Oral Presentation

Understanding the cause of diverse rotation curves of nearby galaxies with cosmological hydrodynamical simulations

Author(s): Daeun Jeong , Ho Seong Hwang (Seoul National University)

Presenter: Daeun Jeong (Seoul National University)

Recent integral field spectroscopic observations of galaxies have shown that the radial dependence of galaxy rotation is very diverse. To better understand the physical origin of this diversity, we analyze the cosmological hydrodynamic simulation data of IllustrisTNG. We use the galaxies with 9.4 < log(Mstar/M☉) < 11.5 to make a sample comparable to that of observations, and adopt two methods to determine the shape of rotation curves. First, we construct the mock line-of-sight velocity IFU data and conduct 2D fitting to determine the rotational velocity and the slope of the rotation curve in the outer region. Secondly, we convert the enclosed mass at each galactocentric radius into the circular velocity to obtain similar physical parameters. The outer slopes of the simulated galaxies show diverse patterns, which are consistent with observational results. We examine the relation between the outer slope and the galaxy properties, and successfully reproduce the observed dependence of the outer slope on stellar mass and morphology. The outer slope decreases as galaxies are more massive in terms of stellar mass, and increases as galaxies are more disky. The outer slope of the rotation curves seems to be affected by galaxy environments, which are closely related to the dark matter and baryonic matter distributions of the galaxies.