Prof. Dan Maoz of TAU's Raymond and Beverly Sackler School of Physics and Astronomy is spearheading a project that has just discovered twelve of the most distant and ancient supernovas ever seen, ten of them in a part of the sky called the Subaru Deep Field. He and his colleagues say that their discovery will enhance their knowledge of the "dark energy" that is causing the universe to expand, as well as the origins of life on our own planet.
© NASA, The Hubble Heritage Team and A. Riess (STScI) Intricate spiral arms contain areas of new star formation in this dusty galaxy. This galaxy, which lies about 100 million light-years away, toward the direction of the constellation Leo, was home to a supernova that appeared in 1994.
Out of the 150 supernovas observed, 12 were among the most distant and ancient ever seen.
The discovery sharpens our understanding of the nature of supernovas and their role in element formation, say study leaders Prof. Dan Maoz, Dr. Dovi Poznanski and Or Graur of TAU's Department of Astrophysics at the Raymond and Beverly Sackler School of Physics and Astronomy. These "thermonuclear" supernovas in particular are a major source of iron in the universe.
The research, which appears in the Monthly Notices of the Royal Astronomical Society this month, was done in collaboration with teams from a number of Japanese and American institutions, including the University of Tokyo, Kyoto University, the University of California Berkeley, and Lawrence Berkeley National Laboratory.
A key element of the universe
Supernovas are nature's "element factories." During these explosions, elements are both formed and flung into interstellar space, where they serve as raw materials for new generations of stars and planets. Closer to home, says Prof. Maoz, "these elements are the atoms that form the ground we stand on, our bodies, and the iron in the blood that flows through our veins." By tracking the frequency and types of supernova explosions back through cosmic time, astronomers can reconstruct the universe's history of element creation.
In order to observe the 150,000 galaxies of the Subaru Deep Field, the team used the Japanese Subaru Telescope in Hawaii, on the 14,000-foot summit of the extinct Mauna Kea volcano. The telescope's light-collecting power, sharp images, and wide field of view allowed the researchers to overcome the challenge of viewing such distant supernovas.
By "staring" with the telescope at the Subaru Deep Field, the faint light of the most distant galaxies and supernovas accumulated over several nights at a time, forming a long and deep exposure of the field. Over the course of observations, the team "caught" the supernovas in the act of exploding, identifying 150 supernovas in all.
Sourcing man's life-blood
According to the team's analysis, thermonuclear type supernovas, also called Type-la, were exploding about five times more frequently 10 billion years ago than they are today. These supernovas are a major source of iron in the universe, the main component of the Earth's core and an essential ingredient of the blood in our bodies.
Scientists have long been aware of the "universal expansion," the fact that galaxies are receding from one another. Observations using Type-Ia supernovas as beacons have shown that the expansion is accelerating, apparently under the influence of a mysterious "dark energy" - the 2011 Nobel Prize in Physics will be awarded to three astronomers for this work. However, the nature of the supernovas themselves is poorly understood. This study improves our understanding by revealing the range of the ages of the stars that explode as Type-la supernovas. Eventually, this will enhance their usefulness for studying dark energy and the universal expansion, the researchers explain.
They say their discovery will enhance their knowledge of the "dark energy". They should look no further than the people of their state who have absorbed this dark energy.