Study of stellar mass and concentration impact on color void paired galaxies. (a) Central panel: Scatter plot of u − r as a function of log(M_*/M_sun) for pair galaxies in voids (blue), in wall (green), and in fields (black). Diamonds and solid lines indicate the median. The vertical dotted line represents log(M_*/M_sun)=9.5. Left panel: Normalized distribution of g − r for log(M_*/M_sun)< 9.5 paired galaxies in voids and field. Right panel: Same as in the left panel but for log(M_*/M_sun)> 9.5. (b) Central panel: Scatter plot of u − r as a function of concentration index for pair galaxies in voids (blue), in wall (green) and in fields (black). Diamonds and solid lines indicate the median. Left panel: Normalized distribution of g − r for C <  2.5 paired galaxies in voids and field. Right panel: Same as in the left panel but for C >  2.5. (c) Central panel: Scatter plot of g − r as a function of log(M_*/M_sun) for pair galaxies in voids (blue), in wall (green), and in fields (black). Diamonds and solid lines indicate the median. The vertical dotted line represents log(M_*/M_sun)=9.5. Left panel: Normalized distribution of g − r for log(M_*/M_sun)< 9.5 paired galaxies in voids and field. Right panel: Same as in the left panel but for log(M_*/M_sun)> 9.5. (d) Central panel: Scatter plot of g − r as a function of concentration index for pair galaxies in voids (blue), in wall (green), and in fields (black). Diamonds and solid lines indicate the median. Left panel: Normalized distribution of g − r for C <  2.5 paired galaxies in voids and field. Right panel: Same as in the left panel but for C >  2.5.