Astronomy and Astrophysics
Aims: We use integral field spectroscopic data of four galaxies from the Time Inference with MUSE in Extragalactic Rings (TIMER) survey to explore and compare the kinematics measured in different spectral regions that are sensitive to distinct stellar populations.
Methods: We derive the line-of-sight velocity and velocity dispersion of both a young (≲2 Gyr) and an old stellar population from the spectral regions around the Hβ line and the Ca II Triplet. In addition, we determine colour excess, mean age, and metallicity.
Results: We report a correlation of the colour excess with the difference in the kinematic parameters of the Hβ line and the Ca II Triplet range, which are dominated by young and old stellar populations, respectively. Young stellar populations, located primarily in nuclear rings, have higher velocity dispersions than old ones. These differences in the rings are typically ∼10 km s-1 in velocity dispersion but can have a mean value as high as ∼24 km s-1 in the most extreme case. Trends with age exist in the nuclear rings but are less significant than those with dust extinction. We report different degrees of correlation for these trends among the galaxies in the sample, which are related to the size of the Voronoi bins in their rings. No clear trends for the line-of-sight velocity differences are observed. The absence of these trends can be explained as a consequence of the Hβ line masking process during the kinematic extraction, as confirmed by dedicated simulations.
Conclusions: Our study demonstrates that kinematic differences caused by different stellar populations can be identified in the central regions of nearby galaxies, even from intermediate resolution spectroscopy. This opens the door to future detailed chemo-kinematic studies of galaxies, but also serves as a warning against deriving kinematics from full-spectrum fitting across very wide wavelength ranges when intense star formation is taking place.
Galaxies in the universe can be located in different environments, some of them are isolated or in low density regions and they are usually called field galaxies. The others can be located in galaxy associations, going from loose groups to clusters or even superclusters of galaxies. One of the foremost challenges of the modern Astrophysics is to
We are a large, diverse, and very active research group aiming to provide a comprehensive picture for the formation of galaxies in the Universe. Rooted in detailed stellar population analysis, we are constantly exploring and developing new tools and ideas to understand how galaxies came to be what we now observe.
Our small group is well known and respected internationally for our innovative and important work on various aspects of the structure and evolution of nearby spiral galaxies. We primarily use observations at various wavelengths, exploiting synergies that allow us to answer the most pertinent questions relating to what the main properties of