Anotace
As galaxies are formed, to a large extent, by merging of smaller galaxies, knowing the merger history of the observed galaxies is
crucial to understand their evolution as well as the evolution of the whole Universe. Galaxy mergers are slow processes, happening
over millions of years and so the information about the merger history of any individual galaxy must be indirectly derived from its
present-day state. Luckily, a significant portion of elliptical and lenticular galaxies show a unique type of fine structure known as
stellar shells, which are created in mergers and can be used to date the last significant merger that the galaxy has undergone.
We have already developed methods to extract such information from individual galaxies. Now we will expand the applicability of
such methods to vastly larger samples. To this end, we will develop a set of self-contained tools to identify and analyze shell galaxies
in images of large sky surveys, so that the estimates of merger times can be automatically obtained. We will apply those tools on
existing data from current surveys and prepare for their application to the unprecedentedly large data set that will be produced by
the Large Survey of Space and Time (LSST) at the Vera C. Rubin Observatory, which will become operational around the time when
the project concludes.
This will transform shell galaxies from a position of curiosity to that of utility, allowing statistical applications using the merger data on
the hundreds of shell galaxies that will be identified in the existing data and later on the thousands of galaxies eventually observed by
the LSST project – a huge qualitative leap from the handful of galaxies with known merger histories available today. We will pioneer
the use of this data by applying it for the benefit of LSST itself, where it will help optimize the observation time in search of transients
by exploring the correlation of their occurrence with the merger histories of the host galaxies.