Properties of Galaxies in Cosmic Filaments around the Virgo Cluster

2021 
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 catalog. The filaments are mainly composed of low-mass, blue dwarf galaxies. We observe that the g - r color of galaxies becomes blue and stellar mass decreases with increasing vertical filament distance. The galaxies were divided into higher-mass (log h^2M_* > 8) and lower-mass (log h^2M_* < 8) subsamples. We also examine the g - r color, stellar mass, Halpha equivalent width (EW(Halpha)), near-ultraviolet (NUV) - r color, and HI fraction distributions of the two subsamples against the vertical distance. The lower-mass galaxies exhibit a negative g - r color gradient, whereas higher-mass galaxies have a flat g - r color distribution. We observe a negative EW(Halpha) gradient for higher-mass galaxies, whereas lower-mass galaxies show no distinct EW(Halpha) variation. In contrast, the NUV - r color distribution of higher-mass galaxies shows no strong trend, whereas the lower-mass galaxies show a 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(Halpha) 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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