Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
April 4th,
2002
Galaxy Formation
Now and Then
Matthias Steinmetz
Astrophysikalisches
Institut Potsdam
1
Overview
April 4th,
2002
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
n The
state of galaxy formation now
n The state of galaxy formation 10 years ago
n Extragalactic astronomy in 10 years
n Problems we may ponder
n Conclusions
2
Galaxy formation now
Cosmological parameters fixed (sort of)
n Hierarchical clustering is the paradigm of structure
formation in the Universe
n Modeling galaxy formation
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
n
u
u
Galaxy morphology reflects merging history
n Hubble-sequence in place at z ≈1
n Thousands of UV-dropout galaxies at z ≈3:
n
u
April 4th,
2002
populations: semi-analytical models
details: N-body + hydro simulations
u
n
progenitors of cluster ellipticals
bursting dwarfs at high redshift
}⇒
not the building blocks
of present day L* gals
Ly-alpha forest: absorption due to the cosmic web
3
Galaxy formation ten years ago
Cosmological parameters poorly constrained
n Hierarchical clustering: theorist’s favored model,
but highly disputed among observers
n Modeling galaxy formation
April 4th,
2002
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
n
u
u
non-evolution vs passive evolution
individual galaxies w/o cosmological context
Galaxy morphology reflects merging history ???
n Galaxies at z=1 ???
n Some high-z objects (QSOs, radio galaxies)
n Tens of models for Ly-alpha clouds
n
4
April 4th,
2002
32.5/h Mpc
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
z=9.00
50 million
particle
N-body
simulation
5
April 4th,
2002
32.5/h Mpc
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
z=4.00
50 million
particle
N-body
simulation
6
April 4th,
2002
32.5/h Mpc
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
z=2.33
50 million
particle
N-body
simulation
7
April 4th,
2002
32.5/h Mpc
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
z=1.00
50 million
particle
N-body
simulation
8
April 4th,
2002
32.5/h Mpc
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
z=0.00
50 million
particle
N-body
simulation
9
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
Morphology reflects merging history
redshift
April 4th,
2002
20 kpc
X-Y
color: age
X-Z
color: age
10
April 4th,
2002
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
Morphology reflects merging history
11
April 4th,
2002
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
Morphology reflects merging history
composite
disk stars
halo stars
gas
12
April 4th,
2002
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
Morphology reflects merging history
thick disk
thin disk
13
April 4th,
2002
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
Ly-alpha forest = cosmic web
14
Success and failure of the model
April 4th,
2002
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
+
+
+
−
−
−
main components of galaxies (disk, bulge,
bar, halo)
Tully-Fisher, fundamental plane
Lyman-alpha forest
angular momentum of disk galaxies
formation of pure disk galaxies
dark matter in disk galaxies (cusps vs
cores)
15
High-z universe vs low-z universe
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
n
at z=0-0.5:
u
u
u
u
?
at z=1: fairly similar story (?)
n at z=3:
n
u
u
u
u
April 4th,
2002
Hubble sequence, scaling laws
Absorption systems associated with galaxies
Few QSOs, low UV background
Where are most of the baryons ?
n
Galaxies lumpy and interacting, scaling laws ????
Absorption systems often not associated with galaxies (?)
QSOs, high UV background
Most baryons in the Ly-alpha forest
Do we test the same or at least related populations ?
16
Extragalactic astronomy in 10 yrs
April 4th,
2002
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
n MAP,
Planck: cosmological parameters fixed
n GAIA: formation history of the Milky Way
n Routine usage of 2nd generation instruments
on ground-based 8m telescopes
n NGST: very high-z universe
n Moore’s law: computers a factor 100 faster
Performance of computers will not be a problem
u (G)astrophysics will be the problem
u
17
Some problems to ponder
April 4th,
2002
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
n
High resolution analysis of the nearby galaxy
population
u
u
n
Stellar populations
Detailed 2D kinematics
Deep high resolution imaging and spectroscopy of
UV dropout galaxies and of gal’s at z=1-2.5
Morphology
u Kinematics, scaling laws
u Find and confirm higher magnitude UV dropouts
⇒ building blocks of the present galaxy pop.
⇒ observe the establishment of the Hubble sequence
u
18
Some problems to ponder
April 4th,
2002
Hubble's Science Legacy: Future Optical -UV
Astronomy From Space
n
Create a 3D map of the baryons in the Universe
from z=3 to z=0
u
u
u
u
u
Fainter QSO (maybe bright UV dropouts ?) as
background sources
Many LOS for several patches
Absorption spectra unravel temperatures, densities,
ionization states, LOS velocities, metallicities of the
IGM/cosmic web as a function of redshift
Transverse proximity effect ⇒ FUV(z) ⇒ detailed
reionization history
Imaging + spectroscopy: locations of galaxies in that
cosmic web
19