U fokusu mojih istraživanja su daleke galaksije nastale svega milijardu godina nakon Velikog praska. Neki od tih grandioznih objekata su među najmasivnjim u celom svemiru, a poreklo njihovog jakog infracrvenog zračenja još uvek zbunjuje astronome. Zbog toga, neka od pitanja na koja pokušavam da pronađem odgovore su:
Na koji način se u svemiru formiraju najmasivnije galaksije?
Kako one provode svoje živote i konzumiraju materiju od koje su sačinjene?
Koje je poreklo galaktičke prašine, osnovnog elementa organskog života?
Zašto neke galaksije grade jata, a druge provode svoj život izolovane?
Zbog njihove kompleksnosti, odgovore na ova pitanja tražim uz pomoć najvećih teleskopa kako na Zemlji, tako i u svemiru. Mnogi od tih teleskopa nalaze se na najekstremnijim mestima na Zemlji: u pustinji Atakama u Čileu, na vrhu vulkana Mauna Kea na Havajima, na Južnom polu, ili na planinama Sijera Nevade u Španiji.
Na konkursu NCN fondacije, nedavno sam osvojio individualni grant za svoj projekat "Dusty Giants". Taj grant će mi pomoći da sa timom svojih dragih saradnika sa različitih svetskih instituta istražim nove metode koje bi objasnile poreklo infracrvenog zračenja najdaljih galaksija i njhovih jata u kosmosu.
Ukoliko ste zainteresovani da saznate više o ovim projektima, ili želite da aplicirate za poziciju doktorskog studenta u mojoj grupi, pišite mi!
Linkovi ka naučnim radovima
1. Formation & evolution of distant, dusty galaxies
My research focuses on galaxy formation and evolution. In other words, I am curious about the life of galaxies in our Universe, from the earliest cosmic times after the Big Bang to the present day.
In particular, I am interested to understand the nature of the most massive and the most luminous galaxies, so-called dusty star-forming galaxies. Since their initial discovery 20 years ago, these distant and massive objects posses the serious challenge to astronomers questioning how could such large and dusty "giants" have been produced so early in the Universe.
In my research, I unite observational and theoretical methods in order to tackle some of important questions, such as: how the dust, gas and metals in galaxies evolve over cosmic time. In Donevski et al. A&A 2020, we analysed more than 300 galaxies observed with ALMA and interpreted our findings by applying several state-of-the-art cosmological models. Our research provided the first strong observational evidence of a double origin of dust in distant galaxies. That is to say, we showed that supernovae cannot be only production sources of galaxy dust, and they need to be complemented by the quick rise of dust grains in the interstellar medium!
From Donevski et al. A&A 2020:
Observed evolution of the dust-to-stellar mass ratio in 300 distant dusty galaxies. The distant galaxies are identified with ALMA in the COSMOS field.
2. Galaxy environments: simulations & observations
Today we know that clusters of galaxies are largest virialised structures in an observable Universe. However, while local clusters are well explored systems, this is not the case with their more distant progenitors. The recent theoretical models suggests that so-called protoclusters may have dominated star-formation history in the first two billion of years of cosmic time. Because of this, it is crucial to quantify how different physical properties (e.g. mass of gas, metals and dust) evolve as a function of environments over cosmic time. The NCN supported project "Dusty Giants" for which I am a PI, will give answer to this question.
Previously, as part of my doctoral work, I investigated how the most extreme infrared galaxies (so-called "500-micron risers") trace protoclusters (Donevski, PhD thesis, Donevski et al. in prep.). By creating simulated maps using different models, I found that these extreme dusty galaxies are common in distant overdensities of galaxies. The method I developed was applied to identify dust obscured galaxies clustered in some of the most distant protocluster discovered so far (z>6, Harikane et al. ApJ 2019).
Spectroscopically confirmed member galaxies of the most distant protocluster at z=6.67 (Harikane et al. 2019).
Simulated small-scale environments of 500-micron risers at z>3. This example shows that physical associations of distant galaxies in protoclusters influence observed infrared flux with Herschel instrument.
(Donevski, PhD Thesis)
3. Selection and statistical properties of dust obscured, massive galaxies at very high-redshifts (z>4)
I explore how to understand the statistical properties of distant and massive (and dusty) galaxies selected from the large extragalactic fields. In the recent past, the big part of my work was concerned with a comprehensive analysis of statistics and nature of candidate very distant (z > 4) population of sources identified with infrared/sub-mm telescopes such as Herschel, SCUBA-2 and IRAM.
In Donevski et al. A&A 2018, I presented the new technique which combines observational and theoretical techniques to select galaxies at very high-redshifts. As a result of this work, I offered to the community a catalogues of 100+ dusty galaxies behind the Virgo cluster. These galaxies reside in high-redshifts and are some of the most luminous, non-lensed star-forming systems known in the Universe.
Redshift properties of more than 100 candidate z>4 dusty galaxies identified with a novel method presented in Donevski et al. 2018.
4. Evolution of interstellar medium over cosmic times
The so-called "infrared-to-radio correlation" is one of known empirical tools which astronomers use to get insight into galaxy star-formation production. The relation is thought to originate from galaxy star-formation sites implying linear connection with a small scatter. Throughout many years, this paradigm based on initial analyses on low-z galaxies have been unchanged and empirical relation was applied "straightforwardly". However, recent findings discover significant variations in observed infrared-to-radio luminosities, and in Donevski & Prodanovic MNRAS 2015, we proposed a new physical explanation for such behaviour. Namely, we proposed that galaxy mergers and interactions in massive halos can significantly contribute to the observed IR and radio flux, based on the galaxy merging stage.