Sustaining a warm corona in active galactic nucleus accretion discs

Ballantyne, D. R.; Xiang, Xin

doi:10.1093/mnras/staa1866

Cited by 24 publications

(19 citation statements)

References 51 publications

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“…However, through recent radiative transfer computation in hydrostatic and radiative equilibrium, Gronkiewicz & Różańska (2020) has shown that for lower accretion rates, thermal instability should prevent the warm corona from forming. The low accretion rate system is unable to provide enough energy to sustain a warm corona (Ballantyne & Xiang 2020). It is therefore unclear whether a strong warm corona can be sustained at the low accretion rates relevant here ( m 0.015).…”

Section: Physical Properties Of the Warm Corona Modelmentioning

confidence: 90%

The Nature of Soft Excess in ESO 362-G18 Revealed by XMM-Newton and NuSTAR Spectroscopy

García

Walton

et al. 2021

ApJ

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We present a detailed spectral analysis of the joint XMM-Newton and NuSTAR observations of the active galactic nuclei (AGNs) in the Seyfert 1.5 Galaxy ESO 362-G18. The broadband (0.3-79 keV) spectrum shows the presence of a power-law continuum with a soft excess below 2 keV, iron Kα emission (∼6.4 keV), and a Compton hump (peaking at ∼20 keV). We find that the soft excess can be modeled by two different possible scenarios: a warm (kT e ∼ 0.2 keV) and optically thick (τ ∼ 34) Comptonizing corona, or with a relativistically blurred reflection off a high-density ( [ ]>n log cm 18.3 e 3) inner disk. These two models cannot be easily distinguished solely from their fit statistics. However, the low temperature (kT e ∼ 20 keV) and the thick optical depth (τ ∼ 5) of the hot corona required by the warm corona scenario are uncommon for AGNs. We also fit a "hybrid" model, which includes both disk reflection and a warm corona. Unsurprisingly, as this is the most complex of the models considered, this provides the best fit, and more reasonable coronal parameters. In this case, the majority of the soft excess flux arises in the warm corona component. However, based on recent simulations of warm coronae, it is not clear whether such a structure can really exist at the low accretion rates relevant for ESO 362-G18 ( m 0.015). This may therefore argue in favor of a scenario in which the soft excess is instead dominated by the relativistic reflection. Based on this model, we find that the data would require a compact hot corona (h ∼ 3 R Horizon ) around a rapidly spinning (a å > 0.927) black hole.Unified Astronomy Thesaurus concepts: Supermassive black holes (1663); X-ray astronomy (1810); Seyfert galaxies (1447); High energy astrophysics (739); Active galactic nuclei (16); Astrophysical black holes (98); Spectroscopy (1558); X-ray active galactic nuclei (2035)

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Section: Physical Properties Of the Warm Corona Modelmentioning

confidence: 90%

The Nature of Soft Excess in ESO 362-G18 Revealed by XMM-Newton and NuSTAR Spectroscopy

García

Walton

et al. 2021

ApJ

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“…They are also consistent with those measured (kT warm ∼0.3-1 keV, τ warm ∼10-20) in XMM-Newton AGN samples (e.g., Porquet et al 2004;Bianchi et al 2009), and in several individual X-ray broad-band spectral analysis of AGN, such as: Mrk 509 (Petrucci et al 2013;Mehdipour et al 2015), Ark 120 (Matt et al 2014;Porquet et al 2018), HE 1143-1810(Ursini et al 2020, NGC 4593 (Middei et al 2019), Mrk 359 (Middei et al 2020), TON S180 (Matzeu et al 2020), and ESO 511-G030 (Ghosh & Laha 2021). Very recent state-of-the-art simulations have been performed showing that a warm corona with such properties can indeed exist, until sufficient internal mechanical heating is present, and that warm and hot coronae can co-exist (Petrucci et al 2018(Petrucci et al , 2020Ballantyne 2020;Ballantyne & Xiang 2020). Moreover, these authors found that no strong absorption/emission lines are formed which can well explain the absorption-free smooth soft X-ray shape observed in bare AGN, or in most other AGN when the warm absorber and any moderate relativistic reflection contributions have been removed.…”

Section: Summary and Discussionmentioning

confidence: 99%

The first simultaneous X-ray broad-band view of Mrk 110 with XMM-Newton and NuSTAR

Porquet,

Reeves,

Grosso

et al. 2021

Preprint

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Context. Soft and hard X-ray excesses, compared to the continuum power-law shape between ∼2-10 keV, are common features observed in the spectra of active galactic nuclei (AGN) and are associated with the accretion disc-corona system around the supermassive black hole. However, the dominant process at work is still highly debated and has been proposed to be either relativistic reflection or Comptonisation. Such an investigation can be problematic for AGN having significant intrinsic absorption, either cold or warm, which can severely distort the observed continuum. Therefore, AGN with no (or very weak) intrinsic absorption along the line of sight, called bare AGN, are the best targets to directly probe disc-corona systems. Aims. We aim to characterise the main X-ray spectral physical components from the bright bare Broad Line Seyfert 1 AGN Mrk 110, and the physical process(es) at work in its disc-corona system viewed almost face-on. Methods. We perform the X-ray broad-band spectral analysis thanks to two simultaneous XMM-Newton and NuSTAR observations performed on November 16-17 2019 and April 5-6 2020, we also use for the spectral analysis above 3 keV the deep NuSTAR observation obtained in January 2017.Results. The broad-band X-ray spectra of Mrk 110 are characterised by the presence of a prominent and absorption-free smooth soft X-ray excess, moderately broad O vii and Fe Kα emission lines and a lack of a strong Compton hump. The continuum above ∼3 keV is very similar at both epochs, while some variability (stronger when brighter) is present for the soft X-ray excess. A combination of soft and hard Comptonisation by a warm and hot corona, respectively, plus mildly relativistic disc reflection reproduce the broadband X-ray continuum very well. The inferred warm corona temperature, kT warm ∼0.3 keV, is similar to the values found in other sub-Eddington AGN, whereas the hot corona temperature, kT hot ∼ 21-31 keV (depending mainly on the assumed hot corona geometry), is found to be in the lower range of the values measured in AGN.

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“…Porquet et al 2004;Bianchi et al 2009) and in several individual X-ray broadband spectral analyses of AGN, such as: Mrk 509 (Petrucci et al 2013;Mehdipour et al 2015), Ark 120 (Matt et al 2014;Porquet et al 2018), HE 1143−1810 (Ursini et al 2020), NGC 4593 (Middei et al 2019), Mrk 359 (Middei et al 2020), TON S180 (Matzeu et al 2020), and ESO 511-G030 (Ghosh & Laha 2021). Very recent state-of-the-art simulations have been performed that show that a warm corona with such properties can indeed exist, until sufficient internal mechanical heating is present, and that warm and hot coronae can co-exist (Petrucci et al 2018(Petrucci et al , 2020Ballantyne 2020;Ballantyne & Xiang 2020). Moreover, these authors found that neither strong absorption nor emission lines are formed, which can explain the absorption-free smooth soft X-ray shape observed in bare AGN or in most other AGN when the warm absorber and any moderate relativistic reflection contributions have been removed.…”

Section: Summary and Discussionmentioning

confidence: 99%

The first simultaneous X-ray broadband view of Mrk 110 with XMM-Newton and NuSTAR

Porquet

Reeves

Grosso

et al. 2021

A&A

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Context. Soft and hard X-ray excesses, compared to the continuum power-law shape between ∼2−10 keV, are common features observed in the spectra of active galactic nuclei (AGN) and are associated with the accretion disc-corona system around the supermassive black hole. However, the dominant process at work is still highly debated and has been proposed to be either relativistic reflection or Comptonisation. Such an investigation can be problematic for AGN that have significant intrinsic absorption, either cold or warm, which can severely distort the observed continuum. Therefore, AGN with no (or very weak) intrinsic absorption along the line-of-sight, called bare AGN, are the best targets for directly probing disc-corona systems. Aims. We aim to characterise the main X-ray spectral physical components from the bright bare broad-line Seyfert 1 AGN Mrk 110, as well as the physical process(es) at work in its disc-corona system viewed almost face-on. Methods. We perform the X-ray broadband spectral analysis thanks to two simultaneous XMM-Newton and NuSTAR observations performed on November 16−17, 2019, and April 5−6, 2020. We also use a deep NuSTAR observation obtained in January 2017 for the spectral analysis above 3 keV. Results. The broadband X-ray spectra of Mrk 110 are characterised by the presence of a prominent and absorption-free smooth soft X-ray excess, moderately broad O VII and Fe Kα emission lines, and a lack of a strong Compton hump. The continuum above ∼3 keV is very similar at both epochs, while some variability (stronger when brighter) is present for the soft X-ray excess. A combination of soft and hard Comptonisation by a warm and hot corona, respectively, plus mildly relativistic disc reflection reproduce the broadband X-ray continuum very well. The inferred warm corona temperature, kTwarm ∼ 0.3 keV, is similar to the values found in other sub-Eddington AGN, whereas the hot corona temperature, kThot ∼ 21−31 keV (depending mainly on the assumed hot corona geometry), is found to be in the lower range of the values measured in AGN.

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Sustaining a warm corona in active galactic nucleus accretion discs

Cited by 24 publications

References 51 publications

The Nature of Soft Excess in ESO 362-G18 Revealed by XMM-Newton and NuSTAR Spectroscopy

The Nature of Soft Excess in ESO 362-G18 Revealed by XMM-Newton and NuSTAR Spectroscopy

The first simultaneous X-ray broad-band view of Mrk 110 with XMM-Newton and NuSTAR

The first simultaneous X-ray broadband view of Mrk 110 with XMM-Newton and NuSTAR

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