SPARC: Mass Models for 175 Disk Galaxies with Spitzer Photometry and Accurate Rotation Curves (original) (raw)

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Abstract

We introduce SPARC (Spitzer Photometry and Accurate Rotation Curves): a sample of 175 nearby galaxies with new surface photometry at 3.6 μm and high-quality rotation curves from previous H I/Hα studies. SPARC spans a broad range of morphologies (S0 to Irr), luminosities (∼5 dex), and surface brightnesses (∼4 dex). We derive [3.6] surface photometry and study structural relations of stellar and gas disks. We find that both the stellar mass-H I mass relation and the stellar radius-H I radius relation have significant intrinsic scatter, while the H I mass-radius relation is extremely tight. We build detailed mass models and quantify the ratio of baryonic to observed velocity (V bar/V obs) for different characteristic radii and values of the stellar mass-to-light ratio (ϒ⋆) at [3.6]. Assuming ϒ⋆ ≃ 0.5 M ☉/L ☉ (as suggested by stellar population models), we find that (I) the gas fraction linearly correlates with total luminosity (II) the transition from star-dominated to gas-dominated galaxies roughly corresponds to the transition from spiral galaxies to dwarf irregulars, in line with density wave theory; and (III) V bar/V obs varies with luminosity and surface brightness: high-mass, high-surface-brightness galaxies are nearly maximal, while low-mass, low-surface-brightness galaxies are submaximal. These basic properties are lost for low values of ϒ⋆ ≃ 0.2 M ☉/L ☉ as suggested by the DiskMass survey. The mean maximum-disk limit in bright galaxies is ϒ⋆ ≃ 0.7 M ☉/L ☉ at [3.6]. The SPARC data are publicly available and represent an ideal test bed for models of galaxy formation.

Publication:

The Astronomical Journal

Pub Date:

December 2016

DOI:

10.3847/0004-6256/152/6/157

10.48550/arXiv.1606.09251

arXiv:

arXiv:1606.09251

Bibcode:

2016AJ....152..157L

Keywords:

E-Print:

Accepted for publication in AJ (14 pages, 8 figures). All data are available at http://astroweb.cwru.edu/SPARC/