We investigate spectroscopic properties of galaxy systems identified based on deep X-ray observations in the COSMOS field .
The COSMOS X-ray system catalog we use ( 37 ) includes 180 X-ray systems to a limiting flux of 1.0 \times 10 ^ { -15 } erg~ { } cm ^ { -2 } ~ { } s ^ { -1 } , an order of magnitude deeper than future e-ROSITA survey .
We identify spectroscopic members of these X-ray systems based on the spectroscopic catalog constructed by compiling various spectroscopic surveys including 277 new measurements ; 137 X-ray systems are spectroscopically identified groups with more than three spectroscopic members .
We identify 1843 spectroscopic redshifts of member candidates in these X-ray systems .
The X-ray luminosity ( L _ { X } ) - velocity dispersion ( \sigma _ { v } ) scaling relation of the COSMOS X-ray systems is consistent with that of massive X-ray clusters .
One of the distinctive features of the COSMOS survey is that it covers the X-ray luminosity range where poor groups overlap the range for extended emission associated with individual quiescent galaxies .
We assess the challenges posed by the complex morphology of the distribution of low X-ray luminosity systems , including groups and individual quiescent galaxies , in the L _ { x } - \sigma _ { v } plane .