Live to die another day: the rebrightening of AT2018fyk as a repeating partial tidal disruption event

Wevers, T.; Coughlin, E. R.; Pasham, D. R.; Guolo, M.; Sun, Y.; Wen, S.; Jonker, P. G.; Zabludoff, A.; Malyali, A.; Arcodia, R.; Liu, Z.; Merloni, A.; Rau, A.; Grotova, I.; Short, P.; Cao, Z.

doi:10.48550/arxiv.2209.07538

Cited by 4 publications

(6 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…20 strongly suggests repeating TDEs in GSN 069 whose peaks (we ignore here the precursors) are separated by 3340 d ( 9.1 yr). Similar recurrent optical or X-ray flares that can be interpreted as repeating TDEs have been recently reported in ASASSN-14ko (Payne et al 2021), eRASSt J045650.3-203750 (Liu et al 2022b, and AT2018fyk (Wevers et al 2022a), with source-dependent timescales ranging from 100−200 d to 3 yr. One striking property of both TDEs in GSN 069 is that their X-ray emission evolves on much longer timescales than typical TDEs. The X-ray flux decays by a factor of ∼ 6.8 in ∼ 9 yr, and the corresponding bolometric luminosity drops by an even smaller factor of ∼ 3 (see Fig.…”

Section: The Tde-qpe Connectionsupporting

confidence: 76%

Repeating tidal disruptions in GSN 069: Long-term evolution and constraints on quasi-periodic eruptions’ models

Miniutti¹,

Giustini²,

Arcodia³

et al. 2023

A&A

View full text Add to dashboard Cite

Context. GSN 069 is the first galactic nucleus where quasi-periodic eruptions (QPEs) have been identified in December 2018. These are high-amplitude, soft X-ray bursts recurring every ∼ 9 hr, lasting ∼ 1 hr, and during which the X-ray count rate increases by up to two orders of magnitude with respect to an otherwise stable quiescent level. The X-ray spectral properties and the long-term evolution of GSN 069 in the first few years since its first X-ray detection in 2010 are consistent with a long-lived tidal disruption event (TDE). Aims. We aim to derive the properties of QPEs and of the long-term X-ray evolution in GSN 069 over the past 12 yr. Methods. We analyse timing and spectral X-ray data from 11 XMM-Newton, one Chandra, and 34 Swift observations of GSN 069 on timescales ranging from minutes to years. Results. QPEs in GSN 069 are a transient phenomenon with a lifetime of 1.05 yr. The QPE intensity and recurrence time oscillate and allow for alternating strong-weak QPEs and long-short recurrence times to be defined. In observations with QPEs, the quiescent level exhibits a quasi-periodic oscillation with a period equal to the average separation between consecutive QPEs. The QPE spectral evolution is consistent with thermal emission from a very compact region that heats up quickly and subsequently cools down via X-ray emission while expanding by a factor of ∼ 3 in radius. The long-term evolution of the quiescent level is characterised by two repeating TDEs ∼ 9 yr apart. We detect a precursor X-ray flare prior to the second TDE that may be associated with the circularisation phase during disc formation. A similar precursor flare is tentatively detected just before the first TDE. Conclusions. We provide a comprehensive summary of observational results that can be used to inform further theoretical and numerical studies on the origin of QPEs in GSN 069 and we discuss our results in terms of currently proposed QPE models. Future X-ray observations of GSN 069 promise that the QPE origin and the relation between QPEs and repeating TDEs in this galactic nucleus will be constrained, with consequences for the other sources where QPEs have been identified.

show abstract

Section: The Tde-qpe Connectionsupporting

confidence: 76%

Repeating tidal disruptions in GSN 069: Long-term evolution and constraints on quasi-periodic eruptions’ models

Miniutti¹,

Giustini²,

Arcodia³

et al. 2023

A&A

View full text Add to dashboard Cite

show abstract

“…which is obviously too long to explain the observed periods 1 year (Payne et al 2021;Wevers et al 2022). Even if one could inject the theoretical maximum energy into the star, and thus set c = 1 in Equation (4), we would obtain PNT ≃ 10 3 yr. As argued by Cufari et al (2022), even in this overly optimistic scenario, PNTs need an additional mechanism to bind the star sufficiently tightly to the SMBH to produce their observed periods in situ.…”

Section: Discussionmentioning

confidence: 94%

“…Some current models for PNTs and QPEs suggest that they can be produced by stars on bound orbits about SMBHs with periods from hours to ∼ years, with the star being partially disrupted and feeding an accretion flare every pericenter passage (Miniutti et al 2019;King 2020;Payne et al 2021;King 2022;Wevers et al 2022). PNTs have been suggested to have system parameters that are comparable to • = 10 7 ⊙ , ★ = 1 ⊙ , ★ = 1 ⊙ , which gives, from Equation ( 4) with c = 0.025,…”

Section: Discussionmentioning

confidence: 99%

Tidal capture of stars by supermassive black holes: implications for periodic nuclear transients and quasi-periodic eruptions

Cufari,

Nixon,

Coughlin

2023

Preprint

View full text Add to dashboard Cite

Stars that plunge into the center of a galaxy are tidally perturbed by a supermassive black hole (SMBH), with closer encounters resulting in larger perturbations. Exciting these tides comes at the expense of the star's orbital energy, which leads to the naive conclusion that a smaller pericenter (i.e., a closer encounter between the star and SMBH) always yields a more tightly bound star to the SMBH. However, once the pericenter distance is small enough that the star is partially disrupted, morphological asymmetries in the mass lost by the star can yield an increase in the orbital energy of the surviving core, resulting in its ejection -not capture -by the SMBH. Using smoothed-particle hydrodynamics simulations, we show that the combination of these two effects -tidal excitation and asymmetric mass loss -result in a maximum amount of energy lost through tides of ∼ 2.5% of the binding energy of the star, which is significantly smaller than the theoretical maximum of the total stellar binding energy. This result implies that stars that are repeatedly partially disrupted by SMBHs many ( 10) times on short-period orbits ( few years), as has been invoked to explain the periodic nuclear transient ASASSN-14ko and quasi-periodic eruptions, must be bound to the SMBH through a mechanism other than tidal capture, such as a dynamical exchange (i.e., Hills capture).

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Tidal capture of stars by supermassive black holes: implications for periodic nuclear transients and quasi-periodic eruptions

Cufari

Nixon

Coughlin

2022

Monthly Notices of the Royal Astronomical Society: Letters

View full text Add to dashboard Cite

Stars that plunge into the center of a galaxy are tidally perturbed by a supermassive black hole (SMBH), with closer encounters resulting in larger perturbations. Exciting these tides comes at the expense of the star’s orbital energy, which leads to the naive conclusion that a smaller pericenter (i.e. a closer encounter between the star and SMBH) always yields a more tightly bound star to the SMBH. However, once the pericenter distance is small enough that the star is partially disrupted, morphological asymmetries in the mass lost by the star can yield an increase in the orbital energy of the surviving core, resulting in its ejection – not capture – by the SMBH. Using smoothed-particle hydrodynamics simulations, we show that the combination of these two effects – tidal excitation and asymmetric mass loss – result in a maximum amount of energy lost through tides of $\sim 2.5{{\%}}$ of the binding energy of the star, which is significantly smaller than the theoretical maximum of the total stellar binding energy. This result implies that stars that are repeatedly partially disrupted by SMBHs many (≳ 10) times on short-period orbits (≲ few years), as has been invoked to explain the periodic nuclear transient ASASSN-14ko and quasi-periodic eruptions, must be bound to the SMBH through a mechanism other than tidal capture, such as a dynamical exchange (i.e. Hills capture).

show abstract

Live to die another day: the rebrightening of AT2018fyk as a repeating partial tidal disruption event

Cited by 4 publications

References 52 publications

Repeating tidal disruptions in GSN 069: Long-term evolution and constraints on quasi-periodic eruptions’ models

Repeating tidal disruptions in GSN 069: Long-term evolution and constraints on quasi-periodic eruptions’ models

Tidal capture of stars by supermassive black holes: implications for periodic nuclear transients and quasi-periodic eruptions

Tidal capture of stars by supermassive black holes: implications for periodic nuclear transients and quasi-periodic eruptions

Contact Info

Product

Resources

About