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The overconcentrated dark halo in the strong lens SDSS J0946+1006 is a subhalo: evidence for self interacting dark matter?

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arxiv 2411.08565 v1 pith:3VD2JPW4 submitted 2024-11-13 astro-ph.CO astro-ph.GA

classification astro-ph.COastro-ph.GA
keywords darkmattersubhalohaloredshifthaloesevidenceexpected
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abstract

The nature of dark matter is poorly constrained on subgalactic scales. Alternative models to cold dark matter, such as warm dark matter or self-interacting dark matter, could produce very different dark haloes on these scales. One of the few known dark haloes smaller than a galaxy was discovered in the triple source plane strong lens system J0946+1006. Previous studies have found that this structure is much more concentrated than expected in $\Lambda$CDM, but have assumed the dark halo is at the same redshift as the main deflector ($z_{\rm main}=0.222$). In this paper, we fit for the redshift of this dark halo. We reconstruct the first two sources in the system using a forward modelling approach, allowing for additional complexity from multipole perturbations. We find that the perturber redshift is $z_{\rm halo} = {0.207}^{+0.019}_{-0.019}$, and lower bounds on the evidence strongly prefer a subhalo over a line-of-sight structure. Whilst modelling both background sources does not improve constraints on the redshift of the subhalo, it breaks important degeneracies affecting the reconstruction of multipole perturbations. We find that the subhalo is a more than $5\sigma$ outlier from the $\Lambda$CDM $v_{\rm max}$-$r_{\rm max}$ relation and has a steep profile with an average slope of $\gamma_{\rm 2D} = {-1.81}^{+0.15}_{-0.11}$ for radii between $0.75-1.25$ kpc. This steep slope might indicate dark matter self-interactions causing the subhalo to undergo gravothermal collapse; such collapsed haloes are expected to have $\gamma_{\rm 2D} \approx -2$.

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Cited by 8 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

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    astro-ph.CO 2025-01 conditional novelty 7.0 of 10

    A new suite of cosmological simulations combines the IllustrisTNG galaxy formation model with warm and self-interacting dark matter, showing that galaxies look similar across models while halo structure and power spec...

  2. A Novel Implementation of Self-Interacting Dark Matter in AREPO

    astro-ph.CO 2026-07 accept novelty 6.5 of 10

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  3. Fuzzy dark matter soliton core hosting a supermassive black hole as a dense low-mass perturber in strong gravitational lensing

    astro-ph.CO 2026-01 conditional novelty 6.0 of 10

    A soliton core of fuzzy dark matter, compressed by an embedded supermassive black hole, reproduces the observed mass profile of the ~10^6 Msun perturber in JVAS B1938+666 for FDM mass ~3.6e-21 eV and subhalo mass ~7e6 Msun.

  4. JWST lensed quasar dark matter survey IV: Stringent warm dark matter constraints from the joint reconstruction of extended lensed arcs and quasar flux ratios

    astro-ph.CO 2025-11 conditional novelty 6.0 of 10

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  5. Strong-lensing Perturber Signatures in Self-interacting Dark Matter Simulations

    astro-ph.CO 2025-10 conditional novelty 6.0 of 10

    Core-collapsed self-interacting dark matter halos in the Concerto simulations reach high enough central densities to match the perturbing masses inferred in J0946, B1938, SDP.81, and SPT2147-50.

  6. Pion dark matter in a $\theta$ vacuum: a thermal relic with sharp velocity-dependent self-interactions

    hep-ph 2025-08 conditional novelty 6.0 of 10

    A QCD-like dark sector with a theta vacuum and a dark photon portal can simultaneously reproduce the dark matter relic abundance and produce the sharply velocity-dependent self-interactions inferred from small-scale s...

  7. Disentangling the dark and stellar mass through precise lens modelling of the JWST observation of lensed quasar WFI2033--4723

    astro-ph.GA 2026-07 conditional novelty 5.0 of 10

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