Systematic light-curve modelling of TDEs: statistical differences between the spectroscopic classes. Issue 4 (6th August 2022)

• Record Type: Journal Article
• Authors: Nicholl, Matt; Lanning, Daniel; Ramsden, Paige; Mockler, Brenna; Lawrence, Andy; Short, Phil; Ridley, Evan J
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 515:Issue 4(2022)
• Page Start: 5604
• Page End: 5616
• Publication Date: 2022-08-06
• Subjects: black hole physics -- galaxies: nuclei -- transients: tidal disruption events; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stac2206
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: With the sample of observed tidal disruption events (TDEs) now reaching several tens, distinct spectroscopic classes have emerged: TDEs with only hydrogen lines (TDE-H), only helium lines (TDE-He), or hydrogen in combination with He ii and often N iii /O iii (TDE-H + He). Here, we model the light curves of 32 optically bright TDEs using the Modular Open Source Fitter for Transients (mosfit ) to estimate physical and orbital properties, and look for statistical differences between the spectroscopic classes. For all types, we find a shallow distribution of star masses, compared to a typical initial mass function, in the range ∼0.1–1 M⊙, and no TDEs with very deep encounters. Our main result is that TDE-H events appear to come from less complete disruptions (and possibly lower SMBH masses) than TDE-H+He, with TDE-He events fully disrupted. We also find that TDE-H events have more extended photospheres, in agreement with recent literature, and argue that this could be a consequence of differences in the self-intersection radii of the debris streams. Finally, we identify an approximately linear correlation between black hole mass and radiative efficiency. We suggest that TDE-H may be powered by collision-induced outflows at relatively large radii, while TDE-H + He could result from prompt accretion discs, formed more efficiently in closer encounters around more massive SMBHs.