Galaxy Formation Now and Then Matthias Steinmetz Astrophysikalisches Institut Potsdam 1
Overview The state of galaxy formation now The state of galaxy formation 10 years ago Extragalactic astronomy in 10 years Problems we may ponder Conclusions 2
Galaxy formation now Cosmological parameters fixed (sort of) Hierarchical clustering is the paradigm of structure formation in the Universe Modeling galaxy formation populations: semi-analytical models details: N-body + hydro simulations Galaxy morphology reflects merging history Hubble-sequence in place at z 1 Thousands of UV-dropout galaxies at z 3: 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 Hierarchical clustering: theorist s favored model, but highly disputed among observers Modeling galaxy formation non-evolution vs passive evolution individual galaxies w/o cosmological context Galaxy morphology reflects merging history??? Galaxies at z=1??? Some high-z objects (QSOs, radio galaxies) Tens of models for Ly-alpha clouds 4
z=9.00 32.5/h Mpc 50 million particle N-body simulation 5
z=4.00 32.5/h Mpc 50 million particle N-body simulation 6
z=2.33 32.5/h Mpc 50 million particle N-body simulation 7
z=1.00 32.5/h Mpc 50 million particle N-body simulation 8
z=0.00 32.5/h Mpc 50 million particle N-body simulation 9
Morphology reflects merging history redshift 20 kpc X-Y color: age X-Z color: age 10
Morphology reflects merging history 11
Morphology reflects merging history composite disk stars halo stars gas 12
Morphology reflects merging history thick disk thin disk 13
Ly-alpha forest = cosmic web 14
Success and failure of the model + 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 at z=0-0.5: Hubble sequence, scaling laws Absorption systems associated with galaxies Few QSOs, low UV background Where are most of the baryons? at z=1: fairly similar story (?) at z=3: 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 MAP, Planck: cosmological parameters fixed GAIA: formation history of the Milky Way Routine usage of 2 nd generation instruments on ground-based 8m telescopes NGST: very high-z universe Moore s law: computers a factor 100 faster Performance of computers will not be a problem (G)astrophysics will be the problem 17
Some problems to ponder High resolution analysis of the nearby galaxy population 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 Kinematics, scaling laws Find and confirm higher magnitude UV dropouts building blocks of the present galaxy pop. observe the establishment of the Hubble sequence 18
Some problems to ponder Create a 3D map of the baryons in the Universe from z=3 to z=0 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 F UV (z) detailed reionization history Imaging + spectroscopy: locations of galaxies in that cosmic web 19