whose column density changed by a factor of two between the first (highest-flux) and the last (lowest-flux) observation. Conclusions. A week-long scale of the variability indicates that the absorber is located at the distance ≈0.05 pc from the centre, i.e., in the broad line region.

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The soft X-ray/NLR connection: a single photoionized medium?

Cited by 253 publications

References 57 publications

AGN/starburst connection in action: the half million second RGS spectrum of NGC 1365

AGN/starburst connection in action: the half million second RGS spectrum of NGC 1365

The ultraluminous X-ray source NGC 5643 ULX1: a large stellar mass black hole accreting at super-Eddington rates?

An X-ray variable absorber within the broad line region in Fairall 51

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