Joule–Thomson expansion and images of black hole in SU(N)-non-linear sigma model

Abstract

AbstractWe consider recently constructed black holes in the Einstein SU(N)-non-linear sigma model and study the Joule–Thomson expansion and observable characteristics. We calculate Joule–Thomson coefficient, inversion curves and isenthalpic curves to investigate the heating and cooling phases in $$T-P$$ T - P plane of the considered model. Our findings reveal distinct behavior of these black holes different from those reported in existing studies. Notably, inversion curves vanish in the heating regions, resulting in the black holes consistently remaining in the cooling phase. Additionally, we investigate the impact of the flavor number N on the Joule–Thomson expansion of these black holes. We observe that employing higher values of enthalpy and flavor number N extends the ranges of isenthalpic and inversion curves but the black holes remain in cooling phase. We also study the shadow and visual characteristics of the these black hole focusing on its illumination by two theoretical models of static accretion. We analyze that higher flavor numbers have high peaks of observed intensities and it shifts to smaller impact parameter which leads to smaller images.