Research
I am curious about how the Universe works, by applying logical thinking.
PhD Thesis
I have finished the PhD Astronomy program (thesis link here) in 2024 from the University of Turku, where I focused on using observations to look at the galaxies in proximity to active galaxies.
My work is impactful because
- it is based on observational data, which provides a real life check to the simulations and theories about galaxy formation;
- furthermore, the results are intriguing because for these low-redshift quasars, it appears that the major mergers (a popular theory) is not the main triggering and feeding mechanism of the central SMBH, but rather the instabilities within the galaxy itself, aka the ‘secular scenario’ is a better explanation and it means that no external influence by a equally massive galaxy is necessary. On the other hand, minor mergers could be also one additional avenue for triggering the AGN.
Active galaxies …
… are galaxies with actively accreting supermassive black holes.
They are not only cool because they have enormous black holes in them – a singularity phenomenon with its amazing physics, but also as observational objects, because
- they radiate photons in all wavelengths of the electromagnetic spectrum,
- they can be extremely bright
- they may be extremely variable, just to name a few signatures.
It is thought that active galaxies have an important role in the formation and evolution of galaxies through cosmic time.
In my first first-author paper, Stone et al. 2021 MNRAS, I used spectroscopy from the Nordic Optical Telescope and Gran Tecan to estimate which candidate companion galaxies were indeed true quasar neighbors. A second set of observations was done with multi-object spectroscopy at the New Technology Telescope (Bettoni et al. 2023 MNRAS).
First main result showed that the fraction of quasars with companions was comparable to the fraction of normal galaxies (not quasars) with companions. So, we did not observe that quasars had a larger number of merger candidates in their fields.
Second main result was that the star formation rate of these companion galaxies was modest and comparable to that of random galaxies on the same images (background or foreground projections).

In my second first-author paper, Stone et al. 2023 ApJ, I used archival data from the GAMA spectroscopic survey.
The sample consisted of 205 GAMA quasars (Type I, z=0.1-0.35). For each quasar, in a comoving volume of ~2 Mpc, the bright galaxy-neighbors were identified, and their properties investigated (stellar mass, star formation rate, morphology, etc.). The same was done for comparison inactive (normal) galaxy fields, matched in redshift and in stellar mass to the quasar sample. We found that the neighbors around quasars had no statistically significant difference in their physical properties, star formation history, and demographics than the neighbors around inactive galaxies.
Currently I am continuing the investigation of the GAMA quasars, now to describe in more detail the host galaxies themselves.
