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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)
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