Expected progress and break-throughs in ground-based extragalactic astronomy Ralf Bender

1. Expected progress and break-throughs in ground-based extragalactic astronomy Ralf Bender ESO Council FORS Deep Field

2. Achievementsand Challenges2003: • Cosmological framework in which galaxies evolve is now • sufficiently well determined. • WMAP and Planck are determining the cosmological • parameters with increasing accuracy. • The main cosmological problems of the future are the • nature of dark matter and dark energy. Attacking these in • the astrophysical context requires both detailed studies of • galaxies and clusters ( central dark matter density profiles) • and large O/NIR/submm surveys ( nature of dark energy • from SNIa, clusters; dark matter distribution from lensing).

3. Achievementsand Challenges 2003 (continued): • Evolution of cold dark matter ‘easy’ to model and seems • understood at scales larger than galaxy size. • Evolution of baryonic component complex and not at all • well understood (difficult interplay between star formation, • nuclear activity, different gas phases, collaps and merging). • Stellar ages of galaxies in conflict with hierarchical formation? • (massive galaxies are old, low mass galaxies young) • Formation of supermassive black holes in galaxy centers • in relation to galaxy formation/evolution still in the dark…

4. New capabilities on the ground and synergies with space observatories

5. Imaging capabilites in optical/NIR will reach hundreds • of megapixels (VST/OmegaCAM: 2004, VISTA: 2007) • Multicolor optical-IR surveys enable reliable photometric redshifts and classifications for tens of millions of galaxies. The evolution of type-dependent galaxy luminosity functions can be derived, cosmic variance can be analyzed, and targets for follow-up (e.g. spectroscopy) with large ground- based telescopes and satellites can be selected. • The dark matter distribution can be analyzed with the weak gravitational shear effect. Variable objects (AGN, SNIa) can be searched efficiently. • Combination with surveys in X-rays, radio, submm, HST… • opens new research opportunities ( Virtual Observatory)

6. The spectroscopic survey capabilities for galaxy • studies are increasing rapidly (FORS, ISAAC: 1998, • VIMOS: 2003, FLAMES: 2003, KMOS, MUSE: 2009) • Evolution of large scale structure / galaxy clustering can • be analyzed to high redshifts. • Intrinsic kinematics, stellar population properties, gas content and star formation activity of galaxies can be measured to highest z allowing to follow the mass assembly and morphology evolution over time. •  Complementary observations by Hubble Space Telescope • are crucial for detailed structural analysis (radii, densities, • disk-to-bulge ratios …): GOODS, GEMS, COSMOS…

7. Adaptive optics and laser beacons will increase the • spatial resolution by a factor of ~3 over HST over • tens of arcseconds (NACO, SINFONI: 2003, 2005) • Detailed structural and kinematical studies of merging and star-forming galaxies up to high redshift. • Analysis of physical conditions in Active Galactic Nuclei. • Search for inactive supermassive black holes in nearby galaxies. • Structure of star formation regions in nearby galaxies (most of these fields up to now served by HST)

8. VLT Interferometry of relatively faint sources will • become possible through PRIMA and can provide • spatial resolutions in the milliarcsec range: ~2007 • In the Galactic center, the black hole parameters can be determined more accurately. General relativistic effects can be measured (precession of pericenter of stellar orbits) • Interferometry is the only way to study the dust tori around the central engines of Active Galactic Nuclei (the dust tori are expected to have a crucial influence on the nature of an AGN).

9. ALMA will open a new window to sensitive, high • resolution mm and sub-mm observations: >2007 • ALMA can analyse the mm and submm continuum and thousands of molecular lines to characterize dust and gas in the universe (wavelength and spatial resolution complementary to Herschel). • ALMA will provide a view complementary to O/IR into the assembly of galaxies and dust-enshrouded violent star formation processes that may have produced a large fraction of all stars in the universe, especially those in spheroids. • ALMA will allow to probe the collapse of the first massive galaxy fragments before they have largely turned into stars. • ALMA can detect molecular absorption lines in many quasars, the Sunyaev-Zeldovich ( Planck) effect to high redshift, ...

10. An ELT/OWL will lead into a new era of ground-based • extragalactic astronomy because of its superb • resolution and extreme light collecting power: >2012 • High redshift universe can be studied in the same detail as the local universe today (e.g. SDSS at z~3 is possible). • High resolution spectra of intergalactic medium allow detailed analysis of chemical enrichment history. • Earliest phases of star and galaxy formation at z>7 (complementary to ALMA in wavelength and to JWST in resolution and light collecting power) • Systematic studies of large numbers of SNIa to constrain nature of dark energy. • Analysis of local galaxies as we analyse the Galaxy today (stellar populations, assembly history)

11. World-class facilities for extragalactic astronomy beyond 2010 (ground,space): • 8-10m class O/IR telescopes • With adaptive optics & second generation instruments • Linked interferometrically (VLTI) • Supported by survey telescopes (VST, VISTA) • ALMA, Herschel for mm/submm regime • HST: UV, O, NIR; followed by JWST: O, NIR, MIR • Extremely Large Telescopes (OWL?) • LOFAR, and eventually SKA, for radio regime • GAIA: spectroscopy and kinematics of the Milky Way • High-energyobservatories

12. What extragalactic astronomy may be missing in UV/O/NIR capabilities: • Wide-field high spatial resolution UV/O satellite (SNAP?). • The survey satellite for the low surface brightness universe: SB ~ (1+z)-4 , i.e. the central surface brightness of the Galaxy’s disk at z ~ 3 is about 28 KAB/arcsec2!! i.e., JWST can do it, but a satellite like PRIME or WISE is more efficient.