MaNGA

A MaNGA target galaxy, 500 Myr away

Mapping Nearby Galaxies at APO (MaNGA): Unlike previous SDSS surveys which measured spectra only at the centers of target galaxies, MaNGA  bundles sets of optical fibers into tightly-packed arrays, enabling 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.

Key Science Questions

  • How does gas accretion drive the growth of galaxies?
  • What are the roles of stellar accretion, major mergers, and instabilities in forming galactic bulges and ellipticals?
  • What quenches star formation? What external forces affect star formation in groups and clusters?
  • How was angular momentum distributed among baryonic and non-baryonic components as the galaxy formed?
  • How do various mass components assemble and influence one another?

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 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 image below shows some example data and derived maps from a galaxy observed in a test run of the MaNGA instrument which happened in January 2013. We’ll soon have examples from our recent commissioning run of March 2014.

Example MaNGA maps from the Jan 2013 test run. Credit: Sebastian Sanchez.

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 ~4000 deg2, redshift z~0.03
  • 3-hour exposures with dithering
  • Spatial sampling of 1-2 kpc
  • Per-fiber S/N=5-10 at 1.5 Re

Sample Selection

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.

  • Flat stellar mass distribution with M > 109 Msun
  • Smallest galaxy diameter sampled by at least 5 spatial bins
  • Primary sample: 67%, spatial coverage to 1.5 Re (effective or half-light radius)
  • Secondary sample: 33%, spatial coverage to 2.5 Re
  • No size or inclination cuts

Instrumentation

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.
  • 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)
  • Chief Engineer and Project Manager: Nick MacDonald (Washington)
  • Survey Scientist: Renbin Yan (Kentucky)
  • Instrument Scientist: Niv Drory (UT Austin)
  • Lead Data Scientist: David Law (Dunlap Institute, Toronto)
  • Sample Design Lead: David Wake (Open University, Wisconsin)
  • Lead Observer: Anne-Marie Weijmans (St Andrews)
  • Science Team Chair: Daniel Thomas (Portsmouth)
  • Composition Strategic Committee: Alfonso Aragon-Salamanca (Nottingham), Roberto Maiolino (Cambridge), Cheng Li (SHAO), Christy Tremonti (Wisconsin)
  • Kinematics Strategic Committee: Karen Masters (Portsmouth), Remco van den Bosch (MPIA), Mike Merrifield (Nottingham), Eric Emsellem (ESO)

Follow us on twitter: @MaNGASurvey


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