2024/01/30 by Debojyoti Garain, Garain, Debojyoti, Tapobrata Sarkar +1 · 2 citations
Physics and Astronomy · #Cosmology and Gravitation Theories #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Astrophysical Phenomena (astro-ph.HE) #Pulsars and Gravitational Waves Research #Relativity and Gravitational Theory
paper · pdf · doi:10.48550/arxiv.2401.17031
openalex publication_date 2024/01/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Intermediate-mass black holes (IMBHs, ∼ 102-105M\odot) are often dubbed as the missing link between stellar mass (\lesssim 102M\odot) and super-massive (\gtrsim 105-6 M\odot) BHs. Observational signatures of these can result from tidal disruptions of white dwarfs (WDs), which would otherwise be captured as a whole by super-massive BHs. Recent observations indicate that IMBHs might be rapidly spinning, while it is also known that isolated white dwarfs might have large spins, with spin periods of the order of minutes. Here, we aim to understand the effects of ``coupling'' between BH and stellar spin, focussing on the tidal disruption of spinning WDs in the background of spinning IMBHs. Using smoothed particle hydrodynamics, we perform a suite of numerical simulations of partial tidal disruptions, where spinning WDs are in eccentric orbits about spinning IMBHs. We take a hybrid approach, where we integrate the Kerr geodesic equations while being in a regime where we can treat the internal stellar fluid dynamics in the Newtonian limit. The coupling of BH and stellar spin results in distinctive behaviour of mass distribution of debris, compared to non-rotating cases. Further, while late time fallback rates of debris into the BH is unaffected by only BH spin, these have noticeable deviations in the presence of stellar spin, in particular, this causes a broadening of the fallback curves at late times. On the other hand, gravitational wave signatures are unaffected by stellar spin in the parameter regime that we consider.