When did round disk galaxies form?
Tomoe M. Takeuchi, Kouji Ohta, Suraphong Yuma, Kiyoto Yabe

TL;DR
This study statistically constrains the epoch when star-forming galaxies transitioned from bar-like to round disk shapes, finding that round disks emerged around redshift z~0.9, indicating a gradual morphological evolution.
Contribution
It provides the first statistical analysis of intrinsic galaxy shapes across redshifts, identifying the epoch of round disk formation using axial ratio distributions.
Findings
Round disk structures emerge around z~0.9.
Intrinsic axial ratios increase with decreasing redshift.
Galaxy shapes evolve gradually from bar-like to round disks.
Abstract
When and how galaxy morphology such as disk and bulge seen in the present-day universe emerged is still not clear. In the universe at , galaxies with various morphology are seen, and star-forming galaxies at show an intrinsic shape of bar-like structure. Then, when did round disk structure form? Here we take a simple and straightforward approach to see the epoch when a round disk galaxy population emerged by constraining the intrinsic shape statistically based on apparent axial ratio distribution of galaxies. We derived the distributions of the apparent axial ratios in the rest-frame optical light ( \AA) of star-forming main sequence galaxies at , , and , and found that the apparent axial ratios of them show peaky distributions at , while a rather flat distribution at the lower redshift. By using a…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
