Milky Way Analogues in MaNGA: Multi-Parameter Homogeneity and Comparison
  to the Milky Way
  The Milky Way provides an ideal laboratory to test our understanding of
galaxy evolution, owing to our ability to observe our Galaxy over fine scales.
However, connecting the Galaxy to the wider galaxy population remains
difficult, due to the challenges posed by our internal perspective and to the
different observational techniques employed. Here, we present a sample of
galaxies identified as Milky Way Analogs (MWAs) on the basis of their stellar
masses and bulge-to-total ratios, observed as part of the Mapping Nearby
Galaxies at Apache Point Observatory (MaNGA) survey. We analyse the galaxies in
terms of their stellar kinematics and populations as well as their ionised gas
contents. We find our sample to contain generally young stellar populations in
their outskirts. However, we find a wide range of stellar ages in their central
regions, and we detect central AGN-like or composite-like activity in roughly
half of the sample galaxies, with the other half consisting of galaxies with
central star-forming emission or emission consistent with old stars. We measure
gradients in gas metallicity and stellar metallicity that are generally flatter
in physical units than those measured for the Milky Way; however, we find far
better agreement with the Milky Way when scaling gradients by galaxies' disc
scale lengths. From this, we argue much of the discrepancy in metallicity
gradients to be due to the relative compactness of the Milky Way, with
differences in observing perspective also likely to be a factor.
