Low-redshift compact star-forming galaxies as analogues of high-redshift star-forming galaxies

TL;DR

This study shows that low-redshift compact star-forming galaxies with high emission line equivalent widths closely resemble high-redshift star-forming galaxies in their physical properties, making them valuable proxies for studying early universe galaxies.

Contribution

The paper demonstrates that low-z CSFGs with high EW(Hβ) are excellent analogues of high-z SFGs, extending the understanding of galaxy evolution and properties across cosmic time.

Findings

Low-z CSFGs with EW(Hβ)>100A resemble high-z SFGs in key properties.

Relations between characteristics of CSFGs and high-z SFGs are very similar.

CSFGs can serve as detailed local proxies for distant high-z star-forming galaxies.

Abstract

We compare the relations among various integrated characteristics of ~25,000 low-redshift (z<1.0) compact star-forming galaxies (CSFGs) from Data Release 16 (DR16) of the Sloan Digital Sky Survey (SDSS) and of high-redshift (z>1.5) star-forming galaxies (SFGs) with respect to oxygen abundances, stellar masses M*, far-UV absolute magnitudes M(FUV), star-formation rates SFR and specific star-formation rates sSFR, Lyman-continuum photon production efficiencies (xi_ion), UV continuum slopes \beta, [OIII]5007/[OII]3727 and [NeIII]3868/[OII]3727 ratios, and emission-line equivalent widths EW([OII]3727), EW([OIII]5007), and EW(H\alpha). We find that the relations for low-z CSFGs with high equivalent widths of the H\beta emission line, EW(H\beta)>100A, and high-z SFGs are very similar, implying close physical properties in these two categories of galaxies. Thus, CSFGs are likely excellent proxies for the SFGs in the high-z Universe. They also extend to galaxies with lower stellar masses, down to ~10^6 Msun, and to absolute FUV magnitudes as faint as -14 mag. Thanks to their proximity, CSFGs can be studied in much greater detail than distant SFGs. Therefore, the relations between the integrated characteristics of the large sample of CSFGs studied here can prove very useful for our understanding of high-z dwarf galaxies in future observations with large ground-based and space telescopes.