P-MaNGA: full spectral fitting and stellar population maps from prototype observations

Abstract

MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a 6-year\nSDSS-IV survey that will obtain resolved spectroscopy from 3600 $\\AA$ to 10300\n$\\AA$ for a representative sample of over 10,000 nearby galaxies. In this\npaper, we derive spatially resolved stellar population properties and radial\ngradients by performing full spectral fitting of observed galaxy spectra from\nP-MaNGA, a prototype of the MaNGA instrument. These data include spectra for\neighteen galaxies, covering a large range of morphological type. We derive age,\nmetallicity, dust and stellar mass maps, and their radial gradients, using high\nspectral-resolution stellar population models, and assess the impact of varying\nthe stellar library input to the models. We introduce a method to determine\ndust extinction which is able to give smooth stellar mass maps even in cases of\nhigh and spatially non-uniform dust attenuation.\n With the spectral fitting we produce detailed maps of stellar population\nproperties which allow us to identify galactic features among this diverse\nsample such as spiral structure, smooth radial profiles with little azimuthal\nstructure in spheroidal galaxies, and spatially distinct galaxy sub-components.\nIn agreement with the literature, we find the gradients for galaxies identified\nas early-type to be on average flat in age, and negative (- 0.15 dex / R$_e$ )\nin metallicity, whereas the gradients for late-type galaxies are on average\nnegative in age (- 0.39 dex / R$_e$ ) and flat in metallicity. We demonstrate\nhow different levels of data quality change the precision with which radial\ngradients can be measured. We show how this analysis, extended to the large\nnumbers of MaNGA galaxies, will have the potential to shed light on galaxy\nstructure and evolution.\n