Tidal Disruption Signatures as Probes of Sgr A*'s Spin Evolution

Building on Ciurlo et al.'s fascinating observations of X7's extreme tidal evolution, this research direction proposes treating such events as "cosmic spinometers." While current work (like Wang & Zhang 2024) infers past mergers from Sgr A*'s current spin state, we'd use the detailed morphological changes in tidally disrupted objects to back-calculate the spin at the time of disruption. By developing hydrodynamic simulations that incorporate different spin magnitudes and orientations, we could create a predictive framework linking observed deformation patterns, brightness evolution, and velocity gradients to specific spin parameters. This would allow us to not only confirm Wang & Zhang's merger hypothesis but also potentially map out Sgr A*'s spin evolution over time by studying multiple disrupted objects at different evolutionary stages. The novelty lies in transforming these "swansongs" from curiosities into quantitative probes of fundamental black hole properties.

References:

1. The Swansong of the Galactic Center Source X7: An Extreme Example of Tidal Evolution near the Supermassive Black Hole. A. Ciurlo, R. Campbell, M. Morris, T. Do, A. Ghez, E. Becklin, R. Bentley, D. Chu, A. Gautam, Y. Gursahani, A. Hees, K. K. O’neil, Jessica R. Lu, G. Martinez, S. Naoz, S. Sakai, Rainer Schoedel (2023). Astrophysical Journal.
2. Evidence of a past merger of the Galactic Centre black hole. Yihan Wang, Bing Zhang (2024). Nature Astronomy.