sentence1: the x-ray luminosity is a strong function of the temperature , or mass , which means that , eg , foreground groups contribute proportionally less to the x-ray emission than they do to the galaxy surface density .
sentence2: the x-ray luminosity is the 1-40 kev luminosity from ngm97 , but corrected by a factor of two in order to account for the bolometric luminosity likely present in the soft component of the observed x-ray spectrum .