Tidal Disruption Event Demographics with the Zwicky Transient Facility: Volumetric Rates, Luminosity Function, and Implications for the Local Black Hole Mass Function

By Yuhan Yao, V. Ravi, S. Gezari, Sanne G M van Velzen, Wenbin Lu, S. Schulze, J. Somalwar, Shrinivas R. Kulkarni, E. Hammerstein, M. Nicholl and 19 more. Astrophysical Journal Letters, 2023

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We conduct a systematic tidal disruption event (TDE) demographics analysis using the largest sample of optically selected TDEs. A flux-limited, spectroscopically complete sample of 33 TDEs is constructed using the Zwicky Transient Facility over 3 yr (from 2018 October to 2021 September). We infer the black hole (BH) mass (M BH) with host galaxy scaling relations, showing that the sample M BH ranges from 105.1 M ⊙ to 108.2 M ⊙. We developed a survey efficiency corrected maximum volume method to infer the rates. The rest-frame g-band luminosity function can be well described by a broken power law of ϕ(Lg)∝Lg/Lbk0.3+Lg/Lbk2.6−1 , with L bk = 1043.1 erg s−1. In the BH mass regime of 105.3 ≲ (M BH/M ⊙) ≲ 107.3, the TDE mass function follows ϕ(MBH)∝MBH−0.25 , which favors a flat local BH mass function ( dnBH/dlogMBH≈constant ). We confirm the significant rate suppression at the high-mass end (M BH ≳ 107.5 M ⊙), which is consistent with theoretical predictions considering direct capture of hydrogen-burning stars by the event horizon. At a host galaxy mass of M gal ∼ 1010 M ⊙, the average optical TDE rate is ≈3.2 × 10−5 galaxy−1 yr−1. We constrain the optical TDE rate to be [3.7, 7.4, and 1.6] × 10−5 galaxy−1 yr−1 in galaxies with red, green, and blue colors.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/e8d91570a30f38dcb89054f8d15225fe64c093d4