Numerical simulations of bar formation in the Local Group

Abstract

More than 50 per cent of present-day massive disc galaxies show a rotating stellar bar. Their formation and dynamics have been widely studied both numerically and observationally. Although numerical simulations in the ΛCDM cosmological framework predict the formation of such stellar components, there seems to be a tension between theoretical and observational results. Simulated bars are typically larger in size and have slower pattern speed than observed ones. We study the formation and evolution of barred galaxies, using two ΛCDM zoom-in hydrodynamical simulations of the CLUES project that follow the evolution of a cosmological Local Group-like volume. We found that our simulated bars, at z = 0, are both shorter and faster rotators than previous ones found in other studies on cosmological simulations alleviating the tension mentioned above. These bars match the short tail-end of the observed bar length distribution. In agreement with previous numerical works, we find that bars form in those systems where the disc self-gravity is dominant over the dark matter halo, making them unstable against bar formation. Our bars developed in the last 3–4 Gyr until they achieve their current length and strength; as bars grow, their lengths increase while their rotation speeds decrease. Despite this slowdown, at redshift z = 0 their rotation speeds and size match well the observational data.

Effects of the Central Mass Concentration on Bar Formation in Disk Galaxies

“…Analyses of galaxies in recent simulations of cosmological galaxy formation such as EAGLE and IllustrisTNG, etc. have also found that  ELN is incomplete to predict whether galaxies formed are barred or not (Yurin & Springel 2015;Algorry et al 2017;Izquierdo-Villalba et al 2022;Marioni et al 2022). A recent observational test based on statistically unbiased sample of barred/non-barred galaxies shows that the ELN criterion is largely inaccurate (Romeo et al 2023).…”

Research on the Galaxy Rotation Model based on 21 cm Hydrogen Spectrum

“…The constituent of each planet, the structure, and rotation model within the solar system are already investigated clearly. Some larger scale constructions in the universe, such as the Local Group [2], the Virgo supercluster [3] and the Laniakea supercluster [4], have been detected. As the intermediate object between star systems and these largest constructions, the Galaxy is a very necessary part of the research in this century.…”

The bar rotation rate as a diagnostic of dark matter content in the centre of disc galaxies

“…9) with respect to the observed ones. More recently, the discrepancy between observations and simulations has been attenuated by the findings of Fragkoudi et al ( 2021 ) and Marioni et al ( 2022 ). Fragkoudi et al ( 2021 ) analysed the barred galaxies in the AURIGA simulation suite (Grand et al 2017 ) and showed that they have fast bars because they are more baryon-dominated with respect to those in the TNG simulation.…”

“…Fragkoudi et al ( 2021 ) analysed the barred galaxies in the AURIGA simulation suite (Grand et al 2017 ) and showed that they have fast bars because they are more baryon-dominated with respect to those in the TNG simulation. Marioni et al ( 2022 ) investigated the evolution of barred galaxies in the CLUES simulation (Gottloeber, Hoffman & Yepes 2010 ), which have shorter, but not slower, bars with respect to their observed counterparts. A possible explanation for these findings could reside in the different ingredients of the simulations so far analysed, including the resolution of the simulation and the gas fraction, disc thickness, stellar and AGN feedback, and baryonic content of the simulated galaxies.…”