SIDM and CDM interpretations of the million-solar-mass lensing perturber JVAS B1938+666-đť’±
Abstract
A 106 M⊙ object has recently been inferred from gravitational imaging of the strong-lensing system JVAS B1938+666, exhibiting an unusually dense inner region embedded within an extended envelope, far exceeding expectations for cold dark matter (CDM) halos. Using gravothermal fluid simulations, we show that such a structure arises naturally in self-interacting dark matter (SIDM) halos evolving into a deep core-collapse phase, where a secondary dense central core forms within an extended profile. The resulting density structure closely matches the inferred properties of the lensing object. We also demonstrate that a similar profile could be reproduced in CDM in the presence of an intermediate-mass black hole, but this requires an early-forming progenitor that subsequently loses $5$ orders of magnitude in mass through tidal stripping by the lens galaxy. Whether such a scenario can be realized in realistic cosmological environments remains an open question.
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BibTeX
@misc{zhang2026sidm,
title = {{SIDM and CDM interpretations of the million-solar-mass lensing perturber JVAS B1938+666-$\mathcalV$}},
author = {Xingyu Zhang and Hai-Bo Yu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.12909},
eprint = {2606.12909},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.12909},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - SIDM and CDM interpretations of the million-solar-mass lensing perturber JVAS B1938+666-đť’±
AU - Xingyu Zhang
AU - Hai-Bo Yu
PY - 2026
DA - 2026/09/24
PB - arXiv
DO - 10.48550/arxiv.2606.12909
UR - https://arxiv.org/abs/2606.12909
AB - A 10^6 M_⊙ object has recently been inferred from gravitational imaging of the strong-lensing system JVAS B1938+666, exhibiting an unusually dense inner region embedded within an extended envelope, far exceeding expectations for cold dark matter (CDM) halos. Using gravothermal fluid simulations, we show that such a structure arises naturally in self-interacting dark matter (SIDM) halos evolving into a deep core-collapse phase, where a secondary dense central core forms within an extended profile. The resulting density structure closely matches the inferred properties of the lensing object. We also demonstrate that a similar profile could be reproduced in CDM in the presence of an intermediate-mass black hole, but this requires an early-forming progenitor that subsequently loses $5$ orders of magnitude in mass through tidal stripping by the lens galaxy. Whether such a scenario can be realized in realistic cosmological environments remains an open question.
ER -