CDM and SIDM Interpretations of the Strong Gravitational Lensing Object JWST-ER1

Abstract

van Dokkum et al. (arXiv:2309.07969) reported the discovery of JWST-ER1, a strong lensing object at redshift $z\approx2$, using data from the James Webb Space Telescope. The lens mass within the Einstein ring is $5.9$ times higher than the expected stellar mass from a Chabrier initial mass function, indicating a high dark matter density. In this work, we show that a cold dark matter halo, influenced by gas-driven adiabatic contraction, can account for the observed lens mass. We interpret the measurement of JWST-ER1 in the self-interacting dark matter scenario and show that the cross section per particle mass $\sigma/m\approx0.1~{\rm cm^2/g}$ is generally favored. Intriguingly, $\sigma/m\approx0.1~{\rm cm^2/g}$ can also be consistent with the strong lensing observations of early-type galaxies at redshift $z\approx0.2$, where adiabatic contraction is not observed overall.