Super Rad Reverberations

by David Cyncynates (ICTP Trieste)

Wednesday Oct 21, 2026, 12:00 PM → 2:00 PM Europe/Madrid

C7b/058 - Seminar (IFAE Main Building C7b)

Black hole superradiance can populate the surroundings of rapidly spinning black holes with dense clouds of ultralight bosons. If these fields interact with Standard Model particles, their presence may leave observable signatures in the emission from surrounding accretion discs. In this talk, I will explore how Fe K$\alpha$ fluorescence lines can be used to search for such clouds in black hole X-ray binary systems. Focusing on a quadratic coupling to electrons, I will show how coherent oscillations of the bosonic field modify the energy of the Fe K$\alpha$ atomic transition, producing characteristic time-dependent distortions of the observed X-ray spectrum. I will present a matched-template search strategy and forecasts for its sensitivity, accounting for the stochastic variability of the X-ray corona and the dynamical response of the accretion disc. For representative benchmark parameters, discovery sensitivity may be achievable with week-scale exposure times, placing this approach within reach of existing X-ray telescopes and archival datasets depending on the model parameters. Finally, I will discuss prospects for extending these searches to a broader range of superradiant cloud phenomenology, including axionlike particles.