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SUMMARY:Spinning Extreme-Mass-Ratio-Inspirals into an Astrophysical Black 
 Hole: Onset of Chaos at Astrophysically Realistic Spin
DTSTART;VALUE=DATE-TIME:20260705T043000Z
DTEND;VALUE=DATE-TIME:20260705T044500Z
DTSTAMP;VALUE=DATE-TIME:20261027T060803Z
UID:indico-contribution-807@indico.narit.or.th
DESCRIPTION:Speakers: Surajit Das (University of Science and Technology of
  China\, Hefei\, Anhui 230026\, China)\nThe forthcoming space-based gravit
 ational wave detectors such as LISA\, Tianqin and Taiji will unlock the lo
 w-frequency gravitational-wave sky\, offering an unprecedented probe into 
 the fundamental dynamics of gravity. A prime target for such detectors is 
 Extreme Mass Ratio Inspirals (EMRIs)—the adiabatic inspiral of a stellar
 -mass compact object into a supermassive black hole. While conventionally 
 modeled as integrable geodesic motion with radiative dissipation\, this ca
 nonical picture is fundamentally altered when the spin of the secondary co
 mpact object is considered. The inclusion of spin-curvature coupling break
 s the integrability of the system\, opening a portal to prolonged resonanc
 es and deterministic chaos. We expose a critical astrophysical ingredient\
 , dark matter halo\, that dramatically catalyzes this chaotic transition. 
 We systematically investigate the orbital dynamics of a spinning test part
 icle around a non-spinning supermassive black hole immersed in a Hernquist
  dark matter profile. Our analysis reveals that the dark matter halo profo
 undly reshapes the effective potential\, acting as a trigger for chaos. Fo
 r the first time\, we demonstrate through high-resolution Poincaré maps t
 hat chaotic features in the orbital phase space emerge at spin parameter v
 alues significantly lower—and thus far more astrophysically plausible—
 than the upper bound previously established in the literature.\nRemarkably
 \, we find that these chaotic signatures are not confined to the near-hori
 zon regime but can manifest at large distances from the central black hole
 \, with their characteristic scale spanning orders of magnitude—from fin
 e-grained structures to gross orbital deviations. This broad spatial distr
 ibution and amplified sensitivity to spin fundamentally reframe the detect
 ability of chaos in EMRIs. Our findings suggest that the gravitational-wav
 e fingerprints of nonintegrability\, imprinted on signals destined for LIS
 A and others\, are not just a mathematical curiosity but a realistic and o
 bservable feature of astrophysical systems. This opens a transformative ne
 w window for characterizing both the spacetime geometry and the ubiquitous
  dark matter environments in galactic nuclei.\n\nhttps://indico.narit.or.t
 h/event/236/contributions/807/
LOCATION:National Astronomical Research Institute of Thailand (NARIT) Andr
 omeda Meeting Room
URL:https://indico.narit.or.th/event/236/contributions/807/
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