February 2-5, 2021

Poster Presentation

Properties of Galaxies in Cosmic Filaments around the Virgo Cluster

Author(s): Youngdae Lee (Chungnam National University), Suk Kim (Chungnam National University), Soo-Chang Rey (Chungnam National University), Jiwon Chung (Korea Astronomy and Space Science Institute)

Presenter: Youngdae Lee (Chungnam National University)

We present the properties of galaxies in filaments around the Virgo cluster with respect to their vertical distance from the filament spine. Using the NASA-Sloan Atlas and group catalogs, we select galaxies that do not belong to groups in filaments. The filament member galaxies are then defined as those located within 3.5 scale length from the filament spine. The filaments are mainly (~87%) composed of low-mass dwarf galaxies of logM∗/M⊙ < 9 dominantly located on the blue cloud in color-magnitude diagrams. We observe that the g − r color and stellar mass of galaxies correlate with their vertical distance from the filament spine in which the color becomes red and stellar mass decreases with increasing vertical filament distance. The galaxies were divided into two subsamples in different stellar mass ranges, with lower-mass (logM∗/M⊙ ≤ 8) galaxies showing a clear negative g−r color gradient, whereas higher-mass (logM∗/M⊙ > 8) galaxies have a flat distribution against the vertical filament distance. We observe a negative EW(Hα) gradient for higher-mass galaxies, whereas lower-mass galaxies show no distinct variation in EW(Hα) against the vertical filament distance. In contrast, the NUV − r color distribution of higher-mass galaxies shows no strong dependence on the vertical filament distance, whereas the lower-mass galaxies show a distinct negative NUV − r color gradient. We do not witness clear gradients of HI fraction in either the higher- or lower-mass subsamples. We propose that the negative color and stellar mass gradients of galaxies can be explained by mass assembly from past galaxy mergers at different vertical filament distances. In addition, galaxy interactions might be responsible for the contrasting features of EW(Hα) and NUV − r color distributions between the higher- and lower-mass subsamples. The HI fraction distributions of the two subsamples suggest that ram-pressure stripping and gas accretion could be ignorable processes in the Virgo filaments.

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