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 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

Today

Age of the U

niverse

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 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

Visible (baryonic) Matter is at theCenter 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 Infrared Submm/mm

Add Add DustDust

Infrared/submm Spectrum of Galaxies: Dust & Gas

Dust: Graphite,Silicates…..

Gas: Atomic (H, C, O, N….)

Molecular (CO, HCO+…)

M83Optical 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 (1012 Lsun) matches energy output of UV-selected population at high z

0.7<Z<2.5 Z=2.55

Cluster A1835

Dust and CO in BR1202-0725 at z=4.7

1.2 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 10-20

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 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)