The Milky Way-like radial structure in nearby galaxies

Abstract

The Milky Way exhibits a distinctive plateau in its inner surface brightness profile around one effective radius, challenging the traditional view of a purely exponential disk. To explore the origin of this feature, we identify 65 nearby galaxies ($<50$ Mpc) with similar plateau structures and analyze their multi-band surface brightness and color profiles using SDSS, DESI, 2MASS, and Mephisto data. Of the 65 galaxies with Milky Way-like plateaus, 42 have bar classifications (25 barred, 17 non-barred). Barred galaxies show radial color variations more consistent with stellar population ageing, while non-barred galaxies align more with the dust reddening direction, suggesting dust attenuation contributes to plateau formation in non-barred systems. The broad range of color gradients among barred galaxies suggests bars influence plateaus through multiple pathways, including stellar population variations and dynamical stellar-mass redistribution. Environment may also contribute: both barred and non-barred galaxies tend to reside in denser environments than a comparison sample without plateaus. The low occurrence rate ($\sim$3.6\%) may indicate that plateau structures mark a relatively uncommon evolutionary stage. The Milky Way, with both strong stellar population dependence and a persistent stellar mass profile feature, may represent an intermediate case where both stellar population variations and dynamical processes associated with the bar shape its plateau.