Tidal disruption events from supermassive black hole binaries

Coughlin, Eric R.; Armitage, Philip J.; Nixon, Chris; Begelman, Mitchell C.

doi:10.1093/mnras/stw2913

Cited by 84 publications

(92 citation statements)

References 87 publications

(118 reference statements)

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“…We note that the disruptive effect of a SMBH binary on the debris stream of the TDE 30 might also help to explain the fact that the flare observed in F01004-2237 is unusually prolonged.…”

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confidence: 87%

A tidal disruption event in the nearby ultra-luminous infrared galaxy F01004-2237

et al. 2017

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Tidal disruption events (TDEs), in which stars are gravitationally disrupted as they pass close to the supermassive black holes in the centres of galaxies 1 , are potentially important probes of strong gravity and accretion physics. Most TDEs have been discovered in large-area monitoring surveys of many 1000s of galaxies, and the rate deduced for such events is relatively low: one event every 10 4 -10 5 years per galaxy 2-4 . However, given the selection effects inherent in such surveys, considerable uncertainties remain about the conditions that favour TDEs. Here we report the detection of unusually strong and broad helium emission lines following a luminous optical flare (M v <-20.1 mag) in the nucleus of the nearby ultra-luminous infrared galaxy F01004-2237. The particular combination of variability and post-flare emission line spectrum observed in F01004-2237 is unlike any known supernova or active galactic nucleus. Therefore, the most plausible explanation for this phenomenon is a TDE-the first detected in a galaxy with an ongoing massive starburst. The fact that this event has been detected in repeat spectroscopic observations of a sample of 15 ultra-luminous infrared galaxies over a period of just 10 years suggests that the rate of TDEs is much higher in such objects than in the general galaxy population.Ultra-luminous infrared galaxies (ULIRGs: L IR > 10 12 L ¤ ) 5 represent the peaks of major, gas-rich galaxy mergers in which the merger-induced gas flows concentrate the gas into the nuclear regions, leading to high rates of star formation and accretion onto the central supermassive black holes. The nearby ULIRG F01004-2237 (RA: 01h 02m 50.007s and Dec: -22d 21m 57.22s (J2000); z=0.117835) was observed using deep spectroscopic observations in September 2015 as part of a study of 15 ULIRGs to examine the importance of the warm gas outflows driven by active galactic nuclei (AGNs) in such objects 6 . Many of its properties are typical of local ULIRGs, including relatively modest total stellar and supermassive black hole masses, and evidence for AGN activity in the form of blue-shifted high ionization emission lines 6 . However, it is unusual in the sense that it is one of the few ULIRGs in which Wolf-Rayet features have been detected at optical wavelengths 9 , indicating the presence of a population of ~3×10 4 Wolf-Rayet stars with ages 3-6 Myr (supplementary information). Also, unlike most ULIRGs for which the central starburst regions are heavily enshrouded in dust, this source has a compact nucleus that is barely resolved in optical and UV observations with the Hubble Space Telescope (HST) and has been attributed to a population of stars that is both young ( < 10 Myr) and massive (~3×10 8 M ¤ ) 10 . Together, these features suggest that we have an unusually clear view of the nuclear star forming regions in F01004-2237. However, the 2015 spectra are markedly different: the ~4660Å feature is a factor of 5.6+/-1.1 stronger in flux compared with 2000, and the blend has developed broad wings that extend up to...

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“…We note that the disruptive effect of a SMBH binary on the debris stream of the TDE 30 might also help to explain the fact that the flare observed in F01004-2237 is unusually prolonged.…”

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confidence: 87%

A tidal disruption event in the nearby ultra-luminous infrared galaxy F01004-2237

et al. 2017

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“…In this paper, we discuss a new electromagnetic window into the assembly of BBH mergers in dense stellar clusters (SCs): tidal disruptions (TDs) of stars by BBHs. Previous theoretical work on these events suggests that their lightcurves are interrupted on characteristic timescales related to the orbital period of the disrupting BBHs [e.g., 64,[72][73][74][75]. We propose that populations of such events can be used to probe the orbital period distribution of BBHs inside SCs.…”

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confidence: 95%

Probing the black hole merger history in clusters using stellar tidal disruptions

et al. 2019

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The dynamical assembly of binary black holes (BBHs) in dense star clusters (SCs) is one of the most promising pathways for producing observable gravitational wave (GW) sources, however several other formation scenarios likely operate as well. One of the current outstanding questions is how these different pathways may be distinguished apart. In this paper we suggest a new multimessenger observable that can be used to constrain the formation of BBH mergers originating from SCs: the electromagnetic signal from tidal disruptions (TDs) of stars by BBHs. Such TDs will show variability in their light curve from the orbital motion of the disruptive BBHs, and can therefore be used to map the BBH orbital period distribution, and thereby also the dynamical mechanisms that eventually drive the BBHs to merger. Using an analytical approach including General Relativistic effects, we find that the orbital period distribution of BBHs within globular clusters peaks on timescales of days, which we argue is unique to this assembly pathway. We propose that the search for variable TDs in current and future EM transient surveys might be used to constrain the merger history of BBHs in SCs.

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“…Since then, a number of other authors have analyzed the tidal disruption of polytropes, with the aim of assessing one or another aspect of the tidal disruption process (e.g. Hayasaki et al 2013;Coughlin & Nixon 2015;Shiokawa et al 2015;Bonnerot et al 2016;Hayasaki et al 2016;Coughlin et al 2016;Mainetti et al 2017;Guillochon & McCourt 2017;Bonnerot et al 2017;Coughlin et al 2017;Wu et al 2018;Golightly et al 2019). However, only relatively few authors have analyzed the disruption of a star with a density profile other than a polytrope.…”

Section: Introductionmentioning

confidence: 99%

On the Diversity of Fallback Rates from Tidal Disruption Events with Accurate Stellar Structure

Golightly

Nixon

Coughlin

2019

ApJL

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The tidal disruption of stars by supermassive black holes (SMBHs) can be used to probe the SMBH mass function, the properties of individual stars, and stellar dynamics in galactic nuclei. Upcoming missions will detect thousands of TDEs, and accurate theoretical modeling is required to interpret the data with precision. Here we analyze the influence of more realistic stellar structure on the outcome of TDEs; in particular, we compare the fallback rates -being the rate at which tidally-disrupted debris returns to the black hole -from progenitors generated with the stellar evolution code mesa to γ ≃ 4/3 and γ = 5/3 polytropes. We find that mesa-generated density profiles yield qualitatively-different fallback rates as compared to polytropic approximations, and that only the fallback curves from lowmass (1M ⊙ or less), zero-age main-sequence stars are well fit by either a γ ≃ 4/3 or 5/3 polytrope. Stellar age has a strong affect on the shape of the fallback curve, and can produce characteristic timescales (e.g., the time to the peak of the fallback rate) that greatly differ from the polytropic values. We use these differences to assess the degree to which the inferred black hole mass from the observed lightcurve can deviate from the true value, and find that the discrepancy can be at the order of magnitude level. Accurate stellar structure also leads to a substantial variation in the critical impact parameter at which the star is fully disrupted, and can increase the susceptibility of the debris stream to fragmentation under its own self-gravity. These results suggest that detailed modeling is required to accurately interpret observed lightcurves of TDEs.

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Tidal disruption events from supermassive black hole binaries

Cited by 84 publications

References 87 publications

A tidal disruption event in the nearby ultra-luminous infrared galaxy F01004-2237

A tidal disruption event in the nearby ultra-luminous infrared galaxy F01004-2237

Probing the black hole merger history in clusters using stellar tidal disruptions

On the Diversity of Fallback Rates from Tidal Disruption Events with Accurate Stellar Structure

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