The Dark Energy Survey and The Dark Energy Spectrograph Josh Frieman DES Project Director .
GMT’s Near IR Multiple Object Spectrograph - NIRMOS
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Transcript of GMT’s Near IR Multiple Object Spectrograph - NIRMOS
GMT’s Near IR Multiple Object Spectrograph - NIRMOS
Daniel FabricantCenter for Astrophysics
NIRMOS Scientific Drivers
• Discovery and characterization of the first galaxies
• Assembly and evolution of galaxies at z=2 to 3
• Chemical evolution of galaxies
GMT and NIRMOS probe galaxy evolution from first light
Tentative IR detection of Ly α emission looking back 13 Gyr (Stark et al. 2007) ~10 hrs with Keck.
“At the faint limits now being probed, we have found the reliable identification and verification of distant Ly α emitters to be a very challenging endeavor, even with the most powerful facilities available to us.”
Galaxies in formation 11 Gyr ago
Galaxies are different at z=2
Kriek et al. 2009
Compact red sequence galaxy 11 Gyr ago
Van Dokkum, Kriek & Franx 2009
This galaxy has a stellar mass of3 x 1011 Mּס despite its tiny size!
Evolution of massive galaxies
van Dokkum et al. 2010
Re = 3 kpc10 Gyr ago
Re = 8 kpc6 Gyr ago
Galaxies selected from mass-number density relation at constant number density
29 hr spectrum of H=20 Galaxy with Gemini 8 m
GMT will attain S/N of 10 for H=22.5 in 10,000 sec in natural seeing
Van Dokkum, Kriek & Franx 2009Kriek et al. 2009
JWST and GMT: natural partners
James Webb Space Telescope
2014
Giant Magellan Telescope
2018
JWST NIRCam imaging
2 arcminutes
10 square arcminutes in two bands
0.07″ images at 2.2 µm
Superb photometry and galaxy stucture
JWST’s NIRSpec
At R=100 with very low background, JWST is a superb tool for rapid redshift measurements and selection of galaxy samples
At the resolution needed for dynamical mass measurements, a GMT instrument can provide greater sensitivity and larger fields of view than NIRSpec
• Multiple object spectrographat R=100 and R=1000 with 9 square arcminute FOV
• IFU and long slit at R=3000
•0.2″ nominal slit width
GMT IR spectroscopy of distant galaxies
• Go faint: Observe galaxies 11 Gyr ago with ~3 x 1010 Mּס HVega=22.5 or HAB=24
• Infrared: Distant quiescent galaxies are bright at λ > 1.4 µm
• Wide-field: ~3 galaxies arcmin-2 at z > 2
• Spectral resolution: λ/Δλ~3000 for 100 km s-1 resolution and to reduce OH contamination
• Angular resolution: 3 kpc ~0.36 arcsec (LCO median at H), GLAO assist helpful
GMT’s NIRMOS
NIRMOS Field of View35 square arcminutes
~105 z>2 galaxies!
• 0.9 to 2.5 μm imaging spectrograph
• Natural seeing or GLAO
• R~3000 with 0.5″ slit and full J, H, or K coverage – higher resolution possible
• Superb image quality: worst 80% EE better than 0.15″
•Volume Phase Holographic gratings reduce scattering (and OH background) by order of magnitude
NNNIRSpec
GMT/NIRMOS at R=3000 is twice as sensitive as JWST/NIRSpec at R=1000, with 4x the field of view
Ground Layer Adaptive Optics
GLAO will improve spatial resolution by ~2
1.5 kpc resolution at z=2.5, same as JWST NIRSpec
Ground layer wavefront errors are weakly dependent on field angle
NIRMOS optical layoutFused Quartz
CaF2 (foursegments)
CaF2CaF2
aspheric
S-TIM28
Fused Quartz
• 275 mm collimated beam diameter
•CaF2 lens blanks < 390 mm diameter available from current production
• Volume Phase Holographic gratings for dispersers
4 meters
Critical technologies for NIRMOSTechnology Status
Large calcium fluoride lens blanks Canon/Optron quote in hand
Large S-TIM28 lens blanks Ohara quote in hand
Detector array Teledyne will produce, estimate in hand
Large cryogenic VPH gratings - Kaiser Optical could produce, K band performance the major open item
Ground layer adaptive optics $ Dependent on adaptive secondary mirror – soft fallback to seeing limited operation
NIRMOS at GMT’s Gregorian Focus
NIRMOS mechanical layout
Optics and mechanics cooled to 120 K
Collimator optics
Camera Optics
Filter and gratingwheels
Slit mask cassette
ImagingSpectroscopy
5m
NIRMOS focal plane area
Manifest fibers
Tip/tilt guiders
Slit mask cassette
Cryocoolers
Conclusions
• We believe that NIRMOS has great scientific potential, is technically feasible and affordable
• We invite our GMT partners to explore NIRMOS science with us
• We look forward to exploiting the potential of IR fiber technology with the MANIFEST team
• We are interested in collaborations in IR technology with GMT partners
The End
High Altitude Turbulence Restricts the Diffraction-limited Field of View
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NIRMOS in the JWST era
• NIRMOS at R=3000 is 2x as sensitive than NIRSpec at R=1000, with 4x the field of view
• NIRMOS at R=3000 is ~10x more sensitive than NIRSpec at R=3000 and retains MOS
• In natural seeing, NIRMOS attains S/N of 10 in 10,000 s at H=22.5 (0.5 x 0.5 arcsec)
NIRMOS at GMT’s Gregorian focus
NIRMOS mechanical layout
Optics and mechanics cooled to < 100 K