HLX-1 as a Repeating Partial Tidal Disruption Event around an Intermediate-Mass Black Hole
Abstract
ESO 243−49 HLX--1 is one of the first known compelling intermediate-mass black hole (IMBH) candidates, but the origin of its recurrent X-ray outbursts remains unsettled. In this work we fit the HLX--1 outbursts simultaneously with a relativistic thin-disk time-dependent model. The black-hole and disk-geometry parameters are tied across epochs, while the injected mass and timing parameters are fitted separately for each outburst. We also include a contemporaneous \textit{HST} UV/optical/IR spectral energy distribution obtained near the peak of one outburst, which constrains the global temperature and radius scales of the disk. The soft-state data are consistent with a common global solution, with black hole mass log10(M•/M⊙)=4.5±0.2 and disk formation radius log10(r0/rg)=3.8±0.3. The differences between outbursts are mainly described by modest changes in disk mass and viscous timescales. The inferred injected masses are typically ∼ 10−3 M⊙ per outburst, requiring a total fuel supply of at least a few × 10−3 M⊙ across the observed sequence. This mass scale, and the disk size, are consistent with repeated partial stripping of a low-mass donor. A simple Keplerian mapping of the flare gaps and fitted disk radius implies a highly eccentric orbit with a pericenter just outside the donor's tidal radius. These results support a repeating partial tidal disruption interpretation for the origin of HLX--1.
Related
- Observations of Repeating Tidal Disruption Events
- High-energy neutrinos from shocked circumnuclear material around optically-bright and infrared-only tidal disruption events
- Wandering intermediate-mass black holes and off-nuclear tidal disruption events from early star clusters
- Electromagnetic alignment and jet precession around supermassive black holes: Quasi-periodic oscillations in tidal disruption events
- Multi-messenger View of White Dwarf Tidal Disruption Events by Intermediate-Mass Black Holes: I. Gravitational Waves and Disk Photon and Neutrino Emissions
BibTeX
@misc{yu2026hlx1,
title = {{HLX-1 as a Repeating Partial Tidal Disruption Event around an Intermediate-Mass Black Hole}},
author = {Fangyuan Yu and Andrew Mummery and Muryel Guolo},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.38694},
eprint = {2609.38694},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.38694},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - HLX-1 as a Repeating Partial Tidal Disruption Event around an Intermediate-Mass Black Hole
AU - Fangyuan Yu
AU - Andrew Mummery
AU - Muryel Guolo
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.38694
UR - https://arxiv.org/abs/2609.38694
AB - ESO 243−49 HLX--1 is one of the first known compelling intermediate-mass black hole (IMBH) candidates, but the origin of its recurrent X-ray outbursts remains unsettled. In this work we fit the HLX--1 outbursts simultaneously with a relativistic thin-disk time-dependent model. The black-hole and disk-geometry parameters are tied across epochs, while the injected mass and timing parameters are fitted separately for each outburst. We also include a contemporaneous \textit{HST} UV/optical/IR spectral energy distribution obtained near the peak of one outburst, which constrains the global temperature and radius scales of the disk. The soft-state data are consistent with a common global solution, with black hole mass log_10(M_•/M_⊙)=4.5±0.2 and disk formation radius log_10(r_0/r_g)=3.8±0.3. The differences between outbursts are mainly described by modest changes in disk mass and viscous timescales. The inferred injected masses are typically ∼ 10^−3 M_⊙ per outburst, requiring a total fuel supply of at least a few × 10^−3 M_⊙ across the observed sequence. This mass scale, and the disk size, are consistent with repeated partial stripping of a low-mass donor. A simple Keplerian mapping of the flare gaps and fitted disk radius implies a highly eccentric orbit with a pericenter just outside the donor's tidal radius. These results support a repeating partial tidal disruption interpretation for the origin of HLX--1.
ER -