Dissertation defence (Astronomy): MSc Maria Babakhanyan Stone


11.6.2024 at 12.00 - 16.00
MSc Maria Babakhanyan Stone defends the dissertation in Astronomy titled “Galaxy evolution through the lens of active galactic nuclei, their host galaxies, and environments: an observational study” at the University of Turku on 11 June 2024 at 12.00 (University of Turku, Quantum, Auditorium, Vesilinnantie 5, Turku).

Opponent: Dr. Anna Wolter (National Institute for Astrophysics, Brera Astronomical Observatory, Italy)
Custos: Professor Emeritus Mauri Valtonen (University of Turku)

The audience can participate in the defence by remote access: https://utu.zoom.us/j/69588162281

Doctoral Dissertation at UTUPub: https://urn.fi/URN:ISBN:978-951-29-9721-3


Summary of the Doctoral Dissertation:

In this dissertation, I explore the relationship of galaxies with their surrounding cosmic environment. We live in the Milky Way Galaxy, which looks like a giant spiral. About 100 years ago, observations by a famous astronomer Edwin Hubble provided evidence that there are many other galaxies in the Universe - some look like the Milky Way, but others appear to be elliptical, dwarf, or irregular. These galaxies shine brightly in the wavelengths perceptible to the human eye due to the light from their constituent stars.

A minor fraction of galaxies exhibit interesting features, such as emitting light due to non-stellar processes from a compact area in their centers. This light can outshine the starlight of a galaxy. Such galaxies are called active galaxies, and are thought to be powered by accretion onto central black holes of colossal size - more than one hundred thousand times the mass of the Sun.

In this dissertation, we investigate what impact active galaxies have on their surroundings as well as the opposite question - how the environment affects them. Our key finding is that within several billion light year distance, the giant black holes in active galaxies are triggered due to processes inside their galaxy itself, and do not need external influence, such as interaction or merging with a neighboring galaxy. We also found that the star formation properties of galaxies close to active galaxies are similar to galaxies around normal (inactive) galaxies. So it does not matter in the life of a galaxy if its close neighbor is active or not.

This research was done by observing galaxies with several telescopes. I performed observations myself at the Nordic Optical Telescope (Canary Islands) and at the New Technology Telescope (Chile). A collaborator has observed the Gran Tecan (Canary Islands). Also, I used data from large survey archives, such as the Sloan Digital Sky Survey and the Galaxy and Mass Assembly spectroscopic survey.
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