Low-redshift compact star-forming galaxies as analogues of high-redshift 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 and of high-redshift (z ≳ 1.5) star-forming galaxies (SFGs) with respect to oxygen abundances, stellar masses M⋆, far-UV absolute magnitudes MFUV, star-formation rates SFR and specific star-formation rates sSFR, Lyman-continuum photon production efficiencies (ξion), UV continuum slopes β, [O III] λ5007/[O II] λ3727 and [Ne III] λ3868/[O II] λ3727 ratios, and emission-line equivalent widths EW([O II] λ3727), EW([O III] λ5007), and EW(Hα). We find that the relations for low-z CSFGs with high equivalent widths of the Hβ emission line, EW(Hβ) ≥ 100 Å, 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 ∼106 M⊙, 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.