Measuring Stellar and Black Hole Masses of Tidal Disruption Events

Ryu, Taeho; Krolik, Julian H.; Piran, Tsvi

doi:10.3847/1538-4357/abbf4d

Cited by 76 publications

(73 citation statements)

References 45 publications

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“…35 ; however, a TDE-specific relationship, which includes TDE demographics, indicates scattering around M ≈ 10 6 M ⊙ for that bulge mass 36 . A new method based on TDE dynamics 37 gives an estimate of M ≈ 1.3 × 10 6 M ⊙ for AT2019dsg, consistent with our choice. We stress that should a higher black-hole mass be established in the future, our model would remain valid, although with modified parameters.…”

Section: Methodssupporting

confidence: 83%

A concordance scenario for the observed neutrino from a tidal disruption event

Winter

Lunardini

2021

Nat Astron

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During a tidal disruption event, a star is torn apart by the tidal forces of a supermassive black hole, with about 50% of the star's mass eventually accreted by the black hole. The resulting flare can, in extreme cases of super-Eddington mass accretion, result in a relativistic jet [1][2][3][4] . While tidal disruption events have been theoretically proposed as sources of high-energy cosmic rays 5,6 and neutrinos 7-14 , stacking searches indicate that their contribution to the diffuse extragalactic neutrino flux is very low 15 . However, a recent association of a track-like astrophysical neutrino (IceCube-191001A 16 ) with a tidal disruption event (AT2019dsg 17 ) indicates that some tidal disruption events can accelerate cosmic rays to petaelectronvolt energies. Here we introduce a phenomenological concordance scenario with a relativistic jet to explain this association: an expanding cocoon progressively obscures the X-rays emitted by the accretion disk, while at the same time providing a sufficiently intense external target of backscattered X-rays for the production of neutrinos via proton-photon interactions. We also reproduce the delay (relative to the peak) of the neutrino emission by scaling the production radius with the black-body radius. Our energetics and assumptions for the jet and the cocoon are compatible with expectations from numerical simulations of tidal disruption events.On 1 October 2019, a track-like astrophysical neutrino (named IceCube-191001A) was detected 16 ; a dedicated multimessenger follow-up programme revealed the tidal disruption event (TDE) AT2019dsg as a candidate source, with a P value of 0.2% to 0.5% of random association 17 , corresponding to ~3σ significance. The neutrino followed the peak of the AT2019dsg light curve by t − t peak = 154 d and had a most likely energy E ≈ 0.2 PeV (ref. 16 and links therein). Its observation reveals a new class of cosmic ray sources, as it indicates that some TDEs can accelerate cosmic rays to petaelectronvolt energies.The TDE AT2019dsg is located at redshift z ≈ 0.05, or luminosity distance d L ≈ 230 Mpc. It was discovered in the optical-ultraviolet (UV) bands by the Zwicky Transient Facility (ZTF) on 9 April 2019 18 , and it reached its luminosity peak in this band on 30 April 2019 (t peak = 58603 modified Julian date). Several follow-up observations were conducted in the optical-UV 18 , radio 17,19,20 and X-ray 17,21,22 bands, the latter starting at t − t peak = 17 d. The picture that emerged from the observations shows a several-months-long flare, with black body (BB) spectra observed in both the optical-UV (temperature T BB = 38,900 K, photospheric radius R BB ≈ 5 × 10 14 cm) and X-ray (T X ≈ 0.06 keV, R X ≈ 3 × 10 11 -7 × 10 11 cm) bands, and luminosities L exponentially decaying over an (initial) timescale of 57.5 d and 10.3 d starting at L BB = 2.88 × 10 44 erg s −1 and L X ≈ 2.5 × 10 43 erg s −1 , respectively (Fig. 1, thick black and blue curves). The quoted X-ray luminosity is for an energy window [0.3-8.0] keV, whereas an X-ray

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Section: Methodssupporting

confidence: 83%

A concordance scenario for the observed neutrino from a tidal disruption event

Winter

Lunardini

2021

Nat Astron

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“…In this case the star will be completely swallowed before it is disrupted (MacLeod, Guillochon & Ramirez-Ruiz 2012 ), resulting in no observable TDE. At the opposite end of the mass scale, the lowest inferred black hole masses are 5 × 10 5 M (Wevers et al 2017 ;Mockler, Guillochon & Ramirez-Ruiz 2019 ;Ryu, Krolik & Piran 2020 ;Zhou et al 2021 ). It is worth noting that several different methods are being used to estimate black hole masses in TDEs.…”

Section: Simulation Grid Setupmentioning

confidence: 99%

“…Alternatively, a multiparameter model can be fit to the observed light curve to extract the physical properties of the TDE (Guillochon et al 2018 ;Mockler et al 2019 ). 2 In order to settle on a reasonable range of black hole masses and Eddington ratios for our simulation grid, we used the largest compilation of these parameters by (Ryu et al 2020 ). Their estimates are based on TDEMASS 3 (Ryu et al 2020 ), which assumes a slow circularization scenario for the in-falling stellar debris.…”

Section: Simulation Grid Setupmentioning

confidence: 99%

“…2 In order to settle on a reasonable range of black hole masses and Eddington ratios for our simulation grid, we used the largest compilation of these parameters by (Ryu et al 2020 ). Their estimates are based on TDEMASS 3 (Ryu et al 2020 ), which assumes a slow circularization scenario for the in-falling stellar debris. In this model, the optical emission is generated from stream-stream collisions; both black hole and stellar mass can then be estimated from the optical luminosity and colour temperature at peak flare.…”

Section: Simulation Grid Setupmentioning

confidence: 99%

“…Fig. 3 shows the black hole masses and Eddington fractions for a sample of 20 TDEs, as provided by Ryu et al ( 2020 ). We also include the TDE spectra shown in Fig.…”

Section: Simulation Grid Setupmentioning

confidence: 99%

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Optical line spectra of tidal disruption events from reprocessing in optically thick outflows

Parkinson

Knigge

Matthews

et al. 2022

Monthly Notices of the Royal Astronomical Society

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A significant number of tidal disruption events (TDEs) radiate primarily at optical and ultraviolet (UV) wavelengths, with only weak soft X-ray components. One model for this optical excess proposes that thermal X-ray emission from a compact accretion disc is reprocessed to longer wavelengths by an optically thick envelope. Here, we explore this reprocessing scenario in the context of an optically thick accretion disc wind. Using state-of-the-art Monte Carlo radiative transfer and ionization software, we produce synthetic UV and optical spectra for wind and disc-hosting TDEs. Our models are inspired by observations, spanning a realistic range of accretion rates and wind kinematics. We find that such outflows can efficiently reprocess the disc emission and produce the broad Balmer and helium recombination features commonly seen in TDEs and exhibit asymmetric red wings. Moreover, the characteristic colour temperature of the reprocessed spectral energy distribution (SED) is much lower than that of the accretion disc. We show explicitly how changes in black hole mass, accretion rate and wind properties affect the observed broadband SED and line spectrum. In general, slower, denser winds tend to reprocess more radiation and produce stronger Balmer emission. Most of the outflows we consider are too highly ionized to produce UV absorption features, but this is sensitive to the input SED. For example, truncating the inner disc at just ≃ 4 RISCO lowers the wind ionization state sufficiently to produce UV absorption features for sightlines looking into the wind.

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Extreme accretion events: TDEs and changing‐look AGN

Komossa

Grupe

2023

Astron Nachr

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We present a review of the topics of X-ray stellar tidal disruption events (TDEs) and changing-look active galactic nuclei (AGN). Stars approaching a supermassive black hole (SMBH) can be tidally disrupted and accreted. TDEs were first discovered in the X-ray regime and appear as luminous, giant-amplitude flares from inactive galaxies. The early X-ray observations with ROSAT also established the extreme X-ray spectral softness of these events with temperatures of order 50-100 eV that continues to be seen in the majority of more recently identified events. While the majority of X-ray TDEs has been identified from inactive galaxies and some showed the highest amplitudes of variability recorded from galaxy cores (amplitudes exceeding factors of 1000-6000), a small fraction of AGN has been found to be highly variable as well. In AGN, this so-called changing-look phenomenon often comes with a strong change in the optical broad emission lines, leading to Seyfert-type changes between class 1 and class 2. These two forms of activity represent the extremes of variability among active and quiescent galaxies, and have opened up a new window to understanding accretion physics under extreme conditions. Finally, we introduce the term "frozen-look AGN" to describe systems that show constant line emission despite dramatic changes in the observed ionizing continuum. These systems are best explained by strong changes of absorption along our line-of-sight.

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Measuring Stellar and Black Hole Masses of Tidal Disruption Events

Cited by 76 publications

References 45 publications

A concordance scenario for the observed neutrino from a tidal disruption event

A concordance scenario for the observed neutrino from a tidal disruption event

Optical line spectra of tidal disruption events from reprocessing in optically thick outflows

Extreme accretion events: TDEs and changing‐look AGN

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