Dust attenuation, bulge formation and inside-out cessation of star-formation in Star-Forming Main Sequence galaxies at z~2.

We derive two-dimensional dust attenuation maps at $\sim1~\mathrm{kpc}$ resolution from the UV continuum for 10 galaxies on the $z\sim2$ Star-Forming Main Sequence (SFMS). Comparison with IR data shows that 9 out of 10 galaxies have no further obscuration in addition to the UV-based correction. The individual rest-frame $V$-band dust attenuation (A$_{\rm V}$) radial profiles scatter around an average profile that gently decreases from $\sim1.8$ mag in the center down to $\sim0.6$ mag at $\sim3-4$ half-mass radii. We use these A$_{\rm V}$ maps to correct UV- and H$\alpha$-based star-formation rates (SFRs), which agree with each other. At masses $\leq10^{11}~M_{\odot}$, the specific SFR (sSFR) profiles are on average radially constant at a mass-doubling timescale of $\sim300~\mathrm{Myr}$, pointing at a synchronous growth of bulge and disk components in such galaxies. At masses $\geq10^{11}~M_{\odot}$, the dust-corrected sSFR profiles are typically centrally-suppressed by a factor of $\sim10$ relative to the galaxy outskirts. With total central obscuration disfavored, this indicates that at least a fraction of massive $z\sim2$ SFMS galaxies have started inside-out their star-formation quenching that will move them to the quenched sequence; this also highlights the key role of progenitor bias effects in the observed evolution of the quenched population. Galaxies above and below the ridge of the SFMS relation have respectively centrally-enhanced and centrally-suppressed sSFRs relative to their outskirts, supporting a picture where bulges are built due to gas `compaction' that leads to a high central SFR as galaxies move towards the upper envelope of SFMS.