FINDING THE MISSING LINK: NASA PHYSICS AND ASTRONOMY GRANT
Galaxy mergers have long been proposed as a possible mechanism to fuel the growth of super massive black holes, given their effectiveness in dissipating angular momentum and funneling gas to the center of galaxies. During summer research internships, Colby students have worked with Professor Dale Kocevski to find the missing link between galactic merger activity in the early universe and recent black hole growth.
“This is probably the biggest question in astronomy…What quenches the star formation activity of a galaxy?”
— Dale Kocevski, Assistant Professor of Physics and Astronomy
Thanks to two NASA grants, Elizabeth McGrath, the Clare Boothe Luce Assistant Professor of Physics and Astronomy, and her colleague Dale Kocevski, Assistant Professor of Physics and Astronomy, are able to study what interests them most about the life of our universe.
McGrath, who alongside Kocevski received a Ph.D. in Astronomy from the University of Hawaii at Manoa, studies galaxy formation and evolution. Kocevski, on the other hand, studies black holes and how they regulate galactic life and death. “This is probably the biggest question in astronomy,” said Kocevski. “What quenches the star formation activity of a galaxy?”
While a graduate student at the University of Hawaii in 2008, McGrath was one of the first to notice that an accepted theory in astronomy, that the formation of massive galaxies 10 times larger than the Milky Way occurred through the absorption of smaller galaxies over billions of years, was not entirely supported by recent Hubble photographs. The theory asserted that these massive galaxies, which are spherical in shape, underwent structural changes while and after merging with smaller disk-shaped galaxies.
The Hubble images, however, showed that there were massive disk-shaped galaxies that had gone through their life and death cycle; the death cycle for a galaxy occurs once star formation ceases to continue.
Through CANDELS, the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, McGrath’s initial observations are being supported and models are being developed to reproduce these never-before-seen phenomena.
At the same time, Kocevski’s research focuses on the massive black holes at the centers of galaxies. These black holes are typically a billion times more massive than stars like the sun. Referred to as “active galactic nuclei,” some of these black holes are so massive that they absorb gases and stars, consequently emitting enormous amounts of energy.
The two NASA grants, totaling $400,000, gave Kocevski access to newly available X-ray imaging from the Chandra Space Telescope and to observation time on the Hubble Space Telescope to capture images of the black holes of colliding galaxies. Kocevski’s Hubble award allowed for 30 orbits. Along with a Colby student researcher, Kocevski and the student studied and classified the image.
“Here I feel like what I do matters. The teaching—people appreciate that.”
— Elizabeth McGrath, Clare Boothe Luce Assistant Professor of Physics and Astronomy
McGrath and Kocevski have been incredible additions to Colby’s faculty, respectively arriving in 2012 and 2014 after conducting postdoctoral research at the University of California, Santa Cruz. McGrath and Kocevski have given Colby access to what is typically reserved for large, prestigious research universities.
Receiving her bachelor’s degree at Vassar, McGrath understands the value of a liberal arts education for both the student and the faculty, saying, “Here I feel like what I do matters. The teaching—people appreciate that.”