Kavli Affiliate: Erin Kara
| First 5 Authors: Joheen Chakraborty, Joheen Chakraborty, , ,
| Summary:
Quasi-Periodic Eruptions (QPEs) are luminous, recurring X-ray outbursts from
galactic nuclei, with timescales of hours to days. While their origin remains
uncertain, leading models invoke accretion disk instabilities or the
interaction of a massive black hole (MBH) with a lower-mass secondary in an
extreme mass ratio inspiral (EMRI). EMRI scenarios offer a robust framework for
interpreting QPEs by characterizing observational signatures associated with
the secondary’s orbital dynamics. This, in turn, enables extraction of the
MBH/EMRI physical properties and provides a means to test the EMRI scenario,
distinguishing models and addressing the question: what can QPE timings teach
us about massive black holes and EMRIs? In this study, we employ analytic
expressions for Kerr geodesics to efficiently resolve the trajectory of the
secondary object and perform GPU-accelerated Bayesian inference to assess the
information content of QPE timings. Using our inference framework, referred to
as QPE-FIT (Fast Inference with Timing), we explore QPE timing constraints on
astrophysical parameters, such as EMRI orbital parameters and MBH mass/spin. We
find that mild-eccentricity EMRIs ($esim0.1-0.3$) can constrain MBH mass and
EMRI semimajor axis/eccentricity to the 10% level within tens of orbital
periods, while MBH spin is unconstrained for the explored semimajor axes $geq
100R_g$ and monitoring baselines $mathcalO(10-100rm)$ orbits. Introducing a
misaligned precessing disk generally degrades inference of EMRI orbital
parameters, but can constrain disk precession properties within 10-50%. This
work both highlights the prospect of QPE observations as dynamical probes of
galactic nuclei and outlines the challenge of doing so in the multimodal
parameter space of EMRI-disk collisions.
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