Visit and talk by Thomas Greve – University of Copenhagen

18 May 2009

Visit and talk by Thomas Greve

Thomas greve is visiting Dark Cosmology Centre from Monday 18 May - Wednesday 20 May. He is currently a postdoc at MPIA, Germany.

Thomas Greve will give a talk entitled "ALMA - pathfinder to the origin of galaxies and supermassive black holes" Tuesday 19 May, at 14:15 in the DARK lounge .


How and when did the first galaxies form? What is the origin of the supermassive
black holes (SMBHs) found in the centers of nearly every galaxy today? These are the questions that will define the next decade of extragalactic astronomy. The Atacama Large Millimeter Array (ALMA) - located in the Atacama desert in Chile and scheduled to begin early science operations at the end of 2010 will be the prime facility withwhich to tackle these questions in the years to come.

The formation of the first galaxies and SMBHs took place during a benchmark period in Cosmic history called the Epoch of Reionization (EoR) in which the emerging radiation fields from stars and SMBHs gradually ionized the surrounding gas. This period is thought to have lasted from a few hundred million years to about 1Gyr after the Big Bang.

These first objects were deeply imbedded in gas and dust, making them invisible to even the most powerful optical/near-IR telescopes. ALMA, however, will be able to penetrate the dust and measure the physical properties of the gas in galaxy and black hole environments. ALMA will produce spatially and kinematically resolved images of the gas and dust in proto-galaxies -  a unique capability setting it apart from future facilities such as the James Webb Space Telescope (first light 2015+) - thereby directly discriminating between galaxy formation scenarios from little more than a simple visual inspection of the gas/dust morphologies.

Secondly, ALMA will determine whether the primordial molecular gas from which the first structures formed was excited by X-rays (accretion onto black holes) or by UV-photons (star formation), making ALMA a unique instrument with which to determine the abundance of SMBHs at z > 6, and thus their origin.