2015/02/03 by A. Renzini, Alvio Renzini, Yingjie Peng · 9 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Elliptical galaxy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Normalization (sociology) #Physics #Star (game theory) #Star formation #Stellar mass #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1088/2041-8205/801/2/l29
published as 2015, ApJ, 801, L29 · Accepted for publication in ApJ Letters
arxiv created 2015/02/03 · openalex publication_date 2015/03/12 · arxiv updated 2015/03/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
The main sequence (MS) of star-forming (SF) galaxies plays a fundamental role in driving galaxy evolution and our efforts to understand it. However, different studies find significant differences in the normalization, slope, and shape of the MS. These discrepancies arise mainly from the different selection criteria adopted to isolate SF galaxies, which may include or exclude galaxies with a specific star formation rate (SFR) substantially below the MS value. To obviate this limitation of all current criteria, we propose an objective definition of the MS that does not rely at all on a pre-selection of SF galaxies. Constructing the 3D SFR–mass–number plot, the MS is then defined as the ridge line of the SF peak, as illustrated with various figures. The advantages of such a definition are manifold. If generally adopted, it will facilitate the inter-comparison of results from different groups using the same SFR and stellar mass diagnostics, or it will highlight the relative systematics of different diagnostics. All of this could help to understand MS galaxies as systems in a quasi-steady state equilibrium and would also provide a more objective criterion for identifying quenching galaxies.