A Radio, Optical, UV, and X-Ray View of the Enigmatic Changing-look Active Galactic Nucleus 1ES 1927+654 from Its Pre- to Postflare States

Laha, Sibasish; Meyer, Eileen T.; Roychowdhury, Agniva; González, J. Becerra; Acosta–Pulido, J. A.; Thapa, Aditya Singh; Ghosh, Ritesh; Behar, E.; Gallo, Luigi; Kriss, G. A.; Panessa, F.; Bianchi, S.; Franca, F. La; Scepi, Nicolas; Begelman, Mitchell C.; Longinotti, A. L.; Lusso, Elisabeta; Oates, S. R.; Nicholl, M.; Cenko, S. Bradley

doi:10.3847/1538-4357/ac63aa

Cited by 20 publications

(40 citation statements)

References 77 publications

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“…Others have suggested that possibly a magnetic flux inversion occurred in the accretion disk of 1ES 1927+654, whereby an advection event allowed magnetic flux with opposite polarity to propagate inward in the disk (Scepi et al 2021). The arguments supporting this idea include a delayed X-ray dip relative to the UV peak, a corresponding dip in the radio, and the return to the pre-outburst state following this event (Scepi et al 2021;Laha et al 2022). This model is thus in line with the interpretation put forth in this work if the anomalous flux inversion event creates a geometrically thick inner accretion flow.…”

Section: Clagn and Tdesmentioning

confidence: 99%

Evolution of a Relativistic Outflow and X-Ray Corona in the Extreme Changing-look AGN 1ES 1927+654

Masterson

Kara

Ricci

et al. 2022

ApJ

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1ES 1927+654 is a paradigm-defying active galactic nucleus (AGN) and one of the most peculiar X-ray nuclear transients. In early 2018, this well-known AGN underwent a changing-look event, in which broad optical emission lines appeared and the optical flux increased. Yet, by 2018 July, the X-ray flux had dropped by over two orders of magnitude, indicating a dramatic change in the inner accretion flow. With three years of observations with NICER, XMM-Newton, and NuSTAR, we present the X-ray evolution of 1ES 1927+654, which can be broken down into three phases: (1) an early super-Eddington phase with rapid variability in X-ray luminosity and spectral parameters, (2) a stable super-Eddington phase at the peak X-ray luminosity, and (3) a steady decline back to the pre-outburst luminosity and spectral parameters. For the first time, we witnessed the formation of the X-ray corona, as the X-ray spectrum transitioned from thermally dominated to primarily Comptonized. We also track the evolution of the prominent, broad 1 keV feature in the early X-ray spectra and show that this feature can be modeled with blueshifted reflection (z = −0.33) from a single-temperature blackbody irradiating spectrum using xillverTDE, a new flavor of the xillver models. Thus, we propose that the 1 keV feature could arise from reflected emission off the base of an optically thick outflow from a geometrically thick, super-Eddington inner accretion flow, connecting the inner accretion flow with outflows launched during extreme accretion events (e.g., tidal disruption events). Lastly, we compare 1ES 1927+654 to other nuclear transients and discuss applications of xillverTDE to super-Eddington accretors.

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Section: Clagn and Tdesmentioning

confidence: 99%

Evolution of a Relativistic Outflow and X-Ray Corona in the Extreme Changing-look AGN 1ES 1927+654

Masterson

Kara

Ricci

et al. 2022

ApJ

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“…To date, a few dozen Seyfert galaxies and quasars have been known to have changed their optical spectral type, for example NGC 3516 (Collin-Souffrin et al 1973, Mehdipour et al 2022, NGC 7603 (Tohline & Osterbrock 1976;Kollatschny et al 2000), NGC 4151 (Penston & Perez 1984), Fairall 9 (Kollatschny & Fricke 1985, NGC 7582 (Aretxaga et al 1999), NGC 2617 (Shappee et al 2014), Mrk 590 (Denney et al 2014), HE 1136-2304(Parker et al 2016Zetzl et al 2018;Kollatschny et al 2018), Mrk 1018(McElroy et al 2016Husemann et al 2016;Kim et al 2018;Lyu et al 2021), 1ES 1927+654 (Trakhtenbrot et al 2019, Ricci et al 2020, Laha et al 2022, NGC 1566 (Oknyansky et al 2019;Parker et al 2019), and references therein. Further recent findings are based on spectral variations detected in large-scale surveys, such as the Sloan Digital Sky Survey (SDSS; e.g., Komossa et al 2008;LaMassa et al 2015;Rumbaugh et al 2018;MacLeod et al 2019), the Catalina Realtime Transient Survey (Graham et al 2020), or the Wide-field Infrared Survey Explorer (Stern et al 2018).…”

Section: Introductionmentioning

confidence: 99%

The outburst of the changing-look AGN IRAS 23226-3843 in 2019

Kollatschny

Grupe

Parker

et al. 2023

A&A

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Aims. IRAS 23226-3843 has previously been classified as a changing-look active galactic nucleus (AGN) based on observations taken in the 1990s in comparison to X-ray data (Swift, XMM-Newton, and NuSTAR) and optical spectra taken after a very strong X-ray decline in 2017. In 2019, Swift observations revealed a strong rebrightening in X-ray and UV fluxes. We aimed to study this outburst in greater detail. Methods. We took follow-up Swift, XMM-Newton, and NuSTAR observations of IRAS 23226-3843 together with optical spectra (SALT and SAAO 1.9 m telescope) from 2019 until 2021. Results. IRAS 23226-3843 showed a strong X-ray and optical outburst in 2019. It varied in the X-ray continuum by a factor of 5 and in the optical continuum by a factor of 1.6 within two months. This corresponds to a factor of 3 after correction for the host galaxy contribution. The Balmer and Fe ii emission-line intensities showed comparable variability amplitudes during the outburst in 2019. The Hα emission-line profiles of IRAS 23226-3843 changed from a blue-peaked profile in the years 1997 and 1999 to a broad double-peaked profile in 2017 and 2019. However, there were no major profile variations in the extremely broad double-peaked profiles despite the strong intensity variations in 2019. One year after the outburst, IRAS 23226-3843 changed its optical spectral type and became a Seyfert type 2 object in 2020. Blue outflow components are present in the optical Balmer lines and in the Fe band in the X-rays. A deep broadband XMM-Newton/NuSTAR spectrum was taken during IRAS 23226-3843's maximum state in 2019. This spectrum is qualitatively very similar to a spectrum taken in 2017, but by a factor of 10 higher. The soft X-ray band appears featureless. The soft excess is well modeled with a Comptonization model. A broadband fit with a power-law continuum, Comptonized soft excess, and Galactic absorption gives a good fit to the combined EPIC-pn and NuSTAR spectrum. In addition, we see a complex and broadened Fe K emission-line profile in the X-rays. The changing-look character in IRAS 23226-3843 is most probably caused by changes in the accretion rate -based on the short-term variations on timescales of weeks to months.

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“…These results clearly show that the disk/corona interaction in Mrk 590 does not follow the typical disk-corona properties of Seyfert 1 AGNs and has unique characteristics. In this context we note that there has been a recent discovery of a changing look phenomenon in an AGN 1ES 1927+654 (Trakhtenbrot et al 2019;Ricci et al 2020b;Laha et al 2022) the origin of which is still debated. However, the radio, optical, UV and Xray observations point towards an increase of accretion probably due to magnetic flux inversion, as the primary cause of this event (Scepi et al 2021;Laha et al 2022).…”

Section: Changing Look Nature Due To Change In Disk Profiles?mentioning

confidence: 86%

The origin of the vanishing soft X-ray excess in the changing-look Active Galactic Nucleus Mrk 590

Ghosh,

Laha,

Deshmukh

et al. 2022

Preprint

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We have studied the nature and origin of the soft X-ray excess detected in the interesting changinglook AGN (CLAGN) Mrk 590 using two decades of multi-wavelength observations from XMM-Newton, Suzaku, Swift and NuSTAR. In the light of vanishing soft excess in this CLAGN, we test two models, "the warm Comptonization" and "the ionized disk reflection" using extensive UV/X-ray spectral analysis. Our main findings are: (1) the soft X-ray excess emission, last observed in 2004, vanished in 2011, and never reappeared in any of the later observations, (2) we detected a significant variability (∼ 300%) in the observed optical-UV and power-law flux between observations with the lowest state (L bol = 4.4 × 10 43 erg s −1 , in 2016) and the highest state (L bol = 1.2 × 10 44 erg s −1 , in 2018), (3) the UV and power-law fluxes follow same temporal pattern, (4) the photon index showed a significant variation (Γ = 1.88 +0.02 −0.08 and Γ = 1.58 +0.02 −0.03 in 2002 and 2021 respectively) between observations, (5) no Compton hump was detected in the source spectra but a narrow FeK α line is present in all observations, (6) we detected a high-energy cut-off in power-law continuum (92 +55 −25 keV and 60 +10 −08 keV) with the latest NuSTAR observations, (7) the warm Comptonization model needs an additional diskbb component to describe the source UV bump, (8) there is no correlation between the Eddington rate and the soft excess as found in other changing-look AGNs. We conclude that given the spectral variability in UV/X-rays, the ionized disk reflection or the warm Comptonization models may not be adequate to describe the vanishing soft excess feature observed in Mrk 590.

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A Radio, Optical, UV, and X-Ray View of the Enigmatic Changing-look Active Galactic Nucleus 1ES 1927+654 from Its Pre- to Postflare States

Cited by 20 publications

References 77 publications

Evolution of a Relativistic Outflow and X-Ray Corona in the Extreme Changing-look AGN 1ES 1927+654

Evolution of a Relativistic Outflow and X-Ray Corona in the Extreme Changing-look AGN 1ES 1927+654

The outburst of the changing-look AGN IRAS 23226-3843 in 2019

The origin of the vanishing soft X-ray excess in the changing-look Active Galactic Nucleus Mrk 590

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