1. Extragalactic AO Science James Larkin AOWG Strategic Planning Meeting September 19, 2004

2. Fundamental motivations Galaxies quickly shrink below 1” in size making ground-based observations difficult, but their sub-structures like bulges remain above the Keck diffraction limit to arbitrary redshift. Galaxies quickly shrink below 1” in size making ground-based observations difficult, but their sub-structures like bulges remain above the Keck diffraction limit to arbitrary redshift. 5 kpc 2 kpc 0.5 kpc Good Optical/NIR Seeing Keck Diffraction Limit @ 1.6  m  M =0.25,   =0.75, H o =70 km/s/Mpc 1” Sb Galaxy @ z=0.5

3. Fundamental motivations At high redshift, optical spectral lines shift into the infrared where AO correction is best and HST has had limited impact. At high redshift, optical spectral lines shift into the infrared where AO correction is best and HST has had limited impact. Magic redshift ~ 2.3 Magic redshift ~ 2.3 H  & NII in K band H  & NII in K band OIII & H  in H band OIII & H  in H band OII, 4000 Break in J band OII, 4000 Break in J band This is probably the formation epoch of MW-like disks (1” diameter). This is probably the formation epoch of MW-like disks (1” diameter). Most gravitational lenses occur in areas under a couple of arcseconds, and weakly lensed galaxies are elongated by of order an arcsecond. Most gravitational lenses occur in areas under a couple of arcseconds, and weakly lensed galaxies are elongated by of order an arcsecond. Even for extended sources, AO on Keck provides increased sensitivity. Especially powerful in identifying point-like sources within galaxy. Even for extended sources, AO on Keck provides increased sensitivity. Especially powerful in identifying point-like sources within galaxy. Crowding of stars in nearby systems prevents accurate analysis of stellar populations. Crowding of stars in nearby systems prevents accurate analysis of stellar populations. The internal structure of most nearby active nuclei is unresolved with one arcsecond resolution. The internal structure of most nearby active nuclei is unresolved with one arcsecond resolution.

4. Fundamental Problems Guide star brightness Guide star brightness Very few galaxies have sufficiently bright cores for high-order AO systems. Very few galaxies have sufficiently bright cores for high-order AO systems. Only ~10 -4 of objects are near bright foreground stars Only ~10 -4 of objects are near bright foreground stars Curvature systems are currently doing most of the extragalactic science, but with limited Strehl. Curvature systems are currently doing most of the extragalactic science, but with limited Strehl. Surface Brightness Surface Brightness Sensitivity increases rapidly with Strehl for point sources, but extended targets gain much less. Sensitivity increases rapidly with Strehl for point sources, but extended targets gain much less. AO systems produce additional background in Near-IR and reduce throughput further making it difficult to observe faint extended sources. AO systems produce additional background in Near-IR and reduce throughput further making it difficult to observe faint extended sources. Normal galaxy disks only achieve a maximum SB of K~16 mag/sq arcsec and this fades as (1+z) 4. This means all normal disks are fainter than 22.5 mag within 0.05x0.05”. Normal galaxy disks only achieve a maximum SB of K~16 mag/sq arcsec and this fades as (1+z) 4. This means all normal disks are fainter than 22.5 mag within 0.05x0.05”. Galaxy evolution improves this affect. Galaxy evolution improves this affect. Observations take hours even for imaging. Observations take hours even for imaging.

5. What will the laser do… Provide consistent performance on variety of sources. Provide consistent performance on variety of sources. Allow for target selection by characteristics. Allow for target selection by characteristics. Open up HST deep fields and ground based redshift fields. Open up HST deep fields and ground based redshift fields. Brightest star within ultra deep field is R~15 mag Brightest star within ultra deep field is R~15 mag Opens up the study of rare but important objects such as Lyman-break galaxies, sub-mm galaxies, and ultraluminous infrared galaxies. Opens up the study of rare but important objects such as Lyman-break galaxies, sub-mm galaxies, and ultraluminous infrared galaxies. Allow studies of stellar populations as a controlled function of radius. Allow studies of stellar populations as a controlled function of radius. Improves Strehl since extragalactic sources have depended on off-axis guide stars. Improves Strehl since extragalactic sources have depended on off-axis guide stars. Generally beneficial to all areas of extragalactic science. Generally beneficial to all areas of extragalactic science.

6. What would higher order do for you without a laser Reduce fraction of sky available, probably becoming totally dependent on foreground off-axis stars. Reduce fraction of sky available, probably becoming totally dependent on foreground off-axis stars. Increased sensitivity to point sources, and better contrast. Increased sensitivity to point sources, and better contrast. Probably only beneficial to a few areas of stellar population studies if still dependent on natural guide stars. Probably only beneficial to a few areas of stellar population studies if still dependent on natural guide stars.

7. Other areas that will benefit extragalactic science… Cleaner (or better coatings) and colder AO systems, and better throughput. Cleaner (or better coatings) and colder AO systems, and better throughput. K–band is probably the most important filter K–band is probably the most important filter Local thermal background can devastate faint object work. Local thermal background can devastate faint object work. Integral field spectroscopy Integral field spectroscopy Avoids slit losses. Avoids slit losses. Samples complex geometry. Samples complex geometry. Multiplex advantage on resolved stellar populations. Multiplex advantage on resolved stellar populations. SINFONI is commissioned on VLT. SINFONI is commissioned on VLT. 9 out of 12 approved science verification programs are extragalactic 9 out of 12 approved science verification programs are extragalactic

8. Some big questions future AO could address Assembly of galaxy masses. Complex kinematics at z~1, Lyman break kinematics at z~3. Modern mass disks at z~2? Assembly of galaxy masses. Complex kinematics at z~1, Lyman break kinematics at z~3. Modern mass disks at z~2? Variations within NLR of individual AGN, and detailed comparisons of many AGN. Testing standard paradigm. Variations within NLR of individual AGN, and detailed comparisons of many AGN. Testing standard paradigm. Evolutionary (or not) linkages between ULIRGS, Quasars and normal galaxies. Evolutionary (or not) linkages between ULIRGS, Quasars and normal galaxies. Cosmological constant – High redshift type-Ia supernovae. Cosmological constant – High redshift type-Ia supernovae. Formation of bulges and tie to central black hole. Formation of bulges and tie to central black hole. Central velocity dispersions in local galaxies. Central velocity dispersions in local galaxies. Bulge formation tied to quasar epoch? Bulge formation tied to quasar epoch? Test new CDM models of galaxy formation. Test new CDM models of galaxy formation.

9. Technology with biggest impact Laser, especially with faint TT magnitudes Laser, especially with faint TT magnitudes PSF Characterization (stability,telemetry)– accurate photometry and morphology PSF Characterization (stability,telemetry)– accurate photometry and morphology General improvements: better wavefront sensor CCD, faster reconstructor, cleaner optics. General improvements: better wavefront sensor CCD, faster reconstructor, cleaner optics.