Leader: Jiwon Chung

Email: jiwon@kasi.re.kr

Collaborators: Hyunjin Jeong, Jong Chul Lee, Joon Hyeop Lee, Kyuseok Oh, Mina Pak (Anyone interested in this subject is welcome to join.)

Topic: The unexpected dynamics of low-mass dwarf galaxies

Status: under review by Science Committee

Abstract: The presence of blue cores in some dwarf early-type galaxies (dE(bc)s) in galaxy clusters suggests the scenario of late-type galaxy infall and subsequent transformation into red, quiescent dEs. Therefore, dE(bc)s are one of the most attractive targets to investigate the nurture effect of the environment on the evolution of galaxies. A few different transformation mechanisms such as ram pressure stripping or galaxy harassment in a cluster for dE(bc)s have been proposed, but none of mechanisms appear to explain all of their observed properties. Meanwhile, our previous studies suggest possibilities that at least some of the dE(bc)s in the Virgo cluster were formed through dwarf–dwarf mergers or tidal interaction in cluster outskirts or filaments before they subsequently fell into the cluster. In this respect, we propose that the local environment might be responsible for the contrasting features in pre-processing of dwarf galaxies found in the filaments and clusters. The maps of ionic abundances and star formation rate can give clues to the formation mechanism of blue-cores in the dwarf early-types. Using Sydney-AAO Multi-object integral-field spectrograph, we recently found the presence of substructures having low metallicity and high star formation in blue-cores for only a few dE(bc)s in filaments and cluster environments, suggesting that infall of low metallicity gas plays a crucial role in forming blue-cores. These dE(bc)s also have extended HI structures and gas-rich compared with other dwarf elliptical galaxies. Since the debate on the evolutionary connection between dwarf galaxies in the clusters and filaments is still ongoing, it is surely worth investigating the chemical and kinematical properties of a large number of dE(bc) samples in the Abell clusters and/or surrounding filamentary structures.

Needed data products: Flux calibrated spectrum, stellar, and ionized gas velocity

Publication Date: 30/09/2023