The structural properties of classical bulges and discs from z~2
  We study the rest-frame optical mass-size relation of bulges and discs from
z~2 to z~0 for a complete sample of massive galaxies in the CANDELS fields
using 2 component S\'ersic models (Dimauro et a. 2018). Discs and star forming
galaxies follow similar mass-size relations. The mass-size relation of bulges
is less steep than the one of quiescent galaxies (best fit slope of ~ 0.7 for
quiescent galaxies against ~ 0.4 for bulges). We find little dependence of the
structural properties of massive bulges and discs with the global morphology of
galaxies (disc vs. bulge dominated) and the star formation activity
(star-forming vs. quiescent). This result suggests similar bulge formation
mechanisms for most massive galaxies and also that the formation of the bulge
component does not significantly affect the disc structure. Our findings pose a
challenge to models envisioning multiple channels for massive bulge growth,
such as disc instabilities and mergers.
