The MaNGA Dwarf Galaxy Sample (MaNDala): stellar profiles and gradients characterization

We derived radial profiles and inner/outer gradients of various stellar population (SP) properties for 124 bright dwarf galaxies, ${10}^{7.53}\le M_{\ast }\mathrm{/}{M}_{\odot }\le {10}^{9.06}$, from the MaNDala sample, using integral field spectroscopy observations. Given the complex structure of dwarf galaxies, we used four different methods to derive SP radial profiles: two based on concentric elliptical rings, and two exploiting the spatially resolved data. For each method, we applied four approaches to calculate the inner ($0\le R\mathrm{/}{R}_e\le 1$) and outer ($0.75\le R\mathrm{/}{R}_e\le 1.5$) gradients of: luminosity- and mass-weighted age and stellar metallicity, dust attenuation, $D_{n4000}$ index, stellar mass and star formation rate (SFR) surface densities, and specific SFR. While the PSF has a minor impact on the SP gradients, the methodology for characterizing radial profiles significantly affects them. At fixed property, differences in inner gradients from concentric rings methods are $\sim 0.05\text{-}0.1\text{ dex/}{R}_e$, while outer gradients can reach $0.5\text{-}1\text{ dex/}{R}_e$, relative to the median of all gradients of that property, $\text{med}(\{\mathrm{\nabla }\mathcal{G}{\}}_i)$. Spatially resolved methods yield smaller differences, $\lesssim 0.1\text{ dex/}{R}_e$. For some SP gradients, e.g. ${\mathrm{\nabla }}_{\text{SFR}}$, the dispersion among the methods is comparable to $\text{med}(\{\mathrm{\nabla }\mathcal{G}{\}}_i)$. While it is not possible to select a single preferred method for determining SP gradients, we suggest to use $\text{med}(\{\mathrm{\nabla }\mathcal{G}{\}}_i)$ for each SP property. The resulting median age and metallicity suggest that, overall, bright dwarfs experienced moderate inside-out formation, and significant early SF from low-metallicity gas with outward radial migration of old SPs. The derived SP gradients provide strong constraints on feedback mechanisms in dwarf galaxies.