Mon. Not. R. Astron. Soc., 427, 906-918 (2012/December-1)
Scaling relations of metallicity, stellar mass and star formation rate in metal-poor starbursts – I. A fundamental plane.
HUNT L., MAGRINI L., GALLI D., SCHNEIDER R., BIANCHI S., MAIOLINO R., ROMANO D., TOSI M. and VALIANTE R.
Abstract (from CDS):
Most galaxies follow well-defined scaling relations of metallicity (O/H), star formation rate (SFR) and stellar mass (Mstar). However, low-metallicity starbursts, rare in the Local Universe but more common at high redshift, deviate significantly from these scaling relations. On the `main sequence' of star formation, these galaxies have high SFR for a given Mstar; and on the mass–metallicity relation, they have excess Mstar for their low metallicity. In this paper, we characterize O/H, Mstar and SFR for these deviant `low-metallicity starbursts', selected from a sample of ∼ 1100 galaxies, spanning almost two orders of magnitude in metal abundance, a factor of ∼ 106 in SFR, and of ∼ 105 in stellar mass. Our sample includes quiescent star-forming galaxies and blue compact dwarfs at redshift 0, luminous compact galaxies at redshift 0.3, and Lyman break galaxies at redshifts 1–3.4. Applying a principal component analysis (PCA) to the galaxies in our sample with Mstar ≤ 3 x 1010M☉ gives a Fundamental Plane (FP) of scaling relations; SFR and stellar mass define the plane itself, and O/H its thickness. The dispersion for our sample in the edge-on view of the plane is 0.17dex, independently of redshift and including the metal-poor starbursts. The same FP is followed by 55100 galaxies selected from the Sloan Digital Sky Survey, with a dispersion of 0.06dex. In a companion paper, we develop multi-phase chemical evolution models that successfully predict the observed scaling relations and the FP; the deviations from the main scaling relations are caused by a different (starburst or `active') mode of star formation. These scaling relations do not truly evolve, but rather are defined by the different galaxy populations dominant at different cosmological epochs.
© 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS
galaxies: abundances - galaxies: dwarf - galaxies: evolution - galaxies: high-redshift - galaxies: starburst - galaxies: star formation
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