We present the Kormendy and mass-size relations for early-type galaxies ( ETGs ) as a function of environment at z \sim 1.3 .
Our sample includes 76 visually classified ETGs with masses 10 ^ { 10 } < M / M _ { \sun } < 10 ^ { 11.5 } , selected in the Lynx supercluster and in the GOODS/CDF-S field , 31 ETGs in clusters , 18 in groups and 27 in the field , all with multi-wavelength photometry and HST /ACS observations .
The Kormendy relation , in place at z \sim 1.3 , does not depend on the environment .
The mass-size relation reveals that ETGs overall appear to be more compact in denser environments : cluster ETGs have sizes on average around 30-50 % smaller than those of the local universe , and a distribution with a smaller scatter , whereas field ETGs show a mass-size relation with a similar distribution than the local one .
Our results imply that ( 1 ) the mass-size relation in the field did not evolve overall from z \sim 1.3 to present ; this is interesting and in contrast to the trend found at higher masses from previous works ; ( 2 ) in denser environments , either ETGs have increased their size by 30-50 % , on average , and spread their distributions , or more ETGs have been formed within the dense environment from not ETG progenitors or larger galaxies have been accreted to a pristine compact population to reproduce the mass-size relation observed in the local Universe .
Our results are driven by galaxies with masses M \lesssim 2 \times 10 ^ { 11 } M _ { \sun } and those with masses M \sim 10 ^ { 11 } M _ { \sun } follow the same trends that the entire sample .
Following Valentinuzzi et al .
definition of superdense ETGs , around 35-45 % of our cluster sample is made of superdense ETGs .