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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. Gemini Integral Field Spectroscopy.
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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
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 (5+5 nights GMOS+CIRPASS) • 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
GEMINI-NORTH GMOS-IFU 10-15 June 2002 4-9 August 2002 GEMINI-SOUTH
Exquisitely sensitive to line emission redshifted between OH • Star formation at z>1 (Ha, [OIII]5007Å, Hb, [OII]3727Å) • 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 IFU Science
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 R~4000 • 100km/s resolution effective at working between sky lines, but (near) read-noise limit Targets - emission lines from: • z=1 lensed arc (kinematics) • z=1.2 3C radio galaxy (alignment effect etc.) • z=3 damped system & QSO (extended Lyman-a)
A z=1.2 radio galaxy 3C324 • Extended blue light over >5", aligned with radio • 3C radio galaxy z=1.2 deep HST im. • studied by Spinrad & Dickinson • evidence of a cluster • size well-suited to GMOS/CIRPASS • study emission lines [OII] & H-alpha (kinematics)
GMOS IFU Spectroscopy Gemini-N • 3C324 z=1.21 radio galaxy - raw data [OII]3727Å @z=1.2 8000Å 8300Å Andrew Bunker (IoA, Cambridge) Euro3D Meeting July 2002
GMOS IFU Spectroscopy Gemini-N • 3C324 z=1.21 radio galaxy - "reduced" 2D (still has sky & cosmics, but extracted fibres) 8300Å 8000Å [OII]3727Å @z=1.2 Andrew Bunker (IoA, Cambridge) Euro3D Meeting July 2002
[OII]3727 structure has two velocity components at +/-400km/s 3C324 3-D data cube Wavelength/velocity
z=1.03 Pello et al. (1992) • Good lens model for this cluster Abell2218 • Reconstruct galaxy image • GMOS to study [OII]3727Å emission line • Spatially-resolved kinematics • Infer mass given lensing stretch • Tully-Fisher @z=1? z=1.03 lensed arc
z=1 arc 3D data cube [OII]3727Å doublet, ~300km/s velocity shift Wavelength/velocity
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 (Dl=2200Å) at R~4000: great sensitivity between OH sky lines • Limiting line flux on Gemini ~2x10-18 ergs/sec/cm^2 (5s, 3 hours) What is CIRPASS? 500 fibres IFU Instrument cryostat On dome floor
Damped Ly-a QSO Absorption Systems Bunker, Warren et al.
CIRPASS, GMOS and Gemini • Does CIRPASS have the sensitivity & throughput? • YES - at z~1 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 z>1 • 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)