Constraints on the Self-Interaction Cross-Section of Dark Matter from Numerical Simulations of the Merging Galaxy Cluster 1E 0657-5 - AstrophysicsReport as inadecuate




Constraints on the Self-Interaction Cross-Section of Dark Matter from Numerical Simulations of the Merging Galaxy Cluster 1E 0657-5 - Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: Abridged We compare recent results from X-ray, strong lensing, weaklensing, and optical observations with numerical simulations of the merginggalaxy cluster 1E0657-56. X-ray observations reveal a bullet-like subclusterwith a prominent bow shock, while lensing results show that the positions ofthe total mass peaks are consistent with the centroids of the collisionlessgalaxies and inconsistent with the X-ray brightness peaks. Previous studies,based on older observational datasets, have placed upper limits on theself-interaction cross-section of dark matter per unit mass, sigma-m, usingsimplified analytic techniques. In this work, we take advantage of new,higher-quality observational datasets by running N-body simulations of1E0657-56 that include the effects of self-interacting dark matter, andcomparing the results with observations. Furthermore, the recent data allow fora new independent method of constraining sigma-m, based on the non-observationof an offset between the bullet subcluster mass peak and galaxy centroid. Thisnew method places an upper limit 68% confidence of sigma-m < 1.25 cm^2-g. Ifwe make the assumption that the subcluster and the main cluster had equalmass-to-light ratios prior to the merger, we derive our most stringentconstraint of sigma-m < 0.7 cm^2-g, which comes from the consistency of thesubclusters observed mass-to-light ratio with the main clusters, and with theuniversal cluster value, ruling out the possibility of a large fraction of darkmatter particles being scattered away due to collisions. Our limit is a slightimprovement over the previous result from analytic estimates, and rules outmost of the 0.5 - 5cm^2-g range invoked to explain inconsistencies between thestandard collisionless cold dark matter model and observations.



Author: Scott W. Randall, Maxim Markevitch, Douglas Clowe, Anthony H. Gonzalez, Marusa Bradac

Source: https://arxiv.org/



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