Numerical modelling of the vertical structure and dark halo parameters in disc galaxies

Abstract

A. Khoperskov et al.: Numerical modelling of disc galaxies Astron. Nachr./AN XXX (200X) XThe non-linear dynamics of bending instability and vertical structure of a galactic stellar disc embedded into a spherical halo are studied with N-body numerical modelling. Development of the bending instability in stellar galactic disc is considered as the main factor that increases the disc thickness. Correlation between the disc vertical scale height and the halo-to-disc mass ratio is predicted from the simulations. The method of assessment of the spherical-todisc mass ratio for edge-on spiral galaxies with a small bulge is considered. Modelling of eight edge-on galaxies: NGC 891, NGC 4738, NGC 5170, UGC 6080, UGC 7321, UGC 8286, UGC 9422 and UGC 9556 is performed. Parameters of stellar discs, dark haloes and bulges are estimated. The lower limit of the dark-toluminous mass ratio in our galaxies is of the order of 1 within the limits of their stellar discs. The dark haloes dominate by mass in the galaxies with very thin stellar discs (NGC 5170, UGC 7321 and UGC 8286).

Gravitational stability and dynamical overheating of galactic stellar disks

“…Second, the assumption of disk marginal stability enables to explain a positive correlation of relative disks thicknesses and their relative masses within the optical borders ). Note, however, that both numerical simulations (Sotnikova, Rodionov (2006), Khoperskov et al (2010)) and the analysis of observations of edge-on galaxies (Mosenkov et al (2010), Bizyaev, Mitronova (2009), Bizyaev (2010)) show that this correlation is rather sparse especially for galaxies with small bulges. Moreover, numerical dynamical models by far are not always compatible with the assumption of disk marginal stability (see, e.g., ).…”

New Features of Parallel Implementation of N-Body Problems on GPU

“…According to this model iterative procedure of the disk initial conditions generation is described in Ref. [1,15,18]. Note that, in such model, the stellar disk is completely self-gravitating, and the following analysis provides an upper limit for numerical errors in direct N-body integration.…”

The Tully–Fisher relation for flat galaxies

“…The existence of superthin galaxies with a/b 10 is possible only in the presence of massive dark halos around galaxies (Bizyaev et al 2017). Using N-body simulations, Zasov et al (1991); Sotnikova & Rodionov (2006); Khoperskov et al (2010) show that theoretical relationship between the thickness of disc galaxies and the mass of their spherical components allows one to estimate the lower limit for the dark halo mass in galaxies. The latter may affect the TF relation, which encourages us to consider the relative thickness of galactic discs as an additional parameter in the TF relation.…”