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

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Expected progress and break-throughs in ground-based extragalactic astronomy Ralf Bender ESO Council FORS Deep Field. Achievements and Challenges 2003: Cosmological framework in which galaxies evolve is now sufficiently well determined.

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Expected progress and break-throughs in

ground-based extragalactic astronomy

Ralf Bender

ESO Council

FORS Deep Field

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).
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…
New capabilities on the ground and

synergies with space observatories

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)
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…
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


  • Structure of star formation regions in nearby galaxies

(most of these fields up to now served by HST)

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).

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, ...

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)

world class facilities for extragalactic astronomy beyond 2010 ground space
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
what extragalactic astronomy may be missing in uv o nir capabilities
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.