# Inside-out growth in the early Universe: a core in a vigorously star-forming disc

**Authors:** William M. Baker, Sandro Tacchella, Benjamin D. Johnson, Erica Nelson, Katherine A. Suess, Francesco D'Eugenio, Mirko Curti, Anna de Graaff, Zhiyuan Ji, Roberto Maiolino, Brant Robertson, Jan Scholtz, Stacey Alberts, Santiago Arribas, Kristan Boyett, Andrew J. Bunker, Stefano Carniani, Stephane Charlot, Zuyi Chen, Jacopo Chevallard  
**arXiv:** [2306.02472](https://arxiv.org/abs/2306.02472)  
**Date:** 2023-06-04  
**Summary page:** https://www.summarizepaper.com/en/paper/2306.02472v1/

## Key points

- Study focuses on physical processes contributing to morphological evolution and structural diversity of galaxies
- Researchers present findings on galaxy JADES-GS+53.18343-27.79097
- JADES-GS+53.18343-27.79097 is a star-forming galaxy with three distinct components: compact core, star-forming disc, and star-forming clump
- Central stellar mass density comparable to most massive elliptical galaxies observed today, despite being 1000 times less massive overall
- JADES-GS+53.18343-27.79097 may represent an early stage in formation and growth process of massive elliptical galaxies
- Specific star formation rate increases towards the outskirts of JADES-GS+53.18343-27.79097, indicating inside out growth pattern during Epoch of Reionization (EoR)
- Findings provide evidence for inside out growth in early galaxies and shed light on mechanisms responsible for morphological evolution and structural diversity during this cosmic period

## Summary

This study focuses on the physical processes that contribute to the morphological evolution and structural diversity of galaxies, which are still poorly understood in extragalactic astrophysics. The researchers present their findings on a particularly interesting galaxy called JADES-GS+53.18343-27.79097, which existed during the first 700 million years of the Universe's history. JADES-GS+53.18343-27.79097 is a star-forming galaxy with a stellar mass of $10^{8.6}$ solar masses and consists of three distinct components: a highly compact core with a half-light radius of 144 parsecs, a strongly star-forming disc with a radius of 468 parsecs, and a star-forming clump. Each component exhibits unique star formation histories. The central stellar mass density of this galaxy is found to be within a factor of two of the most massive elliptical galaxies observed in the present day Universe, despite being globally 1000 times less massive overall. This suggests that JADES-GS+53.18343-27.79097 may represent an early stage in the formation and growth process of massive elliptical galaxies. Furthermore, it is observed that the specific star formation rate increases significantly towards the outskirts of JADES-GS+53.18343-27.79097, indicating an inside out growth pattern for this galaxy during the Epoch of Reionization (EoR). These findings provide strong evidence for inside out growth in early galaxies and shed light on mechanisms responsible for morphological evolution and structural diversity in galaxies during this crucial period in cosmic history.