KIPAC Tea Talk: XRISM view of Accretion-Driven Winds Variability and Feedback in NGC 4151 and future JWST prospects / From Pulsar Magnetospheres to Neutron-Star Inference:First-Principles Hotspot Physics and New Computational Frameworks

Xiang Abstract: Active galactic nuclei (AGN) accretion-disk winds in X-ray observations evolve on short timescales and are closely coupled to accretion-state changes, providing a direct observational link between inner disk variability and multiphase outflows. NGC 4151 is a nearby (z = 0.0033) Seyfert 1 - 1.8 changing look AGN (CL-AGN) known to have one of the richest wind structures yet found in a single source to date, including stratified, multiphase outflows ranging from slow "warm absorbers" (WAs; vout ~ 100-1000 km s-1), "very fast outflows" (VFOs; vout 103-104 km s-1), to "ultrafast outflows" (UFOs; vout ~ 0.033-0.33 c). The Resolve calorimeter spectrometer aboard XRISM provides the highest X-ray spectral resolution currently available in Fe K band, while NGC 4151 provides the brightest and highest-quality AGN wind spectrum. This combination therefore provides a major step forward in resolving how AGN winds are structured, launched, how they vary, and how they respond to the changes in the central engine. We present a detailed, time-variable spectral analysis of Fe K band in XRISM/Resolve observations of NGC 4151 spanning a total exposure of 893 ks. I will also place this XRISM study in the context of a broader research program by extending wind analyses across AGN with different accretion rates and connecting nuclear X-ray winds to multiphase feedback.

Huang Abstract: Neutron-star observations are now precise enough that the next major advances will depend not only on better data， but also on more physical forward models and more powerful inference tools. In this talk， I will present a research program aimed at connecting pulsar magnetospheric physics， X-ray pulse-profile modeling， and dense-matter inference within a unified framework. I will first highlight new results that derive， from first principles and in analytic form， the surface return-current distribution in multipolar pulsar magnetospheres， providing a physically consistent route from global magnetic geometry to polar-cap heating and X-ray pulse profile. I will then briefly introduce two computational frameworks that make this broader program practical: a new public GPU-accelerated X-ray pulse-profile modeling framework， which reduces high-fidelity waveform evaluations from minutes to milliseconds， and CompactObject， an open-source full-scope platform for neutron-star equation-of-state inference that combines X-ray， gravitational-wave， radio， and nuclear constraints. Together， these developments provide a pathway from first-principles pulsar physics to robust neutron star dense matter constraints， with ongoing applications including physics-motivated hotspot inference for PSR J0740+6620 using NICER data and future NewAthena mission