Integral Field Spectroscopy on Gemini

Andrew Bunker (IoA, Cambridge) Euro3D Meeting July 2002

GMOSGemini Multi-Object Spectrograph, optical

IFU (Durham)

Gemini Integral Field Spectroscopy

· 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

· 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)

GMOS-IFU

GEMINI-SOUTH

GEMINI-NORTH

10-15 June 2002

4-9 August 2002

IFU Science 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 1M/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

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

Andrew Bunker (IoA, Cambridge) Euro3D Meeting July 2002

8000Å 8300Å

[OII]3727Å @z=1.2

GMOS IFU Spectroscopy Gemini-N· 3C324 z=1.21 radio galaxy - "reduced" 2D

(still has sky & cosmics, but extracted fibres)

Andrew Bunker (IoA, Cambridge) Euro3D Meeting July 2002

8000Å 8300Å

[OII]3727Å @z=1.2

3C324 3-D data cube

[OII]3727 structure has two velocity components at +/-400km/s

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z=1.03 lensed arc · 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 arc 3D data cube

[OII]3727Å doublet, ~300km/s velocity shift

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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

(Dl=2200Å) at R~4000: great sensitivity between OH sky lines

· Limiting line flux on Gemini ~2x10-18 ergs/sec/cm^2 (5 , s 3 hours)

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)