SIMBAD references

One of the surprising results from the Hubble Space Telescope was the discovery that many of the most massive galaxies at redshift z ≈ 2 are very compact, having a half-light radius of only 1-2 kpc. The interpretation is that massive galaxies formed inside out, with their cores largely in place by z ≈ 2 and approximately half of their present-day mass added later through minor mergers. Here we present a compact, massive, quiescent galaxy at a photometric redshift of $zphot=1.94-0.17+0.13{z}_{{{{\rm{phot}}}}}=1.9{4}_{-0.17}^{+0.13}$ with a complete Einstein ring. The ring was found in the James Webb Space Telescope COSMOS-Web survey and is produced by a background galaxy at $zphot=2.98-0.47+0.42{z}_{{{{\rm{phot}}}}}=2.9{8}_{-0.47}^{+0.42}$. Its 1.54″ diameter provides a direct measurement of the mass of the 'pristine' core of a massive galaxy, observed before the mixing and dilution of its stellar population during the 10 Gyr of galaxy evolution between z = 2 and z = 0. We find a mass for the lens $Mlens=6.5-1.5+3.7×1011{M}_{{{{\rm{lens}}}}}=6.{5}_{-1.5}^{+3.7}\times 1{0}^{11}$ M_⊙ within a radius of 6.6 kpc. The stellar mass within the same radius is $Mstars=1.1-0.3+0.2×1011{M}_{{{{\rm{stars}}}}}=1.{1}_{-0.3}^{+0.2}\times 1{0}^{11}$ M_⊙ for a Chabrier initial mass function and the fiducial dark matter mass is $Mdm=2.6-0.7+1.6×1011{M}_{{{{\rm{dm}}}}}=2.{6}_{-0.7}^{+1.6}\times 1{0}^{11}$ M_⊙. Additional mass appears to be needed to explain the lensing results, either in the form of a higher-than-expected dark matter density or a bottom-heavy initial mass function.