TY - JOUR
T1 - Avid
T2 - Formation and evolution of a coalesced major merger of late-type dwarf galaxies (VCC 479) on the outskirts of the Virgo cluster
AU - Sun, Weibin
AU - Zhang, Hong-Xin
AU - Smith, Rory
AU - Brinks, Elias
AU - Côté, Patrick
AU - Oh, Se-Heon
AU - Lin, Zesen
AU - Boselli, Allessandro
AU - Ferrarese, Laura
AU - Li, Fujia
AU - Sun, Yuzhu
AU - Chen, Lijun
AU - Zhang, Lanyue
AU - Kim, Minsu
AU - Kim, Jaebeom
AU - Li, Tie
AU - Tao, Bojun
AU - Taylor, Matt
AU - Duc, Pierre-Alain
AU - Sánchez-Janssén, Ruben
AU - Zhao, Yinghe
AU - Paudel, Sanjaya
AU - Peng, Eric W.
AU - Wang, Kaixiang
AU - Gwyn, Stephen
AU - Fossati, Matteo
AU - Cuillandre, Jean-Charles
N1 - 18 pages, 15 figures. Accepted for Publication in A&A
PY - 2025/6/17
Y1 - 2025/6/17
N2 - Dwarf-dwarf galaxy mergers are among the least explored aspects of dwarf galaxy pre-processing as they fall into clusters. We present the first case study of a coalesced late-type dwarf major merger (VCC 479; stellar mass $\sim\,8\,\times\,10^7\,\rm M_\odot$) that has undergone significant environmental influence, with the aim of exploring dwarf galaxy evolution under the combined effects of galaxy interactions and environmental processes, and understanding its relevance to the diversity of dwarf galaxies in cluster environments. Our analysis is based on VLA and FAST HI emission line mapping from the Atomic gas in Virgo Interacting Dwarf galaxies (AVID) survey. We also perform idealized hydrodynamical simulations of dwarf-dwarf mergers to help interpret the observations. We identify symmetric stellar shell structures in VCC 479, indicative of a coalesced major merger of dwarf galaxies. The galaxy features a central starburst, initiated $\sim$600 Myr ago, embedded within an exponential disk quenched $\sim$1 Gyr ago. The starburst contributes only 2.9$\pm$0.5\% of the total stellar mass, and VCC 479's global star formation rate is 0.3 dex lower than typical dwarfs of similar mass. The galaxy is highly HI deficient, with most HI gas concentrated within the central 1 kpc and little extended HI envelope. The misalignment of the HI velocity field with the stellar body is best explained by merger-triggered gas inflow, as seen in our simulations. Our analysis is consistent with a scenario that the majority of HI gas of the progenitor galaxies was removed by the cluster environment prior to the final coalescence. The merger concentrates the remaining gas toward the galaxy center, triggering a central starburst. The combined effect of environment stripping and galaxy merger has transformed VCC 479 into a blue-core dwarf undergoing morphological transition from a late-type to an early-type galaxy.
AB - Dwarf-dwarf galaxy mergers are among the least explored aspects of dwarf galaxy pre-processing as they fall into clusters. We present the first case study of a coalesced late-type dwarf major merger (VCC 479; stellar mass $\sim\,8\,\times\,10^7\,\rm M_\odot$) that has undergone significant environmental influence, with the aim of exploring dwarf galaxy evolution under the combined effects of galaxy interactions and environmental processes, and understanding its relevance to the diversity of dwarf galaxies in cluster environments. Our analysis is based on VLA and FAST HI emission line mapping from the Atomic gas in Virgo Interacting Dwarf galaxies (AVID) survey. We also perform idealized hydrodynamical simulations of dwarf-dwarf mergers to help interpret the observations. We identify symmetric stellar shell structures in VCC 479, indicative of a coalesced major merger of dwarf galaxies. The galaxy features a central starburst, initiated $\sim$600 Myr ago, embedded within an exponential disk quenched $\sim$1 Gyr ago. The starburst contributes only 2.9$\pm$0.5\% of the total stellar mass, and VCC 479's global star formation rate is 0.3 dex lower than typical dwarfs of similar mass. The galaxy is highly HI deficient, with most HI gas concentrated within the central 1 kpc and little extended HI envelope. The misalignment of the HI velocity field with the stellar body is best explained by merger-triggered gas inflow, as seen in our simulations. Our analysis is consistent with a scenario that the majority of HI gas of the progenitor galaxies was removed by the cluster environment prior to the final coalescence. The merger concentrates the remaining gas toward the galaxy center, triggering a central starburst. The combined effect of environment stripping and galaxy merger has transformed VCC 479 into a blue-core dwarf undergoing morphological transition from a late-type to an early-type galaxy.
KW - astro-ph.GA
M3 - Article
SN - 0004-6361
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
ER -