Context. Detecting post-merger features of merger remnants is highly dependent on the depth of observation images. However, there has not been much discussion of how long the post-merger features are visible under different observational conditions. Aims. We investigate a merger-feature time useful for understanding the morphological transformation of galaxy mergers via numerical simulations. Methods. We used N-body/hydrodynamic simulations, including gas cooling, star formation, and supernova feedback. We ran a set of simulations with various initial orbital configurations and with progenitor galaxies having different morphological properties mainly for equal-mass mergers. As reference models, we ran additional simulations for non-equal mass mergers and a merger in a large halo potential. Mock images using the SDSS r band were synthesized to estimate a merger-feature time and compare it between the merger simulations. Results. The mock images suggest that the post-merger features involve a small fraction of stars, and the merger-feature time depends on galaxy interactions. In an isolated environment, the merger-feature time is, on average, ∼2 times the final coalescence time for a shallow surface bright limit of 25 mag arcsec-2. For a deeper surface brightness limit of 28 mag arcsec -2, however, the merger-feature time is a factor of two longer, which is why the detection of post-merger features using shallow surveys has been difficult. Tidal force of a cluster potential is effective in stripping post-merger features out and reduces the merger-feature time. Conclusions.
Bibliographical noteFunding Information:
We thank Volker Spingel for making the Gadget code available to us. S.K.Y. acknowledges support from National Research Foundation of Korea (FY2014). Numerical simulation was performed using the KISTI supercomputer (KSC-2012-C2-11) and the KASI supercomputer. Much of this manuscript was written during the visit of SKY to University of Nottingham and University of Oxford under the travel support by the LG Yon-Am Foundation. We would like to thank the referee for his/her comments that have improved the quality of the original manuscript.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science