Self-lensing of electromagnetic counterparts to extreme mass ratio inspirals
Abstract
Extreme mass ratio inspirals on inclined orbits can produce recurrent electromagnetic flares by shocking gas at accretion-disk crossings. Using forward ray tracing in Kerr spacetime, we investigate how self-lensing by the central supermassive black hole (SMBH) reshapes these flares. Flares emitted behind the SMBH can be strongly magnified, whereas near-side flares remain almost unmagnified, producing strong-weak alternation even for identical intrinsic emission. As Lense-Thirring precession shifts the crossing azimuths, it generates long-term amplitude envelopes whose spacing can be used to infer the precession period. Lense-Thirring precession can also increase the cumulative geometric lensing probability over longer observing windows. Within individual flares, Keplerian motion of hotspots co-rotating with the disk produces time-dependent magnification, which can generate shoulders or double peaks and change the effective width. We also propose a spectral diagnostic to distinguish self-lensing from external lensing when their light curves are similar: self-lensing can amplify later, cooler emission and produce a softer secondary peak, whereas delayed images from a static external lens repeat the same intrinsic spectral evolution.
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BibTeX
@misc{zhou2026selflensing,
title = {{Self-lensing of electromagnetic counterparts to extreme mass ratio inspirals}},
author = {Ruwen Zhou and Zhen Pan},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.02645},
eprint = {2611.02645},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.02645},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Self-lensing of electromagnetic counterparts to extreme mass ratio inspirals
AU - Ruwen Zhou
AU - Zhen Pan
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.02645
UR - https://arxiv.org/abs/2611.02645
AB - Extreme mass ratio inspirals on inclined orbits can produce recurrent electromagnetic flares by shocking gas at accretion-disk crossings. Using forward ray tracing in Kerr spacetime, we investigate how self-lensing by the central supermassive black hole (SMBH) reshapes these flares. Flares emitted behind the SMBH can be strongly magnified, whereas near-side flares remain almost unmagnified, producing strong-weak alternation even for identical intrinsic emission. As Lense-Thirring precession shifts the crossing azimuths, it generates long-term amplitude envelopes whose spacing can be used to infer the precession period. Lense-Thirring precession can also increase the cumulative geometric lensing probability over longer observing windows. Within individual flares, Keplerian motion of hotspots co-rotating with the disk produces time-dependent magnification, which can generate shoulders or double peaks and change the effective width. We also propose a spectral diagnostic to distinguish self-lensing from external lensing when their light curves are similar: self-lensing can amplify later, cooler emission and produce a softer secondary peak, whereas delayed images from a static external lens repeat the same intrinsic spectral evolution.
ER -