2017/10/31 by M. Bernardi, R. K. Sheth, J. -L. Fischer +6 · 1 citation
Physics and Astronomy · #astro-ph.GA #astro-ph.CO
paper · pdf · doi:10.1093/mnras/stx3171
17 pages, 19 figures, 4 tables. Accepted for publication by MNRAS. Tables 1, C1 and C2 are provided as ancillary files
arxiv created 2017/12/15 · arxiv updated 2018/01/31
Spatially resolved kinematics of nearby galaxies has shown that the ratio of dynamical- to stellar population-based estimates of the mass of a galaxy (M_*\rm JAM/M_*) correlates with σe, if M_* is estimated using the same IMF for all galaxies and the stellar M/L ratio within each galaxy is constant. This correlation may indicate that, in fact, the IMF is more dwarf-rich for galaxies with large σ. We use this correlation to estimate a dynamical or IMF-corrected stellar mass, M_*^\rm αJAM, from M* and σe for a sample of 6 × 105 SDSS galaxies for which spatially resolved kinematics is not available. We also compute the `virial' mass estimate k(n,R) Re σR2/G, where n is the Sersic index, in the SDSS and ATLAS\rm 3D samples. We show that an n-dependent correction must be applied to the k(n,R) values provided by Prugniel & Simien (1997). Our analysis also shows that the shape of the velocity dispersion profile in the ATLAS\rm 3D sample varies weakly with n: (σR/σe) = (R/Re)-γ(n). The resulting stellar mass functions, based on M_*^\rm αJAM and the recalibrated virial mass, are in good agreement. If the M_*^\rm αJAM/M_* - σe correlation is indeed due to the IMF, and stellar M/L gradients can be ignored, then our ϕ(M_*^\rm αJAM) is an estimate of the stellar mass function in which σe-dependent variations in the IMF across the population have been accounted for. Using a Fundamental Plane based observational proxy for σe produces comparable results. By demonstrating that cheaper proxies are sufficiently accurate, our analysis should enable a more reliable census of the mass in stars for large galaxy samples, at a fraction of the cost. Our results are provided in tabular form.