NIFS Science Case and Performance

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NIFS Science Case and Performance

• What is NIFS?
• What makes a successful AO instrument?
• What will limit NIFS performance?
• What science will NIFS do?

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Near -infrared Integral Field Spectrograph (NIFS)
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Near -infrared Integral Field Spectrograph (NIFS)

• Near-infrared, integral-field spectrograph.
• Used with ALTAIR AO system on Gemini North.
• Performs near diffraction-limited imaging
  spectroscopy.
• Field-of-view 3.0??3.0? in 29 IFU slitlets.
• Spatial pixel size 0.10??0.04?.
• Wavelength range 0.94-2.5 ?m.
• Gratings Z, J, H, K.
• Spectral resolving power 5300 (two pixels).
• Detector Rockwell 2048?2048 HAWAII-2
  HgCdTe/PACE.
• Near-infrared OIWFS.

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Compressed image of K 15 mag star, Strehl
0.2, seeing FWHM 0.4?
y
?
x

• 3.0??3.0? FOV
• 0.1? wide slitlets
• 0.04??0.1? spatial pixels
• 2048 spectral pixels

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Simulated K15 mag star, 1800 s, K grating
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What makes a successful AO instrument?

• Guide star availability.
• Guide stars, guide stars, guide stars

• Surface brightness sensitivity.
• Small pixels high resolution no photons!

• Competitive science.
• Limited suite of instruments.
• Nearest object at higher resolution, not distant
  objects.
• Parts of NIR spectrum are unavailable.
• OH airglow emission.

• Broad user base.
• Convenient preparation and operation.

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NIFS Guide Star Availability
NGS

• AOWFS r lt 20?, R lt 15 mag.
• OIWFS r lt 60?, R lt 16 mag.

• Low flexure gt no OIWFS star?

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Galaxies to 20 Mpc
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Seyfert Galaxies ( 50 Mpc)
45 of 99 Seyfert galaxies tested probably have
suitable OIWFS stars.
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Ultra-Luminous IR Galaxies
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NIFS Guide Star Summary

• Guide star availability is a challenge.

• Natural Guide Star system
• 4 of extragalactic targets have random AOWFS
  stars.
• Some can use the object as AOWFS star (e.g.,
  Seyferts).
• 35 of extragalactic targets have random OIWFS
  stars.

• Laser Guide Star system
• 9 of extragalactic targets have random OIWFS
  stars.

• Observations of prototype objects will be
  difficult.

• Best to choose objects based on proximity to
  bright stars.

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Implications for MCAO

• How many key objects have 3 OIWFS stars?
• How will users efficiently identify faint stars?

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NIFS Performance Model (NIFSSIM)

• Realistic noise sources.
• Detector dark current, read noise.
• Cryostat, telescope, ALTAIR thermal emission.
• Sky continuum and line emission.
• Scattered light.
• Realistic throughput.
• AR-coated mirrors and lenses.
• Approximate grating efficiencies.
• Simulated source signals.
• Realistic data reduction.
• Sky-subtraction.

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Dominant Noise Sources in 3600 s

• Long integrations required to overcome read
  noise.
• Dark current pattern must be removed.
• Background-limited at K due to ALTAIR.
• K lt 18.0 mag is source noise limited (27 hr for
  1).

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Point Source Performance Summary
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Extended Continuum Source Summary

• K13.5 mag/arcsec2 is the central surface
  brightness of a
• nearby bright galaxy in 1? seeing.

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Extended Line Source Summary
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Implications for MCAO

• Need high surface brightness in a spatial or
  spectral sense.
• Stars, or
• Line emission.
• MCAO should be substantially cryogenic!
• NIFS prediction is 1 mag worse than claimed for
  MCAO!

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NIFS Science Drivers

• Massive black holes. R 3000-5000
• AGN in nearby galaxies. R 3000
• Low mass stars. R 1000
• Compact star clusters. R 2000
• YSO jet mechanisms. R 3000-6000
• YSO/cloud interactions. R 6000
• Proto/planetary nebulae. R 6000
• Galactic center. R 3000-4000
• Stellar populations in nearby galaxies. R
  1000-3000
• Starburst galaxies. R 3000-5000
• ULIR galaxies. R 3000-5000
• High redshift galaxies? R 4000-6000
• Lyman break galaxies? R 4000-6000
• QSO host galaxies? R 1000-3000

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Galactic Center
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Redshifted Optical Emission-Lines
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Disk Galaxies at z 1
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Which Galaxies to Study?

• At z 1
• FH? 3.5 ? 10-23 W cm-2
• M(B) -20.5 mag

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Disk galaxy, H? in J grating, z 1.0, 3600 s
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H36555_1249 z 0.950 proto-spiral?