We combine high-resolution ALMA and HST /CANDELS observations of 20 submillimeter galaxies ( SMGs ) predominantly from the AS2UDS survey at z \simeq 2 with bright rest-frame optical counterparts ( K _ { s } \lesssim 22.9 ) to investigate the resolved structural properties of their dust and stellar components .
We derive two-dimensional stellar-mass distributions that are inferred from spatial mass-to-light ratio ( M / L ^ { \ast } ) corrections based on rest-frame optical colors .
Due to the high central column densities of dust in our SMGs , our mass distributions likely represent a lower limit to the true central mass density .
The centroid positions between the inferred stellar-mass and the dust distributions agree within 1.1 kpc , indicating an overall good spatial agreement between the two components .
The majority of our sources exhibit compact dust configurations relative to the stellar component ( with a median ratio of effective radii R _ { { e,dust } } / R _ { { e,* } } = 0.6 ) .
This ratio does not change with specific star-formation rate ( sSFR ) over the factor of 30 spanned by our targets , sampling the locus of ‘ normal ’ main sequence galaxies up to the starburst regime , \log { ( { { sSFR / sSFR _ { MS } } } ) } \geq 0.5 .
Our results imply that massive SMGs are experiencing centrally enhanced star formation unlike typical spiral galaxies in the local Universe .
The sizes and stellar densities of our SMGs are in agreement with those of the passive population at z = 1.5 , consistent with these systems being the descendants of z \simeq 2 SMGs .