Recently, a research achievement completed by Dr. He Zichao of the theoretical astrophysics team of our School, in collaboration with the Purple Mountain Observatory, the National Astronomical Observatories, and Beijing Normal University, among other institutions, was published in the internationally authoritative journal The Astrophysical Journal Letters (ApJL) under the title "Discovery of a Strong-lens Galaxy Pair with the Smallest Projected Separation" (DOI:10.3847/2041-8213/ae82f9). ApJL primarily publishes frontier research findings of significant scientific importance and high timeliness in the fields of astronomy and astrophysics. It is a CAS Zone 1 TOP journal and a JCR Q1 journal, with a latest impact factor of approximately 11. Dr. He Zichao, a faculty member of our School, is the first author of the paper, and Nanchang University is the first affiliated institution.
图 1 Strong gravitational lensing imaging and model reconstruction results of HSC J0233−0205.
The research team independently obtained spectroscopic observation data of this celestial object and conducted detailed scientific analysis, discovering and confirming the strong gravitational lensing system HSC J0233−0205. The two foreground lens galaxies in the system are located at a redshift of 0.79, with an angular separation of only 0.481 arcseconds, corresponding to a projected distance of about 3.6 kiloparsecs. This makes it the system with the smallest projected separation among strong-lens galaxy pairs with reliable observational measurements known to date. Lens modeling indicates that its effective Einstein radius is approximately 1.55 arcseconds, and the projected dark matter mass fraction within the critical curve is about 84%. This system provides a new observational window for studying the redistribution of stars and dark matter during galaxy interactions and merging processes.
This research received strong support from the National Natural Science Foundation of China (NSFC) project and the Telescope Access Program (TAP).
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