1 The Scientific Context for NGAO Mark Morris, representing the NGAO Scientific Advisory Team (NSAT): Tommaso Treu, Laird Close, Michael Liu, & Keith Matthews

What is the NSAT? A group of active members of the Keck users community, representing the UC system, Caltech, U Hawaii, & the NASA community. Convened in 2009 by the WMKO directors (originally 8 members) CHARGES: –provide science advice to the NGAO project, with an emphasis on further development of the science cases and science requirements –help to ensure that the NGAO facility will provide the maximum possible science return for the investment and that NGAO will meet the scientific needs of the Keck community –determine optimal observing and operations strategies –provide advice on design trades, science priorities –support funding efforts by contributing to proposals –elicit broad community input and support for the project Meetings ~1/month by teleconference, with participation by the observatory directors and the NGAO team 2

3 Context for NGAO – growing demand for LGS-AO on large telescopes ➜ the clear advantage of sky coverage. Peer-reviewed publications: Note the dominance of Keck, but other observatories are knocking hard on the door… 3

4 Adaptive optics usage at WMKO has increased dramatically over the past decade, and is still rising … 4

5 All major research communities are employing LGS AO … 55 Total LGS Solar Sys Galactic Extra- galactic 2010 to date: 6 months

6 Key Science Cases – Requirements Drivers 1. High-redshift galaxies, internal structure and dynamics at z = 1 – 3 2. Black hole masses in nearby AGNs: resolving the Keplerian velocity increase within the black holes’ sphere of influence 3. General Relativity at the Galactic center: precision stellar orbits to discover and measure post-Newtonian effects. 4. Planetary companions to low-mass stars & brown dwarfs: taking advantage of the favorable contrast, & using a coronagraph 5. Asteroid and KBO companions : size, shape, composition & orbits of companions to minor planets with the aim of reconstructing their history 6 These push limits of AO system, instrument, and telescope. Determine the most demanding performance requirements.

7 Simulation of radial velocities observed along the major axis of an emission-line disk surrounding a black hole in a galaxy center.

Observational Attributes:  near-diffraction limited performance in the near-IR (K Strehl ~80%). On Keck, this provides the highest spatial resolution available at any of its operating wavelengths. Very high Strehl  key enabler of the science envisioned with NGAO.  substantially increased sky coverage, compared to existing AO systems  AO corrections at wavelengths as short as 7000 Å  imaging with a reconstructable and only moderately variable PSF over the entire science field (~20”)  photometry, astrometry, deconvolution  integral field spectroscopy at R~4000 from 0.7 to 2.4 µm, with three pixel scales: 10, 35, and 50 (or 70) mas, with 5.6” x 3” FOV at 50 mas sampling. - AO-fed medium-resolution NIR IFS unique among AO systems under development. 88

9 Calcium triplet 850 nm How is NGAO different from Keck’s AO today? NGAO: same Strehl at Ca Triplet as LGS today in H band NGAO: better Strehl at J band than LGS today in K band NGAO: much higher sky coverage NGAO: same Strehl at Ca Triplet as LGS today in H band NGAO: better Strehl at J band than LGS today in K band NGAO: much higher sky coverage

10 NGAO changes the AO observing experience Routinely exquisite correction Rarely ‘marginal’ performance Monte Carlo performance estimate simulating 44 nights observing (Galaxy Assembly science case), drawing random values for r 0, wind speed, sodium abundance, and zenith angle (KAON 716, Figure 12) Includes comparison with M. Liu’s measured K2 LGS data ( = 17%), the KAON 721 predict for K2 LGS ( = 20%), and NGAO predict ( = 70%)

11 -=- Sky coverage -=- Many science cases, particularly extragalactic ones such as Galaxy Assembly and Star Formation History are strongly affected by NGAO’s sky coverage Need to look at random places in the sky Out of the plane of the Galaxy In select “Deep Fields” that were chosen by others to have very few stars Need to accumulate a good statistical sample of galaxies in order to draw conclusions

12 MOAO correction of IR tip-tilt stars has large benefit for sky coverage Example: Keck NGAO, galaxy assembly science case, zenith angle 30 deg, median seeing at Mauna Kea Current Keck TT Current Keck EE 50 NGAO TT NGAO EE 50

13 NGAO: dramatic improvements in SNR for IFU spectra of distant galaxies Cooled AO system to reduce thermal background (K-band) Increased instrument throughput (34% vs. 19%) Higher spatial resolution means better point source sensitivity 13 Antennae Galaxies Local H  image LGS AO z =2.5 NGAO z = 2.5 SNR in H 

14 Advantages of NGAO for Resolved Stellar Populations 1.Reduced confusion from halos of adjacent stars: means better photometry on more stars 2.Color magnitude diagrams give better discrimination using I – K colors than using J – K or H – K colors (next slides) 3.Improved astrometry lets you better determine cluster membership (next slides) Olsen Blum and Rigaut 2003 GSMT simulation of NGC 1835

15 Resolved Stellar Populations Visible-light AO = better discrimination between stellar populations due to longer lever-arm of I-K vs. J-K for color-magnitude diagrams. 15

16 Resolved Stellar Populations High Strehl ratios reduce confusion = more stars, better astrometry 16 KKH 98 NGC 6297 (Anderson et al. 2008)

Four Major Wide Field AO Systems are under Development Tradeoffs: spatial resolution, strehl, PSF uniformity 17

NGAO Will Be the Leader in High Performance Narrow Field AO 18 contrast, Strehl, sky coverage NGAO more robust

A broad array of other investigations is enabled by NGAO, some of which have been used as additional science drivers  Gravitationally lensed galaxies  QSO host galaxies  Circumnuclear disks in galaxies  Extended gaseous structures at high redshifts  Resolved stellar populations in extragalactic systems  The internal dynamics of star clusters, young and old  Debris disks  Young stellar objects, protostellar disks, & jets  Stellar winds: bubbles, bow shocks, & pinwheels  Planetary & preplanetary nebulae – launching of bipolar flows  Jovian planet atmospheres: climate and wind dynamics  Planetary rings, satellites, and their interactions 19

11 So far, 40 astronomers have helped develop the NGAO Science Cases Ádámkovics, Mate Ammons, Mark Auger, Matt Barth, Aaron Bouchez, Antonin Cameron, Brian *Close, Laird de Pater, Imke Eisner, Joshua Emery, Joshua Fassnacht, Chris Ghez, Andrea Greene, Tom Hammel, Heidi Hillenbrand, Lynne Jonsson, Patrik Koo, David Larkin, James Law, David Liu, Michael Lu, Jessica Macintosh, Bruce Marchis, Franck Marshall, Phil *Matthews, Keith Max, Claire McGrath, Liz Melbourne, Jason Melling, Laura Metchev, Stanimir *Morris, Mark *Nierenberg, Anna Noll, Keith Novak, Greg Olsen, Knut Steidel, Chuck Suyu, Sherry *Treu, Tommaso Vegetti, Simona Weinberg, Nevin * Current NSAT Members New science cases from other scientists are always welcome

21 Competitive Landscape: JWST JWST advantages –JWST will have better sensitivity than NGAO (low backgrounds) at K band, but lower at J –Diffraction limited imaging between 2.4 and 5  m –Multiplexed slit spectroscopy (x 100) –Spectral resolution R = 2700 Keck NGAO advantages –Better spatial resolution than JWST at wavelengths below 2  m  JWST pixels under-sample the diffraction limit at wavelengths shorter than 2  m –Spectroscopy at spatial resolutions < 0.1” –Spectroscopy at spectral resolutions R > 2700

22 NGAO complementarity to TMT Technology groundbreaking for NFIRAOS In TMT era, Keck NGAO can play key role in screening targets for follow-up with scarce TMT time TMT advantages –Higher spatial resolution –Higher sensitivity –Wide field with partial correction (IRMS) Keck NGAO advantages –Higher sky coverage (LGS AO corrected tip-tilt stars) –Half-decade head start –Synoptic studies –More CIT & UC community access for NGAO For AGN black hole mass measurements, NGAO using Ca II triplet is comparable with TMT in K band (CO bandhead).

23 Summary  NGAO’s very high Strehl over a substantial field of view, coupled with a dramatic improvement in sky coverage, would bring considerable scientific return, and enable both major progress in existing investigations as well as new kinds of scientific investigations.  All areas of astronomy would profit from this capability; the number of significant science cases so far indicates that the demand for this capability will be enduring, even into the era of JWST and TMT.