Constrain the stellar population gradient of elliptical galaxies with SED

We use multiple wavelength photometric data, from Optical to NIR, to determine the radial gradient of stellar populations of nearby elliptical galaxies. Empirical model, such as the Sersic profile, is assumed to describe the radial stellar distribution, and the metallicity gradient is parameterlized in this model. The PSF effects of different wavebands are also involved to predict the photometric profiles which can be compared with observational surface brightness profile directly. For most of elliptical galaxies, they have negative gradients, which means their central parts is metal rich than outer parts. We also found the gradient is significantly correlated to the stellar mass of the whole galaxy. More massive elliptical galaxies have shallower gradients. But for our sample galaxies, their is no correlations between Sersic n and mass, and between Sersic n and gradient can be found.