Dark matter mass loss in galaxy flybys: dependence on impact parameter

Serbian Astronomical Journal

article

Mitrašinović A.¹ 

[1] Astronomical Observatory;Department of Astronomy, Faculty of Mathematics, University of Belgrade

关键词: Galaxies: evolution;    Galaxies: interactions;    Methods: numerical;   

DOI  :  10.2298/SAJ210915001M

来源: Astronomical Observatory, Department of Astronomy, Belgrade

【 摘 要 】

Galaxy flybys, interactions where two independent halos inter-penetrate but detach ata later time and do not merge, occur frequently at lower redshifts. These interactions can significantlyimpact the evolution of individual galaxies - from the mass loss and shape transformation to the emergence of tidal features and formation of morphological disc structures. The main focus of this paper ison the dark matter mass loss of the secondary, intruder galaxy, with the goal of determining a functionalrelationship between the impact parameter and dark matter mass loss. Series of N-body simulations oftypical galaxy flybys (10:1 mass ratio) with differing impact parameters show that the dark matter haloleftover mass of the intruder galaxy follows a logarithmic growth law with impact parameter, regardless of the way the total halo mass is estimated. The lost mass then, clearly, follows the exponentialdecay law. The stellar component stretches faster as the impact parameter decreases, following theexponential decay law with impact parameter. Functional dependence on impact parameter in all casesseems universal, but the fitting parameters are likely sensitive to the interaction parameters and initialconditions (e.g. the mass ratio of interacting galaxies, initial relative velocity of the intruder galaxy,interaction duration). While typical flybys, investigated here, could not be the sole culprit behind theformation of ultra-diffuse or dark matter deficient galaxies, they can still contribute significantly. Rare,atypical and stronger flybys are worth further exploring.

【 授权许可】

CC BY-NC-ND