Integral Field Spectroscopy on Gemini

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Integral Field Spectroscopy on Gemini
GMOS
Gemini Multi-Object Spectrograph, optical IFU
(Durham)
Andrew Bunker (IoA, Cambridge) Euro3D Meeting
July 2002
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Gemini Integral Field Spectroscopy

• Institute of Astronomy, Cambridge Andy Bunker,
  Joanna Smith (PhD student), Richard McMahon,
  Gerry Gilmore Ian Parry, Rob Sharp etc (CIRPASS
  team)
• Durham Richard Bower, Roger Davies etc GMOS
  team
• Gemini Kathy Roth, Marianne Takamiya, Inger
  Jørgensen etc. (Director's discretionary time)

• Program with Gemini Observatory to demonstrate
  the power of IFUs (55 nights GMOSCIRPASS)
• Large interntational team (CIRPASS observations
  involve 50 scientists) lead by Cambridge/Durham
• Aimed at raising profile of IFU science in the
  Gemini community
• Data made public in 2 months

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GEMINI-NORTH
GMOS-IFU
10-15 June 2002
4-9 August 2002
GEMINI-SOUTH
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IFU Science

• Exquisitely sensitive to line emission redshifted
  between OH
• Star formation at z1 (Ha, OIII5007Å, Hb,
  OII3727Å)
• Robust star formation rate measures down to
  1MM/yr
• Rotation curves, kinematics
• Masses, extinction, metallicity
• Nature of damped Lyman-a systems at high-z
• Lensed galaxies/dark matter sub-clumping
• Dynamics of dense Galactic stellar systems
• Ages of young star clusters

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GMOS Optical IFU Spectroscopy

• Gemini-N 10-15 June 2002 Andrew Bunker, Joanna
  Smith (IoA, Cambridge), Richard Bower (Durham)
  supported by Inger Jørgensen (Gemini)
• 3 good nights out of 5 0.6" FWHM seeing, 0.2"
  fibres
• Used wide-field' 2-slit mode - 5"x7", use
  broad-band filters as order sorters
• Used moderately high spectral resolution R4000
• 100km/s resolution effective at working between
  sky lines, but (near) read-noise limit
• Targets - emission lines from
• z1 lensed arc (kinematics)
• z1.2 3C radio galaxy (alignment effect etc.)
• z3 damped system QSO (extended Lyman-a)

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A z1.2 radio galaxy 3C324

• Extended blue light over 5", aligned with radio
• 3C radio galaxy z1.2 deep HST im.
• studied by Spinrad Dickinson
• evidence of a cluster
• size well-suited to GMOS/CIRPASS
• study emission lines OII H-alpha (kinematics)

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GMOS IFU Spectroscopy Gemini-N

• 3C324 z1.21 radio galaxy - raw data

OII3727Å _at_z1.2
8000Å
8300Å
Andrew Bunker (IoA, Cambridge) Euro3D Meeting
July 2002
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GMOS IFU Spectroscopy Gemini-N

• 3C324 z1.21 radio galaxy - "reduced" 2D (still
  has sky cosmics, but extracted fibres)

8300Å
8000Å
OII3727Å _at_z1.2
Andrew Bunker (IoA, Cambridge) Euro3D Meeting
July 2002
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3C324 3-D data cube
OII3727 structure has two velocity components
at /-400km/s
Wavelength/velocity
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z1.03 lensed arc

• z1.03 Pello et al. (1992)
• Good lens model for this cluster Abell2218
• Reconstruct galaxy image
• GMOS to study OII3727Å emission line
• Spatially-resolved kinematics
• Infer mass given lensing stretch
• Tully-Fisher _at_z1?

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z1 arc 3D data cube
OII3727Å doublet, 300km/s velocity shift
Wavelength/velocity
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What is CIRPASS?

• Near-infrared integral field unit
• Built with UK government (PPARC) private money
  by IoA Cambridge
• Wavelengths 0.9-1.8mm (z, J, H) doubles range of
  Gemini IFU science
• Working since June 2001 (passed Gemini benchmark
  test July 2001)
• Fibre fed - sits on dome floor
• 490 spatial samples variable image scales
  0.05"-0.33" up to 5"x12" field
• Large wavelength coverage (Dl2200Å) at R4000
  great sensitivity between OH sky lines
• Limiting line flux on Gemini 2x10-18
  ergs/sec/cm2 (5s, 3 hours)

500 fibres IFU
Instrument cryostat
On dome floor
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Damped Ly-a QSO Absorption Systems
Bunker, Warren et al.
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CIRPASS, GMOS and Gemini

• Does CIRPASS have the sensitivity throughput?
• YES - at z1 can reach sub-Milky Way star
  formation rates predicted by hierarchical
  formation
• Is the IFU more efficient than long slit?
• YES -for our spatially-extended targets
• Can this science be done with GMOS IFU alone?
• NO -requires IR for Ha/OIII/Hb z1
• BUT coupling optical near-IR integral field
  spectroscopy can act as a "science multiplier
• We have used GMOS/IFU in June to hit many of the
  CIRPASS targets (metallicity extinction)