X-ray morphology of cluster-mass haloes in self-interacting dark matter

Creators: Shen, Xuejian¹; Brinckmann, Thejs^{2, 3, 4}; Rapetti, David^{5, 6, 7}; Vogelsberger, Mark⁸; Mantz, Adam⁹; Zavala, Jesús¹⁰; Allen, Steven W.^{9, 11}

1. California Institute of Technology
2. University of Ferrara
3. INFN Sezione di Ferrara
4. Stony Brook University
5. Ames Research Center
6. Universities Space Research Association
7. University of Colorado Boulder
8. Massachusetts Institute of Technology
9. Stanford University
10. University of Iceland
11. SLAC National Accelerator Laboratory

Abstract

We perform cosmological zoom-in simulations of 19 relaxed cluster-mass haloes with the inclusion of adiabatic gas in the cold dark matter (CDM) and self-interacting dark matter (SIDM) models. These clusters are selected as dynamically relaxed clusters from a parent simulation with M₂₀₀ ≃ (1 - 3) x 10¹⁵ M⊙. Both the dark matter and the intracluster gas distributions in SIDM appear more spherical than their CDM counterparts. Mock X-ray images are generated based on the simulations and are compared to the real X-ray images of 84 relaxed clusters selected from the Chandra and ROSAT archives. We perform ellipse fitting for the isophotes of mock and real X-ray images and obtain the ellipticities at cluster-centric radii of r ≃ 0.1 - 0.2R₂₀₀. The X-ray isophotes in SIDM models with increasing cross-sections are rounder than their CDM counterparts, which manifests as a systematic shift in the distribution function of ellipticities. Unexpectedly, the X-ray morphology of the observed non-cool-core clusters agrees better with SIDM models with cross-section (σ/m) = 0.5 - 1 cm² g⁻¹ than CDM and SIDM with (σ/m) = 0.1 cm² g⁻¹. Our statistical analysis indicates that the latter two models are disfavoured at the 68 per cent confidence level (as conservative estimates). This conclusion is not altered by shifting the radial range of measurements or applying a temperature selection criterion. However, the primary uncertainty originates from the lack of baryonic physics in the adiabatic model, such as cooling, star formation and feedback effects, which still have the potential to reconcile CDM simulations with observations.

Copyright and License

This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model).

Acknowledgement

The computations in this paper were run on the Faculty of Arts and Sciences Research Computing (FASRC) Cannon cluster supported by the FAS Division of Science Research Computing Group at Harvard University. This research made use of photutils, an astropy package for detection and photometry of astronomical sources (Bradley et al. 2020). TB was supported by the US Department of Energy (DOE) grant DE-SC0017848, through the Istituto Nazionale di Fisica Nucleare of Italy (INFN) project GRANT73/Tec-Nu, and from the COSMOS network (www.cosmosnet.it) through the Italian Space Agency (ASI) Grants 2016-24-H.0 and 2016-24-H.1-2018. DR acknowledges support by the National Aeronautics and Space Administration (NASA) under award number NNA16BD14C for NASA Academic Mission Services. MV acknowledges support through NASA Astrophysics Theory Program (ATP) 19-ATP19-0019, 19-ATP19-0020, 19-ATP19-0167, and the National Science Foundation (NSF) grants AST-1814053, AST-1814259, AST-1909831, AST-2007355, and AST-2107724. JZ acknowledges support by a Grant of Excellence from the Icelandic Research fund (grant number 206930). SA acknowledges support from the US Department of Energy under contract number DE-AC02-76SF00515.

Funding

TB was supported by the US Department of Energy (DOE) grant DE-SC0017848, through the Istituto Nazionale di Fisica Nucleare of Italy (INFN) project GRANT73/Tec-Nu, and from the COSMOS network (www.cosmosnet.it) through the Italian Space Agency (ASI) Grants 2016-24-H.0 and 2016-24-H.1-2018. DR acknowledges support by the National Aeronautics and Space Administration (NASA) under award number NNA16BD14C for NASA Academic Mission Services. MV acknowledges support through NASA Astrophysics Theory Program (ATP) 19-ATP19-0019, 19-ATP19-0020, 19-ATP19-0167, and the National Science Foundation (NSF) grants AST-1814053, AST-1814259, AST-1909831, AST-2007355, and AST-2107724. JZ acknowledges support by a Grant of Excellence from the Icelandic Research fund (grant number 206930). SA acknowledges support from the US Department of Energy under contract number DE-AC02-76SF00515.

Data Availability

The simulations in this paper were run on the super-computing system Cannon at Harvard University and the data were stored on the Engaging cluster at Massachusetts Institute of Technology. The data underlying this paper can be shared on reasonable request to the corresponding author.

Software References

This research made use of photutils, an astropy package for detection and photometry of astronomical sources (Bradley et al. 2020).

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