Study of X-ray variability and coronae of Seyfert galaxies using <i>NuSTAR</i>

Rani, Priyanka; Stalin, C. S.; Goswami, K.

doi:10.1093/mnras/stz275

Cited by 26 publications

(41 citation statements)

References 72 publications

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“…We find a more robust lower limit, such that no models meet the p null > 5% criterion below it, at E cut > 250 keV. We are unable to match the data with the spectral parameters listed by Rani et al (2019), who constrained E cut to 70±10 keV based on NuSTAR data alone. A similarly low and tight E cut constraint was found by de Rosa et al (2012) from nonsimultaneous and nonoverlapping XMM-Newton and INTEGRAL data.…”

Section: Limitations and Future Workcontrasting

confidence: 58%

“…Similarly, we find E cut = -+ 550 90 140 keV for Cen A, whereas Fürst et al (2016) concluded that E cut > 1000 keV. Both cases are discussed further in the Appendix, as are the differences for AGNs also studied by Rani et al (2019) and other notably discrepant results. They clearly highlight the importance of acknowledging and quantifying systematics related to the choice of ancillary data and spectral model for any particular E cut measurement even when highquality NuSTAR data are used.…”

Section: Individual Agnssupporting

confidence: 54%

“…Recent work by Molina et al (2019), based on NuSTAR data for the INTEGRAL-selected type1 AGN sample previously studied by the authors, confirmed their earlier results. An independent study of a different sample by Rani et al (2019) claimed a similarly low average E cut . These results pointing to the typical E cut below 150 keV in Sy I samples are apparently inconsistent with our result for the Sy II population.…”

Section: Syi and Mixed Samplesmentioning

confidence: 91%

“…E cut has been well constrained using NuSTAR data in only a handful of obscured AGNs thus far: NGC 4945 (Puccetti et al 2014), MCG -05-23-016 (Baloković et al 2015), ESO 103-G035 (Buisson et al 2018), Mrk 1498 (Ursini et al 2018a), NGC 262, NGC 2992, NGC 7172 (Rani et al 2019), NGC 2110, and NGC 4388 (Ursini et al 2019). Additionally, lower limits on E cut based on NuSTAR data have been derived for obscured sources NGC 5506 (Matt et al 2015), Cyg A (Reynolds et al 2015), Cen A (Fürst et al 2016), PKS 2331-240, and PKS 2356-61 (Ursini et al 2018a).…”

Section: Introductionmentioning

confidence: 99%

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NuSTAR Survey of Obscured Swift/BAT-selected Active Galactic Nuclei. II. Median High-energy Cutoff in Seyfert II Hard X-Ray Spectra

Baloković

Harrison

Madejski

et al. 2020

ApJ

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Broadband X-ray spectroscopy of the X-ray emission produced in the coronae of active galactic nuclei (AGNs) can provide important insights into the physical conditions very close to their central supermassive black holes. The temperature of the Comptonizing plasma that forms the corona is manifested through a high-energy cutoff that has been difficult to directly constrain even in the brightest AGN because it requires high-quality data at energies above 10 keV. In this paper we present a large collection of coronal cutoff constraints for obscured AGNs based on a sample of 130AGNs selected in the hard X-ray band with Swift/BAT and observed nearly simultaneously with NuSTAR and Swift/XRT. We find that under a reasonable set of assumptions regarding partial constraints the median cutoff is well constrained to 290±20 keV, where the uncertainty is statistical and given at the 68% confidence level. We investigate the sensitivity of this result to our assumptions and find that consideration of various known systematic uncertainties robustly places the median cutoff between 240 and 340 keV. The central 68% of the intrinsic cutoff distribution is found to be between about 140 and 500 keV, with estimated uncertainties of 20 and 100 keV, respectively. In comparison with the literature, we find no clear evidence that the cutoffs in obscured and unobscured AGNs are substantially different. Our analysis highlights the importance of carefully considering partial and potentially degenerate constraints on the coronal high-energy cutoff in AGNs.Unified Astronomy Thesaurus concepts: Active galactic nuclei (16); X-ray active galactic nuclei (2035); Seyfert galaxies (1447); High energy astrophysics (739); X-ray surveys (1824)

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Section: Limitations and Future Workcontrasting

confidence: 58%

Section: Individual Agnssupporting

confidence: 54%

Section: Syi and Mixed Samplesmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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NuSTAR Survey of Obscured Swift/BAT-selected Active Galactic Nuclei. II. Median High-energy Cutoff in Seyfert II Hard X-Ray Spectra

Baloković

Harrison

Madejski

et al. 2020

ApJ

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“…Taken from Xie et al (2017). Rani et al (2019); Younes et al (2019). With existing data, we may crudely suggest that LLAGNs have E c 300 − 500 keV.…”

Section: Broadband Sed Of Llagnsmentioning

confidence: 99%

Radiative feedback of low-L_bol/L_Edd AGNs

Xie

2019

Proc. IAU

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AGN feedback, through either radiation or kinematics by expelled medium, plays a crucial role in the coevolution of supermassive black hole (SMBH) and its host galaxy. The nuclei spend most of their time as low-luminosity AGNs (LLAGNs), whose spectra are distinctive to bright AGNs, and the feedback is the hot mode (also named kinetic mode). We thus investigate the radiative heating in the hot mode. We calculate the value of “Compton temperature” Tc, which defines the heating capability of the radiation at given flux, and find that Tc∼(5−15)×107 K, depending on the spectrum of individual LLAGNs. This work provides a cheap way to include the radiative heating of LLAGNs in the study of AGN feedback.

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