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

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 ( ${\rm{\Sigma }}\mathrm{SFR}/{M}_{\star }$ ) 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 ${\rm{\Delta }}{V}_{\mathrm{LOS}}\leqslant 100\,\mathrm{km}\,{{\rm{s}}}^{-1}$ , we observe an SF enhancement of ${f}_{{\rm{\Delta }}\mathrm{SF}}=1.75\pm 0.96$ ( ${f}_{{\rm{\Delta }}\mathrm{SF}}$ = $[{({\rm{\Sigma }}\mathrm{SFR}/{M}_{\star })}_{\mathrm{Pair}}-{({\rm{\Sigma }}\mathrm{SFR}/{M}_{\star })}_{\mathrm{Control},\mathrm{mean}}]$ / ${({\rm{\Sigma }}\mathrm{SFR}/{M}_{\star })}_{\mathrm{Control},\mathrm{mean}}$ ) in their inner regions, which decreases with increasing galactic radii.