Probing possible effects of circumgalactic media on the metal content of
  galaxies through the mass-metallicity relationship
  The circumgalactic medium (CGM) connects the gas between the interstellar
medium (ISM) and the intergalactic medium, which plays an important role in
galaxy evolution. We use the stellar mass-metallicity relationship to
investigate whether sharing the CGM will affect the distribution of metals in
galaxy pairs. The optical emission lines from the Sloan Digital Sky Survey Data
Release (SDSS DR7) are used to measure the gas-phase metallicity. We find that
there is no significant difference in the distribution of the metallicity
difference between two members in star forming-star forming pairs ($\rm \Delta
log(O/H)_{diff}$), metallicity offset from the best-fitted stellar
mass-metallicity relationship of galaxies in pairs ($\rm \Delta
log(O/H)_{MS}$), as compared to "fake" pairs. By looking at $\rm \Delta
log(O/H)_{diff}$ and $\rm \Delta log(O/H)_{MS}$ as a function of the star
formation rate (SFR), specific star formation rate (sSFR), and stellar mass
ratio, no difference is seen between galaxies in pairs and control galaxies.
From our results, the share of the CGM may not play an important role in
shaping the evolution of metal contents of galaxies.
