2023/09/21 by Shengdong Lu, Lu, Shengdong, Kai Zhu +9
Biochemistry, Genetics and Molecular Biology · Computer Science · Physics and Astronomy · #Advanced Fluorescence Microscopy Techniques #Astrophysics of Galaxies (astro-ph.GA) #Blind Source Separation Techniques #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.2309.12395
openalex publication_date 2023/09/21 · openalex created_date 2023/09/26 · openalex updated_date 2026/07/28
Using the final MaNGA sample of 10K galaxies, we investigate the dark matter fraction f\rm DM within one half-light radius R\rm e for about 6K galaxies with good kinematics spanning a wide range of morphologies and stellar velocity dispersion. We employ two techniques to estimate f\rm DM: (i) Jeans Anisotropic Modelling (JAM), which performs dark matter decomposition based on stellar kinematics and (ii) comparing the total dynamical mass-to-light ratios (M/L)\rm JAM and (M∗/L)\rm SPS from Stellar Population Synthesis (SPS). We find that both methods consistently show a significant trend of increasing f\rm DM with decreasing σ\rm e and low f\rm DM at larger σ\rm e. For 235 early-type galaxies with the best models, we explore the variation of stellar initial mass function (IMF) by comparing the stellar mass-to-light ratios from JAM and SPS. We confirm that the stellar mass excess factor α\rm IMF increases with σ\rm e, consistent with previous studies that reported a transition from Chabrier-like to Salpeter IMF among galaxies. We show that the α\rm IMF trend cannot be driven by M∗/L or IMF gradients as it persists when allowing for radial gradients in our model. We find no evidence for the total M/L increasing toward the centre. We detect weak positive correlations between α\rm IMF and age, but no correlations with metallicity. We stack galaxy spectra according to their α\rm IMF to search for differences in IMF-sensitive spectral features (e.g. the \rm Na\rm I doublet). We only find marginal evidence for such differences, which casts doubt on the validity of one or both methods to measure the IMF.