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The large cores of dark matter and globular clusters in AS1063. Possible evidence of self-interacting dark matter. Or not

Jose M. Diego

TL;DR

This paper exploits deep JWST imaging of AS1063 to compare the spatial distributions of dark matter and globular clusters, testing predictions from CDM, SIDM, and ψDM. By fitting core profiles and analyzing their sizes, it finds a DM core of roughly 150 kpc and a GC core of about 70 kpc, with the DM core being substantially larger. The results argue that standard CDM struggles to produce such large cores in clusters, while SIDM with a velocity-dependent cross section around the order of 0.3 cm^2 g^-1 can naturally reproduce the observed DM core and the relatively smaller GC core, potentially aided by core stalling and ongoing mergers. However, the authors emphasize that the lack of ultra-high-resolution simulations resolving ~10^5 GCs in cluster halos prevents a definitive exclusion of CDM, and they call for future simulations to clarify the interplay between GC populations and DM core formation. The study thus highlights a path toward constraining the nature of dark matter through high-fidelity cluster-scale simulations combined with JWST-driven observations.

Abstract

Deep JWST images of AS1063 reveals tens of thousands of globular clusters in the galaxy cluster AS1063. When compared with the lensing model based on the same JWST data, the distribution of globular clusters traces closely the distribution of lensing mass (mostly composed of dark matter). Interestingly, both the distributions of dark matter and globular clusters have large central cores. However the size of the core in the distribution of globular clusters is about half the size the core of the dark matter distribution. We argue that the standard cold dark matter and fuzzy dark matter models struggle to explain these large cores. Meanwhile, the self interacting dark matter with a velocity dependent cross section, combined with core stalling, offers a natural explanation to the existence of these cores if $σ_{\rm SI}\approx 0.3$ cm$^2$ g$^{-1}$ for galaxy cluster halos. But we also discuss how the lack of hydrodynamical N-body simulations capable of resolving globular clusters in galaxy cluster scale halos, hinders the possibility of ruling out the standard non-collisional dark matter scenario. Future high-resolution hydrodynamical simulations of galaxy clusters, with several trillion particles, and containing over a hundred thousand globular clusters, can provide the insight needed to transform the epistemic nature of dark matter into an ontological one

The large cores of dark matter and globular clusters in AS1063. Possible evidence of self-interacting dark matter. Or not

TL;DR

This paper exploits deep JWST imaging of AS1063 to compare the spatial distributions of dark matter and globular clusters, testing predictions from CDM, SIDM, and ψDM. By fitting core profiles and analyzing their sizes, it finds a DM core of roughly 150 kpc and a GC core of about 70 kpc, with the DM core being substantially larger. The results argue that standard CDM struggles to produce such large cores in clusters, while SIDM with a velocity-dependent cross section around the order of 0.3 cm^2 g^-1 can naturally reproduce the observed DM core and the relatively smaller GC core, potentially aided by core stalling and ongoing mergers. However, the authors emphasize that the lack of ultra-high-resolution simulations resolving ~10^5 GCs in cluster halos prevents a definitive exclusion of CDM, and they call for future simulations to clarify the interplay between GC populations and DM core formation. The study thus highlights a path toward constraining the nature of dark matter through high-fidelity cluster-scale simulations combined with JWST-driven observations.

Abstract

Deep JWST images of AS1063 reveals tens of thousands of globular clusters in the galaxy cluster AS1063. When compared with the lensing model based on the same JWST data, the distribution of globular clusters traces closely the distribution of lensing mass (mostly composed of dark matter). Interestingly, both the distributions of dark matter and globular clusters have large central cores. However the size of the core in the distribution of globular clusters is about half the size the core of the dark matter distribution. We argue that the standard cold dark matter and fuzzy dark matter models struggle to explain these large cores. Meanwhile, the self interacting dark matter with a velocity dependent cross section, combined with core stalling, offers a natural explanation to the existence of these cores if cm g for galaxy cluster halos. But we also discuss how the lack of hydrodynamical N-body simulations capable of resolving globular clusters in galaxy cluster scale halos, hinders the possibility of ruling out the standard non-collisional dark matter scenario. Future high-resolution hydrodynamical simulations of galaxy clusters, with several trillion particles, and containing over a hundred thousand globular clusters, can provide the insight needed to transform the epistemic nature of dark matter into an ontological one
Paper Structure (7 sections, 2 equations, 2 figures)

This paper contains 7 sections, 2 equations, 2 figures.

Table of Contents

  1. Introduction
  2. The cores of the GC system and the DM distribution in AS1063
  3. Dynamical state of AS1063
  4. The case for CDM
  5. The case for SIDM
  6. The case for $\psi$DM
  7. Conclusions

Figures (2)

  • Figure 1: Comparison of the lensing mass and GC profiles with analytical models. The dark blue (lensing mass) and black (GCs) lines are from paper-I and paper-II respectively. For the GC, the profile is corrected for background contamination. The solid black curve is re-scaled by a factor 4 to visually match the lensing profile. The green curve is an NFW profile that matches the lensing profile in the region constrained by lensing (blue vertical dotted lines). The green line is a PIEMD profile fitting the lensing mass from alternative lens models (see text). The red line is a Burkert profile fitting the lensing mass profile while the orange line is a different Burkert profile fitting the distribution of GCs. The dashed-black is the number density of the brightest GCs in the full sample obtained after increasing the detection threshold by one order of magnitude (and containing 4061 GCs, or one seventh the total number in the full catalog). The dashed black line includes the same factor 4 as the black solid line. Finally, the dashed orange line is the same Burkert profile shown as a solid-orange line with $r_b=70$ kpc but divided by a factor seven.
  • Figure 2: Central $3"\times3"$ region of AS1063 (filtered). The image is obtained after two high-pass filters are applied to the F090W, F115W, F150W and F200W images Diego2026c, and combining the four filtered images into a single one. Many GCs can be seen in the image with an almost uniform number density. The yellow and cyan solid lines are the light contours in the raw F356W image at $50\%$ and $25\%$, respectively, of the maximum intensity in the center. The yellow and cyan dashed curves are ellipses fitting the corresponding solid lines. The small yellow and cyan circles near the bright central source are the corresponding centers of the two ellipses. The bright source near the center is at the position of the peak emission in the raw images and it is likely the central SMBH.