Revisiting self-interacting dark matter with DESI DR2 baryon acoustic oscillation observations
Abstract
We revisit self-interacting dark matter (SIDM), originally proposed to resolve small-scale CDM problems and drive late-time cosmic acceleration. Using latest DESI BAO, Pantheon+/DESY5 type Ia supernova, and cosmic chronometer Hubble data, we constrain three representative SIDM scenarios including creation and annihilation. We focus on the annihilation of dark matter particles in model SIDM1; our findings indicate the effective annihilation cross section is log10(κC1)=−4.32 (with an upper limit of log10(κC1)=−3.90). For the SIDM2 model, the SIDM fluid behaves similarly to a dark energy component with a mildly dynamical equation of state (wSIDM=−0.82 ± 0.04). We also quantitatively discuss the dark matter self-interactions in a more general SIDM model (SIDM3), which reveals a strong correlation between the annihilation cross section and equation of state of dark matter. For the three SIDM models, the measured Hubble constant agrees with that derived from the recent Planck 2018 results; both are inconsistent with the results of the SH0ES collaboration, who report a significantly higher H0 value. The Bayesian evidence indicates that SIDM2 and SIDM3 are more supported by the available observational data than the concordance standard ΛCDM. Furthermore, the cosmological constraints on the effective annihilation parameter can be translated into bounds on the velocity-averaged annihilation cross section and the self-interaction cross section per unit mass. While low-redshift data alone imply a relatively large cross section, the inclusion of cosmic microwave background distance priors significantly tightens the constraint at cluster-scale velocities, highlighting the necessity of a velocity-dependent cross section to reconcile cosmological and astrophysical observations.
Versions
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BibTeX
@misc{zhu2026revisiting,
title = {{Revisiting self-interacting dark matter with DESI DR2 baryon acoustic oscillation observations}},
author = {Yixuan Zhu and Shuo Cao and Xuanni chen and Xuchen Tai and Xinyang Jin and Yuanming Feng},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.26877},
eprint = {2610.26877},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.26877},
}
RIS
TY - UNPB
TI - Revisiting self-interacting dark matter with DESI DR2 baryon acoustic oscillation observations
AU - Yixuan Zhu
AU - Shuo Cao
AU - Xuanni chen
AU - Xuchen Tai
AU - Xinyang Jin
AU - Yuanming Feng
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2610.26877
UR - https://arxiv.org/abs/2610.26877
AB - We revisit self-interacting dark matter (SIDM), originally proposed to resolve small-scale CDM problems and drive late-time cosmic acceleration. Using latest DESI BAO, Pantheon+/DESY5 type Ia supernova, and cosmic chronometer Hubble data, we constrain three representative SIDM scenarios including creation and annihilation. We focus on the annihilation of dark matter particles in model SIDM1; our findings indicate the effective annihilation cross section is log_10(κC_1)=−4.32 (with an upper limit of log_10(κC_1)=−3.90). For the SIDM2 model, the SIDM fluid behaves similarly to a dark energy component with a mildly dynamical equation of state (w_SIDM=−0.82 ± 0.04). We also quantitatively discuss the dark matter self-interactions in a more general SIDM model (SIDM3), which reveals a strong correlation between the annihilation cross section and equation of state of dark matter. For the three SIDM models, the measured Hubble constant agrees with that derived from the recent Planck 2018 results; both are inconsistent with the results of the SH0ES collaboration, who report a significantly higher H_0 value. The Bayesian evidence indicates that SIDM2 and SIDM3 are more supported by the available observational data than the concordance standard ΛCDM. Furthermore, the cosmological constraints on the effective annihilation parameter can be translated into bounds on the velocity-averaged annihilation cross section and the self-interaction cross section per unit mass. While low-redshift data alone imply a relatively large cross section, the inclusion of cosmic microwave background distance priors significantly tightens the constraint at cluster-scale velocities, highlighting the necessity of a velocity-dependent cross section to reconcile cosmological and astrophysical observations.
ER -