Mapping Nearby Galaxies at APO

An image of a spiral galaxy with the face of a MaNGA 127 fiber integral field unit (IFU) superimpossed. Galaxies are being selected from the SDSS Main Galaxy Legacy Area, with selection cuts applied to only redshift and a color-based stellar mass estimate.

Unlike previous SDSS surveys which measured spectra only at the centers of target galaxies, MaNGA's tightly-packed optical fiber arrays will enable spectral measurements across the face of each of ~10,000 nearby galaxies. MaNGA’s goal is to understand the “life cycle” of present day galaxies from imprinted clues of their birth and assembly, through their ongoing growth via star formation and merging, to their death from quenching at late times.

To answer these questions, MaNGA will provide 2-D maps of stellar velocity and velocity dispersion, mean stellar age and star formation history, stellar metallicity, element abundance ratio, stellar mass surface density, ionized gas velocity, ionized gas metallicity, star formation rate, and dust extinction for a statistically powerful sample. The galaxies are selected to span a stellar mass interval of nearly 3 orders of magnitude. No cuts are made on color, morphology or environment, so the sample is fully representative of the local galaxy population. Just as tree-ring dating yields information about climate on Earth hundreds of years into the past, MaNGA’s observations of the dynamical structures and composition of galaxies will help unravel their evolutionary histories over several billions of years.


The new SDSS will measure spectra at multiple points in the same galaxy using a newly-created fiber bundle. The bottom right illustrates how each fiber will observe a different section of the galaxy. The top right shows data gathered by two fibers observing two different parts of the galaxy, demonstrating how the spectrum of the central regions differs dramatically from outer regions.
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