A maximum X-ray luminosity scale of disc-dominated tidal disruption events

Abstract

We develop a model describing the dynamical and observed properties of disc-dominated TDEs around black holes with the lowest masses ($M\lesssim \mathrm{few}\times 10^6{M}_{\odot }$). TDEs around black holes with the lowest masses are most likely to reach super-Eddington luminosities at early times in their evolution. By assuming that the amount of stellar debris which can form into a compact accretion disc is set dynamically by the Eddington luminosity, we make a number of interesting and testable predictions about the observed properties of bright soft-state X-ray TDEs and optically bright, X-ray dim TDEs. We argue that TDEs around black holes of the lowest masses will expel the vast majority of their gravitationally bound debris into a radiatively driven outflow. A large-mass outflow will obscure the innermost X-ray producing regions, leading to a population of low black hole mass TDEs which are only observed at optical \& UV energies. TDE discs evolving with bolometric luminosities comparable to their Eddington luminosity will have near constant (i.e. black hole mass independent) X-ray luminosities, of order $L_{\mathrm{X},\max }\equiv L_M\sim 10^{43}-10^{44}$ erg/s. The range of luminosity values stems primarily from the range of allowed black hole spins. A similar X-ray luminosity limit exists for X-ray TDEs in the hard (Compton scattering dominated) state, and we therefore predict that the X-ray luminosity of the brightest X-ray TDEs will be at the scale $L_M(a)\sim 10^{43}-10^{44}$ erg/s, independent of black hole mass and accretion state. These predictions are in strong agreement with the properties of the existing population ($\sim 40$ sources) of observed TDEs.

v2: Minor changes to match published journal version, some references added and Figure 11 modified. v1: 11 pages, 15 figures, 1 table. Accepted for publication in MNRAS

References in corpus (11)

• UV/Optical Detections of Candidate Tidal Disruption Events by GALEX and CFHTLS
• Evolution of tidal disruption candidates discovered by XMM-Newton
• X-ray Brightening and UV Fading of Tidal Disruption Event ASASSN-15oi
• Black hole masses of tidal disruption event host galaxies II
• A likely decade-long sustained tidal disruption event
• The spectral evolution of disc dominated tidal disruption events
• Fainter harder brighter softer: a correlation between ${\alpha }_{\mathrm{ox}}$ , X-ray spectral state and Eddington ratio in tidal disruption events
• Long-term radio and X-ray evolution of the tidal disruption event ASASSN-14li
• An X-ray and UV flare from the galaxy XMMSL1 J061927.1-655311
• The general relativistic thin disc evolution equation
• ASASSN-15lh: a TDE about a maximally rotating $10^9{M}_{\odot }$ black hole

Cited by in corpus (9)

• Candidate Tidal Disruption Event AT2019fdr Coincident with a High-Energy Neutrino
• Magnetically Dominated Disks in Tidal Disruption Events and Quasi-Periodic Eruptions
• Interpretation of the observed neutrino emission from three Tidal Disruption Events
• A Case for a Binary Black Hole System Revealed via Quasi-Periodic Outflows
• The population of tidal disruption events discovered with eROSITA
• Micro Tidal Disruption Events in Active Galactic Nuclei
• The Rapidly Spinning Intermediate-Mass Black Hole 3XMM J150052.0+015452
• The X-ray variability of tidal disruption events
• On the origin of late-time X-ray flares in UV/optically-selected tidal disruption events