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GMT’s Near IR Multiple Object Spectrograph - NIRMOS. Daniel Fabricant Center 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.
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GMT’s Near IR Multiple Object Spectrograph - NIRMOS Daniel Fabricant Center 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 are different at z=2 Kriek et al. 2009
Compact red sequence galaxy 11 Gyr ago This galaxy has a stellar mass of 3 x 1011 Mסּ despite its tiny size! Van Dokkum, Kriek & Franx 2009
Evolution of massive galaxies Re = 8 kpc 6 Gyr ago Re = 3 kpc 10 Gyr ago Galaxies selected from mass-number density relation at constant number density van Dokkum et al. 2010
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 2009 Kriek et al. 2009
JWST and GMT: natural partners James Webb Space Telescope 2014 Giant Magellan Telescope 2018
JWST NIRCam imaging 10 square arcminutes in two bands 0.07″ images at 2.2 µm Superb photometry and galaxy stucture 2 arcminutes
JWST’s NIRSpec • Multiple object spectrograph • at R=100 and R=1000 with 9 square arcminute FOV • IFU and long slit at R=3000 • 0.2″ nominal slit width At R=100 with very low background, JWST is a superb tool for rapid redshiftmeasurements 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
GMT IR spectroscopy of distant galaxies • Go faint: Observe galaxies 11 Gyr ago with ~3 x 1010 Mסּ 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 NN • 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 NIRSpec NIRMOS Field of View 35 square arcminutes ~105 z>2 galaxies! 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 Ground layer wavefront errors are weakly dependent on field angle GLAO will improve spatial resolution by ~2 1.5 kpc resolution at z=2.5, same as JWST NIRSpec
NIRMOS optical layout Fused Quartz CaF2 CaF2 S-TIM28 CaF2 (four segments) Fused Quartz aspheric 4 meters • 275 mm collimated beam diameter • CaF2 lens blanks < 390 mm diameter available from current production • Volume Phase Holographic gratings for dispersers
NIRMOS mechanical layout Spectroscopy Imaging Slit mask cassette Collimator optics 5m Filter and grating wheels Camera Optics Optics and mechanics cooled to 120 K
NIRMOS focal plane area Cryocoolers Slit mask cassette Manifest fibers Tip/tilt guiders
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
High Altitude Turbulence Restricts the Diffraction-limited Field of View *
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 mechanical layout Optics and mechanics cooled to < 100 K