The variability and soft X-ray excess properties of narrow-line Seyfert 1 galaxies: The<i>Swift</i>view

Ding, Nan; Gu, Qiusheng; Tang, Yonghui; Xiong, Dingrong; Guo, Xiaotong; Xu, Xinpeng; Geng, Xiongfei; Ge, Xiaomei; Chen, Y. Y.

doi:10.1051/0004-6361/202142650

Cited by 2 publications

(1 citation statement)

References 44 publications

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“…In the X-rays, we find Fvar=47% for Mrk 590 since August 2017, compared to typical values of ∼ 10-35% for moderately accreting AGN (Edelson et al 2019;Lobban et al 2020;Hernández Santisteban et al 2020;Kumari et al 2021;Vincentelli et al 2021). In fact, the X-ray variability amplitude of Mrk 590 is similar to that of Narrow Line Seyfert 1 sources, which in many cases display Fvar ∼50% (e.g., Gallo et al 2018;Cackett et al 2020;Ding et al 2022). Narrow Line Seyfert 1 sources tend to have high accretion rates, near or above the Eddington limit (e.g., Jin et al 2012).…”

Section: High Variability At a Modest Accretion Ratementioning

confidence: 45%

Flares in the changing look AGN Mrk 590 – I. The UV response to X-ray outbursts suggests a more complex reprocessing geometry than a standard disc

Lawther

Vestergaard

Raimundo

et al. 2022

Monthly Notices of the Royal Astronomical Society

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Mrk 590 is a known changing-look AGN which almost turned off in 2012, and then in 2017 partially re-ignited into a repeat flaring state, unusual for an AGN. Our Swift observations since 2013 allow us to characterise the accretion-generated emission and its reprocessing in the central engine of a changing-look AGN. The X-ray and UV variability amplitudes are higher than those typically observed in ‘steady-state’ AGN at similar moderate accretion rates; instead, the variability is similar to that of highly accreting AGN. The unusually strong X-ray to UV correlation suggests that the UV-emitting region is directly illuminated by X-ray outbursts. We find evidence that the X-rays are reprocessed by two UV components, with the dominant one at ∼3 days and a faint additional reprocessor at near-zero lag. However, we exclude a significant contribution from diffuse broad line region continuum, known to contribute for bona-fide AGN. A near-zero lag is expected for a standard ‘lamp-post’ disk reprocessing model with a driving continuum source near the black hole. That the overall UV response is dominated by the ∼3-day lagged component suggests a complicated reprocessing geometry, with most of the UV continuum not produced in a compact disk, as also found in recent studies of NGC 5548 and NGC 4151. Nonetheless, the observed flares display characteristic timescales of ∼100 rest-frame days, consistent with the expected thermal timescale in an accretion disk.

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Section: High Variability At a Modest Accretion Ratementioning

confidence: 45%

Flares in the changing look AGN Mrk 590 – I. The UV response to X-ray outbursts suggests a more complex reprocessing geometry than a standard disc

Lawther

Vestergaard

Raimundo

et al. 2022

Monthly Notices of the Royal Astronomical Society

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Probing properties of nearly two-hundred new active galactic nuclei

Ghosh,

Mandal,

Bhattacharyya

et al. 2024

Monthly Notices of the Royal Astronomical Society

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We present a comprehensive analysis of the X-ray spectral properties of 198 newly identified active galactic nuclei (AGNs), leveraging archival data from the Chandra X-ray Observatory. All these AGNs exhibit a powerlaw spectral signature spanning a broad energy range of 0.5 − 7.0 keV, characterized by the photon index (Γ) values ranging from $0.3^{+0.16}_{-0.14}$ to $2.54^{+0.14}_{-0.13}$. Particularly, 76 of these AGNs display discernible levels of intrinsic absorption, after considering the Galactic absorption. The column densities associated with this local absorption ($n_{\rm H}^{\rm local}$) are within a range of ∼1019 − 1022 cm−2. We study the cosmological evolution of AGNs using the variation of $n_{\rm H}^{\rm local}$ and Γ with their estimated redshift. The intrinsic spectral signature did not reveal any significant cosmological evolution; however, a deficit of hard sources at high redshift is possibly intrinsic. Our sample covers several orders of broadband intrinsic luminosity ($L_{\rm B}^{\rm intr}$) ranging from $4.59^{+0.41}_{-0.41} \times 10^{42}$ to $2.4^{+0.12}_{-0.12} \times 10^{46}\, {\rm erg~s}^{-1}$ with peak at 1.84 redshift. We also investigate the hardness-luminosity diagram (HLD) to further probe the AGNs. We conduct a sanity check by applying our findings to known AGNs, and the results are consistent with our observations.

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The variability and soft X-ray excess properties of narrow-line Seyfert 1 galaxies: TheSwiftview

Cited by 2 publications

References 44 publications

Flares in the changing look AGN Mrk 590 – I. The UV response to X-ray outbursts suggests a more complex reprocessing geometry than a standard disc

Flares in the changing look AGN Mrk 590 – I. The UV response to X-ray outbursts suggests a more complex reprocessing geometry than a standard disc

Probing properties of nearly two-hundred new active galactic nuclei

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