J/ApJ/898/62 Age & [Z/H] relations of SDSS star-forming galaxies (Barone+, 2020) ================================================================================ Gravitational potential and surface density drive stellar populations. II. Star-forming Galaxies. Barone T.M., D'Eugenio F., Colless M., Scott N. =2020ApJ...898...62B ================================================================================ ADC_Keywords: Galaxies, optical; Spectra, optical; Redshifts; Stars, masses; Abundances Keywords: Scaling relations ; Galaxy stellar content ; Galaxy ages ; Galaxy abundances ; Extragalactic astronomy Abstract: Stellar population parameters correlate with a range of galaxy properties, but it is unclear which relations are causal and which are the result of another underlying trend. In this series, we quantitatively compare trends between stellar population properties and galaxy structural parameters in order to determine which relations are intrinsically tighter, and are therefore more likely to reflect a causal relation. Specifically, we focus on the galaxy structural parameters of mass M, gravitational potential {Phi}~M/R_e_, and surface mass density {Sigma}~M/R_e_^2^. In Barone+ (Paper I; 2018ApJ...856...64B) we found that for early-type galaxies (ETGs) the age-{Sigma} and [Z/H]-{Phi} relations show the least intrinsic scatter as well as the least residual trend with galaxy size. In this work we study the ages and metallicities measured from full spectral fitting of 2085 star-forming galaxies (SFGs) from the SDSS Legacy Survey, selected so all galaxies in the sample are probed to one effective radius. As with the trends found in ETGs, we find that in SFGs age correlates best with stellar surface mass density, and [Z/H] correlates best with gravitational potential. We discuss multiple mechanisms that could lead to these scaling relations. For the [Z/H]-{Phi} relation we conclude that gravitational potential is the primary regulator of metallicity, via its relation to the gas escape velocity. The age-{Sigma} relation is consistent with compact galaxies forming earlier, as higher gas fractions in the early universe cause old galaxies to form more compactly during their in situ formation phase, and may be reinforced by compactness-related quenching mechanisms. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 146 2085 Derived stellar population parameters -------------------------------------------------------------------------------- See also: II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009) V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015) J/ApJ/621/673 : Line indices for 124 early-type galaxies (Thomas+, 2005) J/MNRAS/371/703 : MILES library of empirical spectra (Sanchez-Blazquez+, 2006) J/ApJS/171/146 : Population synthesis in the blue. IV (Schiavon+, 2007) J/MNRAS/382/109 : Massive galaxies in Extended Groth Strip (Trujillo+, 2007) J/MNRAS/404/1639 : MILES base models & new line index system (Vazdekis+, 2010) J/MNRAS/413/813 : ATLAS3D project. I. (Cappellari+, 2011) J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011) J/ApJ/749/121 : Surface brightness profiles if z=2 galaxies (Szomoru+, 2012) J/ApJ/768/74 : PHIBSS: CO obs. of star-forming galaxies (Tacconi+, 2013) J/MNRAS/440/843 : SIM2D parameters of SDSS-DR7 galaxies (Omand+, 2014) J/ApJS/219/8 : SFR for WISE + SDSS spectroscopic galaxies (Chang+, 2015) J/A+A/581/A103 : CALIFA survey across the Hubble sequence (Gonzalez+, 2015) J/MNRAS/448/3484 : ATLAS3D Project. XXX (McDermid+, 2015) J/MNRAS/476/1765 : MaNGA E and S galaxies properties (Li+, 2018) J/ApJ/874/66 : MASSIVE survey. XII. Galaxy gradients (Greene+, 2019) J/ApJ/883/78 : Column densities of CGM absorption lines (Pointon+, 2019) http://www.sdss.org/ : SDSS home page Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 19 I19 --- specObjID SDSS spectroscopic object identifier 21- 39 I19 --- ObjID SDSS photometric object identifier 41- 44 I4 --- Plate [266/2970] SDSS plate identifier 46- 50 I5 d MJD [51609/54592] Modified Julian Date of observation 52- 54 I3 --- Fiber [1/640] SDSS fiber identifier 56- 65 F10.8 --- z [0.043/0.073] SDSS spectroscopic redshift 67- 73 F7.4 [Gyr] logAgeL [-1.33/1.1] log10 luminosity-weighted age 75- 80 F6.4 [Gyr] e_logAgeL [0.05/0.15] Uncertainty in logAgeL 82- 88 F7.4 [-] [Z/H]L [-2.2/0.12] Luminosity-weighted metallicity 90- 95 F6.4 [-] e_[Z/H]L [0.04/0.13] Uncertainty in [Z/H]L 97-102 F6.4 [Gyr] logAgeM [0.03/1.14] log10 mass-weighted age 104-109 F6.4 [Gyr] e_logAgeM [0.0961] Uncertainty in logAge_M 111-117 F7.4 [-] [Z/H]M [-2.11/0.26] Mass-weighted metallicity 119-124 F6.4 [-] e_[Z/H]M [0.1802] Uncertainty in [Z/H]M 126-133 F8.5 [Msun] logM* [9.4/10.4] log10 stellar mass from Kauffmann+ (2003MNRAS.346.1055K) 135-141 F7.5 [Msun] e_logM* [0.05/0.31] Uncertainty in logM* 143-146 F4.2 kpc Re [1.12/2.35] Circularized effective radius in r-band from Simard+ (2011, J/ApJS/196/11) -------------------------------------------------------------------------------- History: From electronic version of the journal References: Barone et al. Paper I. 2018ApJ...856...64B ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 17-Nov-2021