AGN with extreme X-ray amplitude variations

Grupe, D.; Komossa, Stefanie; Leighly, Karen M.; Gallo, L. C.

doi:10.1051/epjconf/20123906001

Cited by 8 publications

(11 citation statements)

References 31 publications

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“…Long gaps of several months occur each year when Mrk 335 is unobservable with Swift because of its proximity to the Sun. Mrk 335 came out of the Swift Sun constraint on 16 May 2020 (Grupe et al 2020) and we resumed our monitoring (Figs. 1 and 2).…”

Section: Swift Xrtmentioning

confidence: 99%

Lifting the curtain: The Seyfert galaxy Mrk 335 emerges from deep low-state in a sequence of rapid flare events

Komossa

Grupe

Gallo

et al. 2020

A&A

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Context. The narrow-line Seyfert 1 galaxy Mrk 335 was one of the X-ray brightest active galactic nuclei, but it has systematically faded since 2007. Aims. We report the discovery with Swift of a sequence of bright and rapid X-ray flare events that reveal the emergence of Mrk 335 from its ultra-deep multiyear low state. Methods. Results are based on our dedicated multiyear monitoring of Mrk 335 with Swift. Results. Unlike other bright active galactic nuclei, the optical–UV is generally not correlated with the X-rays in Mrk 335 on a timescale of days to months. This fact either implies the absence of a direct link between the two emission components; or else implies that the observed X-rays are significantly affected by (dust-free) absorption along our line of sight. The UV and optical, however, are closely correlated at the 99.99% confidence level. The UV is leading the optical by Δt = 1.5 ± 1.5 d. The Swift X-ray spectrum shows strong deviations from a single power law in all brightness states of the outbursts, indicating that significant absorption or reprocessing is taking place. Mrk 335 displays a softer-when-brighter variability pattern at intermediate X-ray count rates, which has been seen in our Swift data since 2007 (based on a total of 590 observations). This pattern breaks down at the highest and lowest count rates. Conclusions. We interpret the 2020 brightening of Mrk 335 as a decrease in column density and covering factor of a partial-covering absorber along our line of sight in the form of a clumpy accretion-disk wind that reveals an increasing portion of the intrinsic emission of Mrk 335 from the disk and/or corona region, while the optical emission-line regions receive a less variable spectral energy distribution. This then also explains why Mrk 335 was never seen to change its optical Seyfert type (not “changing look”) despite its factor ∼50 X-ray variability with Swift.

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Section: Swift Xrtmentioning

confidence: 99%

Lifting the curtain: The Seyfert galaxy Mrk 335 emerges from deep low-state in a sequence of rapid flare events

Komossa

Grupe

Gallo

et al. 2020

A&A

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“…Grupe et al (2001) showed that 4 out of 113 bright RASS objects that were also observed in ROSAT pointings showed dramatic variations. Grupe et al (2012) added another four objects to this list by means of subsequent XMM-Newton and Chandra observations. All but two are narrow-line Seyfert 1 galaxies.…”

Section: A2 Agn With Strong Intrinsic Variationsmentioning

confidence: 99%

Multiple tidal disruption flares in the active galaxy IC 3599

Campana

Mainetti

Colpi

et al. 2015

A&A

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Tidal disruption events occur when a star passes too close to a massive black hole and is totally ripped apart by tidal forces. It may also occur that the star is not close enough to the black hole to be totally disrupted, and a less dramatic event might follow. If the stellar orbit is bound and highly eccentric, just like some stars in the centre of our own Galaxy, repeated flares are expected to occur. When the star approaches the black hole tidal radius at periastron, matter might be stripped, resulting in lower intensity outbursts recurring once every orbital period. We report on Swift observations of a recent bright flare from galaxy IC 3599, which hosts an intermediate-mass black hole, where a possible tidal disruption event was observed in the early 1990s. By light curve modelling and spectral fitting, we can consistently account for events such as the non-disruptive tidal stripping of a star into a highly eccentric orbit. The recurrence time is 9.5 yr. IC 3599 is also known to host a low-luminosity active galactic nucleus. Tidal stripping from this star over several orbital passages might be able to contribute to this activity as well.

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“…OJ 287 underwent another similar high optical to X-ray flux in 2020, with the X-ray flux (0.3-10 keV) reaching the second highest reported for this source (Komossa et al 2020(Komossa et al , 2021a. Spectral studies confirm this to be the reemergence of the soft X-ray spectral state (Komossa et al 2017;Grupe et al 2017;Komossa et al 2020, and references therein) with broadband SED similar to the blazars HBL component Prince et al 2021b). The spectral similarity of the broadband emission to the blazars HBL component (Kushwaha et al 2018b as well as the temporal and polarization (Komossa et al 2020, and references therein) behavior points to a jet origin.…”

Section: Introductionmentioning

confidence: 77%

“…It has been very active since mid-November 2015, in the optical wavebands (e.g. Valtonen et al 2016;Gupta et al 2017Gupta et al , 2019 to X-ray energies (Komossa et al 2017;Grupe et al 2017;Kushwaha et al 2018a,b;Kapanadze et al 2018;Komossa et al 2020). These activities have been concurrent with the predicted (and observed) secondary BH impactinduced flares of 2015 and 2019 in the optical and infrared wavelengths (Valtonen et al 2010(Valtonen et al , 2016Dey et al 2018;Laine et al 2020), indicating a connection between the two (Komossa et al 2020;.…”

Section: Introductionmentioning

confidence: 99%

Spectral States of OJ 287 blazar from Multi-wavelength Observations with $AstroSat$

Singh,

Kushwaha,

Sinha

et al. 2021

Preprint

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We present AstroSat soft X-ray, near-UV (NUV) and far-UV (FUV) observations of a blazar, OJ 287, carried out in 2017, 2018, and 2020. The simultaneous observations with NuSTAR in 2017 provide a broad-band look encompassing NUV, FUV, soft and hard X-rays. Captured in three different broadband spectral states in three observations, the X-ray spectrum is found to be the hardest during 2018, while the high-energy-end of the simultaneous optical-FUV spectrum shows a steepening that is modeled with a broken power-law spectrum. The spectral energy distribution (SED) in 2017 shows a relatively flatter optical-FUV and soft X-ray spectra, implying an additional emission component. The 2020 optical-FUV spectrum is harder than in 2017 and 2018, with an extremely soft X-ray spectrum and a hardening above ∼1 GeV, similar to the SEDs of High-energy-peaked BL Lac objects (HBL), thereby establishing that this additional emission component has HBL-like properties. The AstroSat multi-wavelength observations trace the spectral evolution from the end-phase of the HBL component in 2017 to its disappearance in 2018 followed by its revival in 2020. A single zone leptonic model reproduces the 2018 broadband spectrum while the 2017 and 2020 SEDs require an additional HBL-like emitting zone. The spectral evolution of the high-energy-end of optical-UV spectrum, revealed by the FUV observations in 2017 and 2018, strongly suggests that X-ray spectral changes in the normal broadband spectral state of OJ 287 are primarily due to the evolution of the optical-UV synchrotron spectrum.

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AGN with extreme X-ray amplitude variations

Cited by 8 publications

References 31 publications

Lifting the curtain: The Seyfert galaxy Mrk 335 emerges from deep low-state in a sequence of rapid flare events

Lifting the curtain: The Seyfert galaxy Mrk 335 emerges from deep low-state in a sequence of rapid flare events

Multiple tidal disruption flares in the active galaxy IC 3599

Spectral States of OJ 287 blazar from Multi-wavelength Observations with $AstroSat$

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