VLA-COSMOS 3 GHz Large Project

doctoral thesis

• Title: VLA-COSMOS 3 GHz Large Project : Star formation through cosmic time
• Title (croatian): VLA-COSMOS 3 GHz Large Project : Stvaranje zvijezda kroz kozmičko vrijeme
• Author: Mladen Novak
• Mentor: Vernesa Smolčić (mentor)
• Committee member: Ana Babić (predsjednik povjerenstva)
• Committee member: Krešimir Pavlovski (član povjerenstva)
• Committee member: Vernesa Smolčić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2017-12-18, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics
• Universal decimal classification (UDC): 53 - Physics

Abstract

Radio continuum emission from approximately ten thousand galaxies was observed at 3 GHz (10 cm) and used to trace galaxy evolution and the dust unbiased cosmic star formation rate history since the universe was only 1 billion years old. Observations lasting almost 400 hours were performed with the upgraded Karl G. Jansky Very Large Array (VLA) interferometer pointed toward the 2 square degree equatorial COSMOS field. This VLA-COSMOS 3 GHz Large Project represents the currently deepest radio continuum observations performed across such a large area of the sky. Radio sources were paired with optical/near-infrared counterparts and a statistical approach was used to determine luminosity functions of two main galaxy populations: star-forming galaxies and active galactic nuclei. Number counts of radio galaxies were obtained, which suggest that the future deep radio surveys will predominantly observe star-forming galaxies. The redshift dependent infrared-radio correlation was used to link radio emission with star formation processes. This research suggests that galaxies were the most productive when the universe was 2.5 billion years old (at a redshift of z ~ 2:5), only a fifth of its current age. During that period, about 25% of all newborn stars were being created in massive galaxies where star formation rates can reach thousands of solar masses per year. Up to 20% more star formation might be occurring in highly dust obscured galaxies in the early universe, compared to what was previously thought.

Abstract (croatian)

Cilj ovog rada je pomoću dubokih radio opažanja pratiti evoluciju galaksija te odrediti kozmičku povijest stvaranja zvijezda od trenutka kad je svemir bio star otprilike jednu milijardu godina. U tu su svrhu napravljena radio opažanja u trajanju od gotovo 400 sati pomoću Karl G. Jansky Very Large Array (VLA) radio interferometra uperenog u COSMOS ekvatorijalno polje na nebu veličine dva kvadratna stupnja. Ova opažanja su dio VLA-COMOS 3 GHz velikog projekta (engl. Large Project) te predstavljaju trenutno najdublja mjerenja radio kontinuuma učinjena preko površine veće od jednog kvadratnog stupnja. Dugo trajanje mjerenja i površina COSMOS polja omogućavaju opažanje dovoljno velikog uzorka galaksija potrebnog za ovakvu vrstu analize. Prednost radio opažanja leži u činjenici da radio valovi ne međudjeluju sa sredinom kroz koju prolaze te se dobivaju opažanja bez utjecaja prašine koja inače zatamnjuje svjetlost kraćih valnih duljina.

• Keywords: galaxies; galaxy evolution; radio emission; interferometry; luminosity function; star formation; cosmic star formation history; active galactic nuclei; COSMOS field; Very Large Array
• Keywords (english): galaksije; evolucija galaksija; radio zračenje; interferometrija; funkcija luminoziteta; stvaranje zvijezda; kozmička povijest stvaranja zvijezda; aktivna galaktička jezgra; COSMOS polje; Very Large Array
• Language: english
• URN:NBN: urn:nbn:hr:217:195872
• Study programme: Title: Physics; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika (doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika)
• Type of resource: Text
• Extent: XXII, 169 str.
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-01-04 10:36:20