Self-interacting dark matter delays bar growth in an isolated gas-rich galactic disk: torque-resolved numerical evidence
Abstract
We investigate how a dynamically responsive gas disk changes the influence of self-interacting dark matter (SIDM) on stellar-bar formation. In an isolated Milky-Way-mass galaxy with fixed total baryonic mass, the gas-rich collisionless (CDM) model develops a persistent bar at 1.96 Gyr, whereas the matched SIDM model with sigmam=1 cm2 g−1 does so at 2.69 Gyr. The final stellar m=2 amplitude is 0.437 in CDM and 0.340 in SIDM, a 22 per cent suppression; the corresponding gas-free controls remain weak over the same interval. An independently sampled gas-rich pair preserves the direction of both differences. Direct component-force measurements show that the SIDM stellar disk loses 2.82×1011 Msun kpc kms less angular momentum than its CDM counterpart. The integrated torque contrast is dominated by the dark halo (approximately 74 per cent), with a substantial gas contribution (26 per cent), and is redistributed in radius and time rather than being a uniform reduction of halo coupling. Conservation, force-accuracy, aperture, threshold, and independent-sampling checks support the ordering as a dynamical effect within this model. The result demonstrates that a live gas component can change both the sign and timing of the early SIDM impact inferred from collisionless disks, providing a mechanism-based constraint for future hydrodynamic SIDM studies.
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BibTeX
@misc{kang2026selfinteracting,
title = {{Self-interacting dark matter delays bar growth in an isolated gas-rich galactic disk: torque-resolved numerical evidence}},
author = {Dong-Biao kang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.18343},
eprint = {2609.18343},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.18343},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Self-interacting dark matter delays bar growth in an isolated gas-rich galactic disk: torque-resolved numerical evidence
AU - Dong-Biao kang
PY - 2026
DA - 2026/09/16
PB - arXiv
DO - 10.48550/arxiv.2609.18343
UR - https://arxiv.org/abs/2609.18343
AB - We investigate how a dynamically responsive gas disk changes the influence of self-interacting dark matter (SIDM) on stellar-bar formation. In an isolated Milky-Way-mass galaxy with fixed total baryonic mass, the gas-rich collisionless (CDM) model develops a persistent bar at 1.96 Gyr, whereas the matched SIDM model with sigmam=1 cm^2 g^−1 does so at 2.69 Gyr. The final stellar m=2 amplitude is 0.437 in CDM and 0.340 in SIDM, a 22 per cent suppression; the corresponding gas-free controls remain weak over the same interval. An independently sampled gas-rich pair preserves the direction of both differences. Direct component-force measurements show that the SIDM stellar disk loses 2.82×10^11 Msun kpc kms less angular momentum than its CDM counterpart. The integrated torque contrast is dominated by the dark halo (approximately 74 per cent), with a substantial gas contribution (26 per cent), and is redistributed in radius and time rather than being a uniform reduction of halo coupling. Conservation, force-accuracy, aperture, threshold, and independent-sampling checks support the ordering as a dynamical effect within this model. The result demonstrates that a live gas component can change both the sign and timing of the early SIDM impact inferred from collisionless disks, providing a mechanism-based constraint for future hydrodynamic SIDM studies.
ER -