Constraining the interaction history of Arp 269 using stellar population synthesis modelling

Abstract

ABSTRACT We present stellar population synthesis modelling of the nearby interacting galaxy system NGC 4485/90 or Arp 269 using Code Investigating GALaxy Emission. Model results are used to constrain its interaction history and to examine the origin of structures within the system. We have used multiwavelength observations ranging from far-ultraviolet to radio wavelengths to create, model, and fit spectral energy distributions and obtain physical properties of different regions. Our analysis reveals a young and an underlying much older stellar population in both NGC 4485 and 4490. We find the bridge connecting the two galaxies to be formed quite recently, after the second perigalactic encounter between the two. Our analysis shows that the previously identified faint stellar extension associated with NGC 4490 was also formed after the second encounter, which agrees with previous N-body and test-particle simulations. Additionally, we investigate the H i gas distribution in NGC 4485 and find that a mass of H i gas comparable to a dwarf galaxy has been relocated to the south-west part of NGC 4485. This is consistent with the scenario in which the interstellar medium of NGC 4485 is being removed via ram pressure stripping.