ALMA and the Formation of Galaxies Pierre Cox IAS, Orsay, France

« 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 know that 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 known Universe. » 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 Supernova Cold Gas Hot Gas 100 kpc M=10 12 M sol

  Today  Age of the Universe Redshift Hierarchical Formation

HOW WERE THE GALAXIES FORMED ? 300,000 yr after the Big Bang 12 billion yr later

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 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 multiple with evidence of merging Assembly of large Galaxies was evidently completed at z<1 Galaxy Evolution

Visible (baryonic) Matter is at the Center of the Gravitational Wells

The merging of two Galaxies

Stephan’s Quintet

The Center of the Milky Way Optical Submillimeter (SCUBA) The Effect of Dust

UV Visible InfraredSubmm/mm Add Dust

Infrared/submm Spectrum of Galaxies: Dust & Gas Dust: Graphite, Silicates….. Gas: Atomic (H, C, O, N….) Molecular (CO, HCO+…)

M83 Optical Carbon Monoxide CO(1-0) SEST

The Antennae Galaxy HST Optical image HST Optical image + CO

Optical is not the whole story Population of rare but high luminosity sources (10 12 L sun ) matches energy output of UV- selected population at high z

0.7<Z<2.5 Z=2.55 Cluster A1835

Dust and CO in BR at z= mm Continuum MAMBO CO emission PdB & Nobeyama

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 Into the Reionization Epoch Morphology, Physical & Chemical Properties

High Angular Resolution & Sensitivity SCUBA resolution ALMA resolution

Gravitational Lensing by a Cluster of Galaxies Submillimeter Optical

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 our Telescopes. There, we measure shadows, and we search among ghostly errors of measurement for landmarks that are scarcely more substantial. The search will continue. Not until the empirical resources are exhausted, need we pass on the dreamy realms of speculation. » Edwin Hubble, The Realm of Nebulae (1936)