« The stellar systems are scattered through space as far as telescopes can penetrate. We find them smaller and fainter, in constantly increasing numbers, and we knowthat we are reaching out into space, until, with the faintest nebulae than can be detected with greatest telescopes, we arrive at the frontiers of the knownUniverse. »
Edwin Hubble, The Realm of the Nebulae (1936)
Spiral Galaxy NGC1512
A Galaxy is a large Assemblage of Stars, Gas and Dust that is held together by the mutual gravitational interaction between its Constituents. Galaxies contain between a few million and about ten trillion Stars together with differing proportions of interstellar matter (Gas & Dust)
A Galaxy:the Tip of the Iceberg of Dark Matter
Angular Momentum of the Halo Dark Matter Halo
Old Stars
Young Stars
SupernovaCold Gas
Hot Gas
100 kpc
M=1012 Msol
The Early Universe
The last scattering surface of the cosmic microwave background reveals information on very low amplitude density variations in the dark matter 300,000 years after the Big Bang, and on the origin of these fluctuations within the first 10-35 sec.
COBE
Boomerang
Simulations of the Developments of Large Scale Structures in the Universe: Dark Matter and Gas Dynamics
Foreground Cluster Abell 2218
Background Galaxies
The Distribution of (invisible) Dark Matter can be mapped using the (Gravitational Lens) Distortion of the Images of Background Galaxies
Galaxies at z> 2 are multiplewith evidence of merging
Assembly of large Galaxies wasevidently completed at z<1
Galaxy Evolution
Infrared/submm Spectrum of Galaxies: Dust & Gas
Dust: Graphite,Silicates…..
Gas: Atomic (H, C, O, N….)
Molecular (CO, HCO+…)
Optical is not the whole story
Population of rare but high luminosity sources (1012 Lsun) matches energy output of UV-selected population at high z
A next Generation mm/submm Telescope
ALMA•a mm/submm equivalent of VLT, HST, NGST with corresponding high
sensitivity and angular resolution but unhindered by dust opacity
•a capability to see star-forming galaxies out to the highest redshifts
Surveys of high redshift galaxies with ALMA
mm/submm sensitive searches to obscured, star-forming regions
TODAY: about 200 sources known
ALMA: many 100,000 sources
ALMA will detect objects to redshifts as high as 10-20
Into the Reionization Epoch
Morphology, Physical & Chemical Properties
ALMA will revolutionize our understanding of the Formation
of Galaxies in the early Universe
•mm/submm is a vital new window on the distant Universe
–unobscured view of star-forming galaxies, at wavelengths containing most of the luminosity of the distant Universe
•ALMA’s sensitivity and angular resolution are essential to realize this potential
•ALMA’s scientific contributions will include studies of the earliest galaxies, an accounting of the bolometric luminosity of the distant Universe, and the evolution of galaxies, quasars and the elements over cosmic time
« We are, by definition, in the very center of the observable region. We know our immediate neighborhood rather intimately. With increasing distance, our knowledge fades, and fades rapidly. Eventually, we reach the dim boundary, the utmost limits of ourTelescopes. There, we measure shadows, and we search amongghostly errors of measurement for landmarks that are scarcelymore substantial.
The search will continue. Not until the empirical resources areexhausted, need we pass on the dreamy realms of speculation. »
Edwin Hubble, The Realm of Nebulae (1936)