This study uniquely probes the environmental effects on galaxies' star formation by kinematically measuring the mean in-fall time that galaxies have spent in cluster environments at high redshifts spanning a wide range of redshift (0.26 < z < 1.13).

The figure (Figure 8, Kim et al. 2022) shows that galaxies become environmentally quenched (by showing larger Dn4000 strength) as they spent longer time (y-axis) in cluster environments at any luminosity (x-axis). This trend is likely due to longer exposure of cluster galaxies to environmental processes such as the ram pressure and strangulation since cluster in-fall, regardless of galaxy's luminosity (stellar mass).

Thus, the figure shows that environment (which is kinematically measured) and mass are the two key components of galaxy evolution.

Check out the paper for more detail!

We study the dependence of Lyα escape from galaxies on UV continuum size and luminosity using a sample of Green Pea (GP) galaxies, which are the best local analogs of high-redshift Lyα emitters (LAEs). Notably, we found a very compact size of GPs that is similar to those of high-redshift LAEs. Our results show that a compact small size is crucial for escape of Lyα photons, and that Lyα emitters show constant characteristic size independent of their redshift.

We investigate the central bright star-forming regions in a sample of Green Pea galaxies and Lyman Break Galaxy Analogs to understand the relation between Lyα escape and center UV photometric morphology. We found very high star formation intensity (SFI, equivalent to star formation rate surface density (SFRD)) in the central 250 parsec region. Interestingly, while the Lyα equivalent width and the Lyα escape fraction are not significantly correlated with the central SFI, both are significantly correlated with the ratio of SFI to galaxy stellar mass. Based on the results, we suggest a scenario where intense central star formation can drive a galactic wind in galaxies with relatively shallow gravitational potential wells, thus clearing channels for the escape of Lyα photons.

We investigate the relationships between galaxy morphology and stellar properties to understand star formation quenching (suppression) mechanisms at intermediate redshifts. We use a unique set of both photometric and spectroscopic data from the Hubble Space Telescope and obtain 4000 Å break, colors, stellar mass, and morphology. Remarkably, most of quiescent galaxies have a prominent bulge component. However, not all of the bulge-dominated galaxies are quenched. Our results suggest that the presence of a bulge is a necessary but not sufficient requirement for quenching at intermediate redsfhits.

To investigate the detailed stellar properties of galactic bulges, we perform 2D photometric bulge-disk decomposition for a large sample of galaxies drawn from the Sloan Digital Sky Survey. We derive the optical color of bulges from the decomposition and clearly show the systematic trend with Bulge-to-Total luminosity ratio (B/T) in deriving bulge colors. Moreover, we found that bulges exhibit similar scaling relations (i.e., Kormendy and Faber-Jackson relations, and the Fundamental Plane) to those followed by elliptical galaxies, but the bulges in galaxies with lower B/T ratios distinctly show a gradually larger departure in slope from the elliptical galaxy sequence. Our results suggest that the stellar properties and associated formation processes of bulges seem much more diverse than those of elliptical galaxies.