MaNGA

Mapping Nearby Galaxies at APO (MaNGA)

MaNGA obtains spectra across the entire face of target galaxies using custom designed fiber bundles. The bottom right illustrates how the array of fibers spatially samples a particular galaxy. The top right compares spectra observed by two fibers at different locations in the galaxy, showing how the spectrum of the central regions differs dramatically from outer regions. Image Credit: Dana Berry / SkyWorks Digital Inc., David Law, and the SDSS collaboration.
MaNGA obtains spectra across the entire face of target galaxies using custom designed fiber bundles. The bottom right illustrates how the array of fibers spatially samples a particular galaxy. The top right compares spectra observed by two fibers at different locations in the galaxy, showing how the spectrum of the central regions differs dramatically from outer regions. Image Credit: Dana Berry / SkyWorks Digital Inc., David Law, and the SDSS collaboration.

Unlike previous SDSS surveys which obtained spectra only at the centers of target galaxies, MaNGA enables spectral measurements across the face of each of ~10,000 nearby galaxies thanks to 17 simultaneous “integral field units” (IFUs), each composed of tightly-packed arrays of optical fibers. MaNGA’s goal is to understand the “life history” 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 two-dimensional 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 size, inclination, 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 billion years. An overview of the project is presented in Bundy et al. 2015. Additional technical publications are listed here.

The image below shows an example of a galaxy observed with MaNGA, together with maps of derived galaxy properties.

MaNGA Technical Details

  • Dark-time observations
  • Fall 2014 – Spring 2020
  • 17 IFUs per 7 deg2 plate
  • Wavelength: 360-1000 nm, resolution R~2000
  • 10,000 galaxies across ~2700 deg2, redshift z~0.03
  • roughly 3-hour dithered exposures
  • Spatial sampling of 1-2 kpc
  • Per-fiber S/N=4-8 (per angstrom) at 1.5 Re
The SDSS image of a galaxy observed by MaNGA; the pink hexagon shows the size of the MaNGA IFU
The SDSS image of a galaxy observed by MaNGA; the pink hexagon shows the size of the MaNGA IFU
 Example of a galaxy observed with MaNGA, showing from left to right: stellar velocity field, Hα emission line map, galactic gas velocity field.

Credit: Francesco Belfiore, Univ. of St Andrews Print & Design.
Example of a galaxy observed with MaNGA, showing from left to right: stellar velocity field, Hα emission line map, galactic gas velocity field.

Credit: Francesco Belfiore, Univ. of St Andrews Print & Design.

Sample Selection

Galaxies are selected from the NASA Sloan Atlas catalog of the SDSS Main Galaxy Legacy Area, with selection cuts applied only to redshift, i-band luminosity, and for a subset of galaxies, NUV-r color. The Field Layout Forecast page provides information on where MaNGA has already observed and the on-sky locations most likely to be observed over the course of the survey.

  • Roughly flat stellar mass distribution with M > 109 M
  • Smallest galaxy diameter sampled by 25 spatial bins
  • Primary sample: 67%, radial coverage to 1.5 Re (effective or half-light radius)
  • Secondary sample: 33%, radial coverage to 2.5 Re
  • No size or inclination cuts
A MaNGA target galaxy, 500 Myr away
A MaNGA target galaxy, 500 Myr away
On the left, an image of the face of a 127 fiber IFU. Its ferrule housing which holds the IFU and allows it to be plugged into the SDSS plate is shown on the right.
On the left, an image of the face of a 127 fiber IFU. Its ferrule housing which holds the IFU and allows it to be plugged into the SDSS plate is shown on the right.

Instrumentation

  • Buffered fibers with 120 micron (2″) core diameters
  • Close-packed hexagonal fibers IFUs, 54% live-core fill factor
  • IFU size from 19 to 127 fibers, diameters from 12″ to 32″
  • IFU complement per plate: 2×19; 4×37; 4×61; 2×91; 5×127
  • 92 IFU-associated sky fibers
  • 12 7-fiber “mini-bundles” for spectrophotometric calibration
  • Total number of fibers: 1423

People

Principal Investigator
Kevin Bundy (Kavli IPMU)
Survey Scientist:
Renbin Yan (Kentucky)
Lead Data Scientist
David Law (STScI)
SDSS-IV Project Scientist:
Matthew Bershady (Wisconsin)
Science Team Chair
Daniel Thomas (Portsmouth)
Deputy Science Team Chair
Cheng Li (Tsinghua)
Instrument Scientist
Niv Drory (UT Austin)
Chief Engineer/Project Manager:
Nick MacDonald (Washington)
Sample Design Lead
David Wake (Open University)
Lead Observer
Anne-Marie Weijmans (St Andrews)
EPO Liaison
Mariana Cano Díaz(UNAM)
Early Career Scientists Representative
Francesco Belfiore (Cambridge)
Follow us on twitter: @MaNGASurvey