Environmental Influences on Star Formation in Low-mass Galaxies Observed by the SDSS-IV/MaNGA Survey

Abstract

Abstract We explore the environmental influences on the star formation (SF) in low-mass galaxies with stellar mass 8 ≤ log(M ⋆/M ⊙) ≤ 10 at a redshift of 0.01 < z < 0.07. We identify the neighboring galaxies for our sample using the spectroscopically observed galaxies in the Sloan Digital Sky Survey (SDSS). Our 287 selected pair candidates have a neighboring galaxy with a stellar mass ratio of M Neighbor/M Candidate ≤ 4 at a projected separation within d proj ≤ 1500 kpc and a line-of-sight kinematic separation of Δv LOS ≤ 300 km s−1. Our control galaxies are isolated from other galaxies within a projected radius of 1500 kpc. All selected galaxies in our sample are spectroscopically observed by the fourth generation of SDSS/Mapping Nearby Galaxies at Apache Point Observatory (SDSS-IV/MaNGA) integral field spectroscopy survey. We radially bin our selected galaxies into three regions with a radial distance of 0 ≤ R/R e ≤ 0.5 (inner), 0.5 ≤ R/R e ≤ 1.0 (middle), and 1.0 ≤ R/R e ≤ 1.5 (outer), in which R e is the effective radius at where the galaxy emit half of its light. We conclude that the SF activities in low-mass galaxies are affected by their environmental conditions when Δv LOS ≤ 100 km s−1 at d proj ≤ 400 kpc. We use stellar-mass-weighted SF rate surface density ( ) to describe the SF strength in each radially binned region. For the pair candidates with 0.25 ≤ M Neighbor/M Candidate ≤ 4 at d proj ≤ 100 kpc and , we observe an SF enhancement of ( = / ) in their inner regions, which decreases with increasing galactic radii.