"This illustrated map of the universe shows galaxy group EGS77 clearing away the cosmic fog of the early universe, some 13 billion years ago."
This is a very interesting, detailed study using spectra and determining the redshift, z=7.7. The Friedman-Lematrie model for the expanding universe can be found at these cosmology calculators, https://ned.ipac.caltech.edu/help/cosmology_calc.html
A very detailed report is found here too, Onset of Cosmic Reionization: Evidence of An Ionized Bubble Merely 680 Myrs after the Big Bang
The Abstract reports, "While most of the inter-galactic medium (IGM) today is permeated by ionized hydrogen, it was largely filled with neutral hydrogen for the first 700 million years after the Big Bang. The process that ionized the IGM (cosmic reionization) is expected to be spatially inhomogeneous, with fainter galaxies playing a significant role. However, we still have only a few direct constraints on the reionization process. Here we report the first spectroscopic confirmation of two galaxies and very likely a third galaxy in a group (hereafter EGS77) at redshift z = 7.7, merely 680 Myrs after the Big Bang. The physical separation among the three members is < 0.7 Mpc. We estimate the radius of ionized bubble of the brightest galaxy to be about 1.02 Mpc, and show that the individual ionized bubbles formed by all three galaxies likely overlap significantly, forming a large yet localized ionized region, which leads to the spatial inhomogeneity in the reionization process. It is striking that two of three galaxies in EGS77 are quite faint in the continuum, thanks to our selection of reionizing sources using their Lyman-alpha line emission. Indeed, one is the faintest spectroscopically confirmed galaxy yet discovered at such high redshifts. Our observations provide direct constraints in the process of cosmic reionization, and allow us to investigate the properties of sources responsible for reionizing the universe. "
The Abstract also contains the large, arXiv full report too. Impressive spectroscopic work to determine z=7.7 and Einstein GR using the Friedman-Lematrie metrics for distance in the expanding universe model. At z=7.7, the look back time distance is some 13E+9 light years distance but the objects actual distance in the Big Bang model is some 29.521E+9 light years distance according to the F-L metric based upon Einstein GR.