Science Nugget—A Detailed Science Case for TMT
  David Silva (AURA/TMT), Paul Hickson (UBC), C. Steidel (CIT), Michael Bolte (UCO/Lick)

Those of us alive today are extraordinarily lucky to have the answers to some of the deepest questions about the universe around us. We have arrived at a moment when we can see the imprint of the Big Bang everywhere we look: from the smallest ripples in the cosmic microwave background to the filaments of galaxies stretching across the sky of the present day universe to the very water in our bodies.

But our journey of exploration is not over, not all has been revealed.

So begins the TMT Detailed Science Case: 2007 (DSC) for the TMT, developed by our Science Advisory Committee, a group of scientist-advocates who represent the future TMT scientific user community. This document is now available from our public Web site.

The DSC begins with an overview readily accessible to interested non-specialists. The overview is followed by topical discussions that include example observational programs. These examples are not exhaustive in scope but serve to illustrate where TMT will provide breakthrough capabilities and/or illustrate especially demanding technical requirements. We do not pretend that these observations will lead to the only exciting results – our experience tells us that those results will come during explorations we cannot imagine today. But our experience tells us also that what we can imagine today can be used to make sure we will build the right vehicle for the explorations of tomorrow.

The main sections of the DSC are:

Fundamental physics and cosmology – TMT observations can constrain the nature of dark matter, dark energy, and other aspects of what is often called the Standard Model. Many of these observations involve precise measurements of stellar dynamics in our own Galactic Center (see Figure 2) as well as in nearby, dark matter dominated dwarf galaxies. Predicted extensions to the Standard Model can be tested by measuring whether or not certain fundamental constants have changed with time.

The early Universe – in coordination with the James Webb Space Telescope, TMT will investigate the first stars and galaxies in the Universe. In particular, TMT will have the light gathering power and resolution needed to study the physical nature of first-light objects initially detected by JWST. TMT will also observe the effects of first-light objects on surrounding gas and learn how and when the intergalactic medium became ionized.

Galaxy formation and evolution – by studying objects forming only two billion years after the Big Bang, TMT will provide a new window on physics of galaxy formation and the interaction of that process with the surrounding gas. Individual objects will be studied in unprecedented detail using a technique known as integral field spectroscopy. High resolution, three-dimensional tomographic maps of the Universe will be built using spectra of hundreds of distant background galaxies (see Figure 3). These maps will be similar in nature to CAT scan maps of the human brain.

Extragalactic supermassive black holes – by measuring stellar and gas velocities in the centers of galaxies in both the nearby and distance Universe, TMT will provide constraints on the nature of black holes that contain the mass of millions of Suns and how these supermassive black holes have evolved in concert with their parent galaxies across cosmic time.

Exploration of nearby stars – one can think of nearby stars as the fossil record of the early Universe – but unlike paleontology, we can make direct connections between this fossil record and the events that produced it. The large collecting area and high spatial resolution of TMT (even better than the Hubble and James Webb Space Telescopes) will allow heretofore impossible detailed studies of individual stars in galaxies outside of the Milky Way (see Figure 4). These studies will provide insights into the physical conditions during star formation in the early Universe as well as how galaxies were assembled and evolved in the more local Universe.

The formation of stars and planets – the details of how stars and planets form are still largely uncertain. Working with both JWST and ALMA, TMT will peer into the stellar and planetary nurseries throughout the local Universe to study these formation events as they happen.

Exoplanets – the hunt is on for Earth-like planets circling nearby stars and TMT will be able to detect such planets orbiting within the habitable zones of M stars, the most common stars in the galaxy. It is also possible that TMT will be the first facility to detect signatures of biological life in exo-planet atmospheres.

Our Solar System – the outer planets in our solar system are visited by unmanned spacecraft perhaps once per decade, but TMT can study them in complementary detail almost any time.