X-ray Coronal Properties of Swift/BAT-Selected Seyfert 1 Active Galactic Nuclei

Kamraj, Nikita; Brightman, Murray; Harrison, Fiona A.; Stern, Daniel; García, Javier A.; Baloković, Mislav; Ricci, Claudio; Koss, Michael J.; Mejía-Restrepo, Julian E.; Oh, Kyuseok; Powell, Meredith C.; Urry, C. Megan

doi:10.48550/arxiv.2202.00895

Cited by 3 publications

(6 citation statements)

References 62 publications

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“…However, we find no significant correlation between λ edd and Γ, or between λ edd and E cut in our sample (see Fig. 7), consistent with the results of Molina et al (2019), Hinkle & Mushotzky (2021) and Kamraj et al (2022). This is likely because the uncertainties in the measurements of λ edd are large, or the E cut -Γ correlation we find is not driven by Ed-dington ratio.…”

Section: The Underlying Mechanismssupporting

confidence: 79%

“…6 in Fabian et al 2017). On the other hand, both the directly measured and conservatively estimated T e (1/3 E cut here, while 1/2 in Fabian et al 2015) of a considerable fraction of sources lie beyond (to the right of) the slab pair line, consistent with Kamraj et al (2022), favoring the sphere or hemisphere geometry. Considering the E cut -Γ relation shown above, it is implied that the coronal geometry might be spectral slope dependent, i.e., flatter shape for harder spectra, and rounder for softer spectra.…”

Section: The Underlying Mechanismssupporting

confidence: 53%

“…The Nuclear Spectroscopic Telescope Array (NuSTAR; Harrison et al 2013) is the first hard X-ray telescope with direct-imaging capability above 10 keV. With its broad spectral coverage of 3-78 keV, NuSTAR has enabled the measurements (or lower limits) of E cut /kT e in a number of AGNs (e.g., Ballantyne et al 2014;Matt et al 2015;Ursini et al 2016;Kamraj et al 2018;Tortosa et al 2018;Molina et al 2019;Rani et al 2019;Panagiotou & Walter 2020;Porquet et al 2021;Hinkle & Mushotzky 2021;Akylas & Georgantopoulos 2021;Kamraj et al 2022). Meanwhile, variations of E cut /T e are also reported in a few individual sources (e.g., Keek & Ballantyne 2016;Zhang et al 2018;Kang et al 2021).…”

Section: Introductionmentioning

confidence: 99%

“…In many sample studies, only poorly constrained lower limits could be obtained for the dominant fraction of sources in the samples (e.g. Ricci et al 2018;Kamraj et al 2018;Panagiotou & Walter 2020;Kamraj et al 2022), hindering further reliable statistical studies, e.g., to probe the dependence of E cut /kT e on other physical parameters. Meanwhile, the E cut measurements are often sensitive to the choice of spectral models.…”

Section: Introductionmentioning

confidence: 99%

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The X-ray coronae in NuSTAR bright active galactic nuclei

Kang,

Wang

2022

Preprint

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We present systematic and uniform analysis of NuSTAR data with 10-78 keV S/N > 50, of a sample of 60 SWIFT BAT selected AGNs, 10 of which are radio-loud. We measure their high energy cutoff E cut or coronal temperature T e using three different spectral models to fit their NuSTAR spectra, and show a threshold in NuSTAR spectral S/N is essential for such measurements. High energy spectral breaks are detected in the majority of the sample, and for the rest strong constraints to E cut or T e are obtained. Strikingly, we find extraordinarily large E cut lower limits (> 400 keV, up to > 800 keV) in 10 radio-quiet sources, whereas none in the radio-loud sample. Consequently and surprisingly, we find significantly larger mean E cut /T e of radio-quiet sources compared with radio-loud ones. The reliability of these measurements are carefully inspected and verified with simulations. We find a strong positive correlation between E cut and photon index Γ, which can not be attributed to the parameter degeneracy. The strong dependence of E cut on Γ, which could fully account for the discrepancy of E cut distribution between radio-loud and radio-quiet sources, indicates the X-ray coronae in AGNs with steeper hard X-ray spectra have on average higher temperature and thus smaller opacity. However, no prominent correlation is found between E cut and λ edd . In the l-Θ diagram, we find a considerable fraction of sources lie beyond the boundaries of forbidden regions due to runaway pair production, posing (stronger) challenges to various (flat) coronal geometries.

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Section: The Underlying Mechanismssupporting

confidence: 79%

Section: The Underlying Mechanismssupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The X-ray coronae in NuSTAR bright active galactic nuclei

Kang,

Wang

2022

Preprint

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“…One of the constraints to get good estimate of E 𝑐𝑢𝑡 on a large sample of AGN is the lack of high signal to noise ratio data at energies beyond 50 keV, where the cut-off in the spectrum is defined. Though more measurements are now available from instruments such as NuSTAR (Fabian et al 2015;Buisson et al 2018;Kamraj et al 2018;Tortosa et al 2018;Ricci et al 2018;Rani & Stalin 2018;Rani et al 2019;Kang et al 2020;Baloković et al 2020;Akylas & Georgantopoulos 2021;Hinkle & Mushotzky 2021;Kamraj et al 2022), it is important to increase such measurements on a larger number of sources, firstly to find good estimates of E 𝑐𝑢𝑡 and secondly to find better constraints on the correlation of E 𝑐𝑢𝑡 with other physical properties of the sources. Also, variation in the temperature of the corona is now known in few radio-quiet category of AGN (Zhang et al 2018;Barua et al 2020Barua et al , 2021aKang et al 2021;Wilkins et al 2022;Pal et al 2022), however, it is not clear if it is shown by all AGN.…”

Section: Introductionmentioning

confidence: 99%

X-ray spectral and timing analysis of the Compton Thick Seyfert 2 galaxy NGC 1068

Pal

Stalin

Parker

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We present the timing and spectral analysis of the Compton Thick Seyfert 2 active galactic nuclei NGC 1068 observed using NuSTAR and XMM-Newton. In this work for the first time we calculated the coronal temperature ($\rm {kT_{e}}$) of the source and checked for its variation between the epochs if any. The data analysed in this work comprised of (a) eight epochs of observations with NuSTAR carried out during the period December 2012 to November 2017, and, (b) six epochs of observations with XMM-Newton carried out during July 2000 to February 2015. From timing analysis of the NuSTAR observations, we found the source not to show any variations in the soft band. However, on examination of the flux at energies beyond 20 keV, during August 2014 and August 2017 the source was brighter by about 20 per cent and 30 per cent respectively compared to the mean flux of the three 2012 NuSTAR observations as in agreement with earlier results in literature. From an analysis of XMM-Newton data we found no variation in the hard band (2 − 4 keV) between epochs as well as within epochs. In the soft band (0.2 − 2 keV), while the source was found to be not variable within epochs, it was found to be brighter in epoch B relative to epoch A. By fitting physical models we determined $\rm {kT_{e}}$ to range between 8.46$^{+0.39}_{-0.66}$ keV and 9.13$^{+0.63}_{-0.98}$ keV. From our analysis, we conclude that we found no variation of $\rm {kT_{e}}$ in the source.

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Tracking the spectral properties across the different epochs in ESO 511-G030

Middei,

Petrucci,

Bianchi

et al. 2023

Preprint

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The Type I active galactic nucleus (AGN) ESO 511-G030, a formerly bright and soft-excess dominated source, has been observed in 2019 in the context of a multi-wavelength monitoring campaign. However, in these novel exposures, the source was found in a ∼10 times lower flux state, without any trace of the soft-excess. Interestingly, the X-ray weakening corresponds to a comparable fading of the UV suggesting a strong link between these components. The UV/X-ray spectral energy distribution (SED) of ESO 511-G030 shows remarkable variability. We tested both phenomenological and physically motivated models on the data finding that the overall emission spectrum of ESO 511-G030 in this extremely low flux state is the superposition of a power-law-like continuum (Γ ∼1.7) and two reflection components emerging from hot and cold matter. has Both the primary continuum and relativistic reflection are produced in the inner regions. The prominent variability of ESO 511-G030 and the lack of a soft-excess can be explained by the dramatic change in the observed accretion rate, which dropped from an L/L Edd of 2% in 2007 to 0.2% in 2019. The X-ray photon index also became harder during the low flux 2019 observations, perhaps as a result of a photon starved X-ray corona.

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X-ray Coronal Properties of Swift/BAT-Selected Seyfert 1 Active Galactic Nuclei

Cited by 3 publications

References 62 publications

The X-ray coronae in NuSTAR bright active galactic nuclei

The X-ray coronae in NuSTAR bright active galactic nuclei

X-ray spectral and timing analysis of the Compton Thick Seyfert 2 galaxy NGC 1068

Tracking the spectral properties across the different epochs in ESO 511-G030

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