High-order stellar kinematics in MaNGA integral-field spectroscopy survey: classification, stellar population, and the impact of galaxy bars and mergers

ABSTRACT We extract with ppxf and analyse the high-order stellar kinematic moments $h_{\rm 3}$ (related to skewness) and $h_{\rm 4}$ (related to kurtosis) in a complete subsample of 2230 galaxies with well-sampled line-of-sight velocity distributions ($\sigma _{\rm e} \gtrsim 140\, \mathrm{km\,s^{-1}}$) from the final data release of 10 010 unique galaxies of the MaNGA survey. To reduce template mismatch, we created a stellar library based on MaStar. We used proxies for the specific angular momentum parameter ($\lambda _{R_\mathrm{e}}$) and ellipticity ($\varepsilon$) to distinguish between fast and slow rotators. Using the Pearson correlation coefficient between spatially resolved $h_3$ and $V/\sigma$ within the isophotes of 2.5 half-light radii ($R_{\rm e}$), we classified 1599 fast rotators into (i) 1073 galaxies showing a strong $h_3$ versus $V/\sigma$ anticorrelation, indicative of normal rotating stellar discs as observed in earlier studies, and (ii) 526 galaxies exhibiting weak or no correlation between $h_3$ and $V/\sigma$. These galaxies are likely disturbed, showing signs of bars or merging. Further inspection revealed that 85 galaxies from the latter group contain an anticorrelated inner disc, with half of these inner discs composed of younger stellar populations, indicative of recent gas accretion and nuclear star formation. This catalogue presents measurements of high-order stellar kinematic moments, providing a basis for exploring their potential links with the kinematic structures of galaxies. We have made the newly extracted high-order kinematics publicly available for further studies on stellar dynamics and galaxy formation.