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Abstract:
Small-scale structures across a wide range of scales provide a valuable probe of dark matter microphysics. Self-interacting dark matter (SIDM) modifies halo structure through gravothermal evolution, whose outcome depends on the effective scattering strength at the system's characteristic velocity. Depending on this scale, halos can develop extended cores or undergo core contraction, linking observational signatures ranging from dark substructures to galaxy clusters within a dynamical framework. In the presence of two SIDM components, collisional relaxation induces mass segregation, redistributing the species and increasing central halo densities. Our recent work shows that this mechanism can reconcile dwarf-scale cores with cluster constraints while significantly boosting galaxy–galaxy strong lensing efficiencies relative to cold dark matter and one-component SIDM. On smaller scales, strong lensing also probes non-luminous substructures through the analysis of lensing image perturbations and flux ratio anomalies. Recent studies have revealed the presence of compact, dense dark objects that are analogous to core-collapsed SIDM halos. To bridge theory and observation, we have developed an analytic model for lensing by SIDM halos that captures the full range of gravothermal phases and reproduces simulation results at percent-level accuracy. Our recent works have extended the modeling to incorporate the effects of baryons and mass segregation.
Biography:
Daneng Yang received his Ph.D. and bachelor’s degree from Peking University. He previously conducted postdoctoral research at Tsinghua University and the University of California, Riverside. He is currently an Associate Research Professor at Purple Mountain Observatory. In recent years, his research has focused on the distribution of dark matter in the universe and its associated new-physics signatures. His work also broadly covers structure formation, galaxy formation, dark matter detection, and gauge boson production at colliders.
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ID: 477307055