Astronomy and Astrophysics

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The most massive galaxies of the early universe are different from their descendants observed in our galactic neighbourhood. When they stop forming stars, these distant "island universes" contain at least as many stars as the Milky Way. However, their stars are packed into volumes thousands of times smaller than the volume of the Milky Way. Theoretical models of galaxy formation and evolution predict that these dense systems should grow through mergers and interactions with other galaxies as the universe matures.Galaxy surveys that cover large volumes and include both dense spectroscopy and high-quality imaging are uniquely suited to map out how today's galaxies assemble their mass. As CRC in Astronomy and Astrophysics Dr. Damjanov uses this synergy to probe the relations between galaxy size growth, the changes in their stellar and (invisible) dark matter content, and their position within the web that the invisible cosmic material weaves throughout the universe. She has discovered that the average rate at which galaxies grow in size after they cease forming stars depends critically on galaxy mass. Combining the observations of galaxies in the nearby and in more distant (and thus earlier) universe, she has demonstrated that massive galaxies indeed grow preferentially through mergers with less massive systems. Proposed research will take current spectroscopic surveys with high-resolution imaging to the next level by including hundreds of thousands of galaxies observed to distances and cosmic times when the universe was half of its current age. Dr. Damjanov will probe how the way galaxies grow changes depending on their location with respect to the cosmic web. She will employ innovative techniques based on artificial intelligence to comb through vast volumes of galaxy images and construct the largest to-date samples of galaxies with signatures of resent mergers in their light profiles. Studying these peculiar galaxies will unveil the types of gravitational interactions that shape them. Massive clusters of galaxies that illuminate knots of the cosmic web harbour large amounts of dark matter. This invisible mass bends the light coming from larger distances, distorting (and even multiplying) galaxy images into arc-like shapes. Dr. Damjanov will study these signatures in galaxy clusters from her survey to trace, in the most direct way possible, simultaneous evolution of luminous and invisible matter throughout the second half of cosmic history.