arXiv subjects

Rashaad Reid

Publications and source records attributed to Rashaad Reid.

3 recordsLinked to original sources

arXiv2026

Tracing the dynamical states and mass accretion histories of galaxy clusters in IllustrisTNG

As the largest and most recently formed stage of hierarchical structure, present-day galaxy clusters are predicted to have a broad range of late-time assembly histories. This diversity may explain much of the scatter in scaling relations and other cluster properties. Observationally, systems with more or less recent accretion should appear as unrelaxed and relaxed clusters, respectively. However, it is unclear which of the many possible structural measures best correlate with assembly history. Using the IllustrisTNG simulations, we explore the correlation between structural parameters and assembly history. To assess the effectiveness of different structural selection criteria, we define subsamples of the most and least relaxed clusters based on the values of various intrinsic, projected, and stellar structural parameters, and then compare the median assembly history of the subsamples in each case. We find that several observable quantities, including the magnitude gap between the brightest galaxies and the asymmetry of the stellar mass distribution, are very effective in selecting cluster samples with more or less recent accretion, even when applied in projection. Given the strong correlations between assembly history and present-day cluster structure, we suggest that structural classification be included explicitly in any analysis of catalogue completeness, scaling relations, or mean density profiles.

astro-ph.CO↗

arXiv2025

Cluster properties as a function of dynamical state in the DESI Legacy x UNIONS surveys

We investigate how the dynamical state of galaxy clusters influences their galaxy populations and mass distributions. Using photometrically selected clusters from the DESI Legacy Imaging Survey cross-matched with the UNIONS galaxy shear catalogue, we classify clusters as evolved or evolving based on their rest-frame r-band magnitude gaps and stellar mass ratios between the brightest cluster galaxies (BCGs) and bright satellites. We measure the stellar mass functions, weak-lensing profiles, and radial number density and red-fraction profiles of stacked clusters in both subsamples. Evolved clusters exhibit more concentrated lensing profiles, bimodal stellar mass functions dominated by massive BCGs, and a deficit of intermediate-mass satellites, while evolving clusters show flatter central lensing signals and an excess of massive satellites. Applying the same selection to IllustrisTNG clusters reproduces these trends and links the observed differences to distinct mass accretion histories. These results demonstrate the close link between cluster galaxy populations and the overall dynamical state of their underlying dark matter halo.

astro-ph.GA↗

arXiv2024

Simulation of thermal conduction by asymmetric dark matter in realistic stars and planets

Dark matter captured in stars can act as an additional heat transport mechanism, modifying fusion rates and asteroseismoloigcal observables. Calculations of heat transport rates rely on approximate solutions to the Boltzmann equation, which have never been verified in realistic stars. Here, we simulate heat transport in the Sun, the Earth, and a brown dwarf model, using realistic radial temperature, density, composition and gravitational potential profiles. We show that the formalism developed in arXiv:2111.06895 remains accurate across all celestial objects considered, across a wide range of kinematic regimes, for both spin-dependent and spin-independent interactions where scattering with multiple species becomes important. We further investigate evaporation rates of dark matter from the Sun, finding that previous calculations appear robust. Our Monte Carlo simulation software Cosmion is publicly available.

hep-ph↗