Rates of stellar tidal disruption as probes of the supermassive black hole mass function

By Nicholas C. Stone, B. Metzger. 2014

309 citations recorded by the source corpus.

Rates of stellar tidal disruption events (TDEs) by supermassive black holes (SMBHs) due to two-body relaxation are calculated using a large galaxy sample (N=146) in order to explore the sensitivity of the TDE rates to observational uncertainties, such as the parametrization of galaxy light profiles and the stellar mass function. The largest uncertainty arises due to the poorly constrained occupation fraction of SMBHs in low-mass galaxies, which otherwise dominate the total TDE rate. The detection rate of TDE flares by optical surveys is calculated as a function of SMBH mass and other observables for several physically-motivated models of TDE emission. We also quantify the fraction of galaxies that produce deeply penetrating disruption events. If the majority of the detected events are characterized by super-Eddington luminosities (such as disk winds, or synchrotron radiation from an off-axis relativistic jet), then the measured SMBH mass distribution will tightly constrain the low-end SMBH occupation fraction. If Eddington-limited emission channels dominate, however, then the occupation fraction sensitivity is much less pronounced in a flux-limited survey (although still present in a volume-complete event sample). The SMBH mass distribution of the current sample of TDEs, though highly inhomogeneous and encumbered by selection effects, already suggests that Eddington-limited emission channels dominate. Even our most conservative rate estimates appear to be in tension with much lower observationally inferred TDE rates, and we discuss several possible resolutions to this discrepancy.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/2474d16b347aef1086a474e2ecada6fc059fd59f

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Citations in the corpus

Observational evidence for intermediate-mass black holes (2017, background): “IMBHs, with BH masses below 10 6 M , should have higher rates of stellar disruption than SMBHs (Wang & Merritt 2004; Stone & Metzger 2016); nonetheless, most TDEs (∼50; Komossa 2015) have been associated with SMBHs (e.g., Komossa & Bade 1999; Halpern et al. 2004; Lin et al. 2011, 2015; van Velzen…”
Assisted inspirals of stellar mass black holes embedded in AGN discs: solving the ‘final au problem’ (2016, result): “This is only compatible with the observed influence radii of smaller, M• ∼ 106M , SMBHs (for example, Stone & Metzger 2016 fit rinf = 16 pc(M•/10 8M ) 0.69 to a large sample of nearby galaxies).”
Nuclear star clusters (2009, background): “An important aspect of understanding the observed targets are predictions of TDE rates in galaxies, which strongly depend on the density of stars within the sphere of influence of the black hole (e.g., Stone and Metzger 2016).”
Stellar Dynamics and Stellar Phenomena Near a Massive Black Hole (2017, background): “Observations of nearby A+E galaxy NGC 3156 indeed indicate a dense nucleus that can support a high TDE rate of Γt ∼ 10−3 yr−1 (Stone & Metzger 2016).”
New Physical Insights about Tidal Disruption Events from a Comprehensive Observational Inventory at X-Ray Wavelengths (2016, background): “107.5M , the theoretical rate is ∼ 10−4 events per year (Magorrian & Tremaine 1999; Wang & Merritt 2004; Stone & Metzger 2016) .”
ASASSN-15oi: a rapidly evolving, luminous tidal disruption event at 216 Mpc (2016, result): “…implied TDE rate given the ASAS-SN discoveries was r = (2.2 − 17.0) × 10−5 yr−1 per galaxy, a range that is consistent with theoretical estimates (e.g., Stone & Metzger 2016; Kochanek 2016) while also significantly higher but consistent with the rates inferred from other optical surveys (e.g.,…”