Transcript R. Bender (ESO)

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.
• 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).
Achievements and 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 groundbased 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
galaxies.
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):
• 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-energy observatories
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.