The “Little Dark Dot”: Evidence for Self-interacting Dark Matter in the Strong Lens SDSS J0946+1006?
Abstract Previous studies, based on precise modeling of a gravitationally lensing image, have identified what may be an extremely compact, dark perturber in the well-known lensing system SDSS J0946+1006 (the “Jackpot”). Its remarkable compactness challenges the standard cold dark matter paradigm. In this paper, we explore whether such a compact perturber could be explained as a core-collapse halo described by the self-interacting dark matter (SIDM) model. Using the isothermal Jeans method, we compute the density profiles of core-collapse halos across a range of masses. Our comparison with observations indicates that a core-collapse halo has an inner density profile and mass enclosed within 1 kpc that fit the data well, but only if the halo has a total mass of ∼10 11 M ⊙ . While a halo of this mass should host a detectable galaxy, the current observational upper limit on the perturber’s luminosity remains uncertain. Resolving whether or not the data support the presence of a core-collapse SIDM halo therefore requires future deep observations to measure its luminosity.
Authors
- Qiuhan He (ORCID: https://orcid.org/0000-0003-3672-9365)
- Samuel C. Lange (ORCID: https://orcid.org/0009-0007-0679-818X)
- Andrew Robertson (ORCID: https://orcid.org/0000-0002-0086-0524)
- R. Massey (ORCID: https://orcid.org/0000-0002-6085-3780)
- Carlos S. Frenk (ORCID: https://orcid.org/0000-0002-2338-716X)
- J.W Nightingale (ORCID: https://orcid.org/0000-0002-8987-7401)
- Maximilian von Wietersheim-Kramsta (ORCID: https://orcid.org/0000-0003-4986-5091)
- Fangzhou Jiang (ORCID: https://orcid.org/0000-0001-6115-0633)
- Shaun Cole (ORCID: https://orcid.org/0000-0002-5954-7903)
- Xiaoyue Cao (ORCID: https://orcid.org/0000-0003-4988-9296)
- Kaihao Wang (ORCID: https://orcid.org/0009-0005-3671-1861)
- Aristeidis Amvrosiadis (ORCID: https://orcid.org/0000-0002-4465-1564)
- Ran Li (ORCID: https://orcid.org/0000-0003-3899-0612)
- S. Z. Li (ORCID: https://orcid.org/0009-0004-0904-7400)
- Zhonghua Jia (ORCID: https://orcid.org/0009-0008-2362-1367)
- Xianghao Ma
Institutions
- Durham University (GB)
- Chinese Academy of Sciences (CN)
- Peking University (CN)
- Beijing Normal University (CN)
- Kavli Institute for Theoretical Sciences (CN)
- Carnegie Observatories (US)
- National Astronomical Observatories (CN)
- University of Chinese Academy of Sciences (CN)
- Newcastle University (GB)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2025-11-26
- DOI
- https://doi.org/10.3847/1538-4357/ae1462
- Citations
- 3
- Primary Topic
- Galaxies: Formation, Evolution, Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 3.46
Funders
- National Natural Science Foundation of China