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

Abstract

We derive two-dimensional dust attenuation maps at $\sim 1\mathrm{kpc}$ resolution from the UV continuum for ten galaxies on the $z\sim 2$ Star-Forming Main Sequence (SFMS). Comparison with IR data shows that 9 out of 10 galaxies do not require further obscuration in addition to the UV-based correction, though our sample does not include the most heavily obscured, massive galaxies. The individual rest-frame $V$-band dust attenuation (A${}_{\mathrm{V}}$) radial profiles scatter around an average profile that gently decreases from $\sim 1.8$ mag in the center down to $\sim 0.6$ mag at $\sim 3-4$ half-mass radii. We use these maps to correct UV- and H$\hat{I}\pm$-based star-formation rates (SFRs), which agree with each other. At masses $<10^{11}{M}_{\mathrm{sun}}$, the dust-corrected specific SFR (sSFR) profiles are on average radially constant at a mass-doubling timescale of $\sim 300\mathrm{Myr}$, pointing at a synchronous growth of bulge and disk components. At masses $>10^{11}{M}_{\mathrm{sun}}$, the sSFR profiles are typically centrally-suppressed by a factor of $\sim 10$ relative to the galaxy outskirts. With total central obscuration disfavored, this indicates that at least a fraction of massive $z\sim 2$ SFMS galaxies have started their inside-out star-formation quenching that will move them to the quenched sequence. In combination with other observations, 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.

26 pages, 15 figures (incl. appendix); accepted by ApJ