Precizna mjerenja svojstava prašine galaksija u svemiru starom 1 milijardu godina

master's thesis

• Title (english): Accurate measurements of the dust properties in the 1 billion year old Universe
• Author: Ivana Barišić
• Mentor: Vernesa Smolčić (mentor)
• Mentor: Peter Čapak (mentor)
• Committee member: Vernesa Smolčić (predsjednik povjerenstva)
• Committee member: Ivica Smolić (član povjerenstva)
• Committee member: Mirko Planinić (član povjerenstva)
• Committee member: Hrvoje Buljan (član povjerenstva)
• Committee member: Krešimir Pavlovski (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2016-07-13, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

U ovom radu proučavam svojstva atenuacije prašine 11 galaksija, sa prosječnim stupnjem formiranja novih zvijezda, na crvenom pomaku 5 < z < 6 u COSMOS polju koristeći Hubble Space Telescope Wide Field Camera 3 (HST WFC-3) podatke visoke rezolucije u ultaljubičastom dijelu spektra u sustavu mirovanja galaksija. Također, koristim podatke u daleko - infracrvenom (FIR) kontinuumu i [CII] emisijske linije opažene sa Atacama Large Millimeter Array (ALMA). U prijašnjem radu za isti skup galaksija, gdje koriste podatke niskog omjera signala - prema - šumu pronađeno je da ove galaksije imaju veće vrijednosti ultraljubičastih (UV) spektralnih nagiba za fiksne vrijednosti omjera FIR i UV luminoziteta, u odnosu na galaksije u lokalnom svemiru. Ta razlika je mogla biti uzrokovana sistematskim efektima u mjerenjima infracrvenog luminoziteta i UV spektralnih nagiba, ili pak promjenama u geometriji prašine ili dinamici u galaksijama na visokom crvenom pomaku. Koristeći podatke visokih omjera signal - prema - šumu dobila sam konzistentne UV spektralne nagibe sa vrijednostima dobivenim u prijašnjem radu. Ovaj rezultat pokazuje da se razlika između galaksija na visokom i niskom crvenom pomaku može pripisati drugačijim svojstvima prašine i plina u galaksijama na visokom crvenom pomaku (z > 5). No, sa mojim novim mjerenjima i dodatnim testovima njihove pouzdanosti i preciznosti, zaključujem da dio galaksija na visokom crvenom pomaku pokazuje slična svojstva prašine galaksijama na niskom crvenom pomaku. Unatoč tome, to nije slučaj za podskup mog seta galaksija koje pokazuju vrlo niske omjere FIR prema UV luminozitetima, ukazujući tako na drugačija svojstva plina i prašine prisutna u tim galaksijama.

Abstract (english)

In this work I examine the dust attenuation properties of 11 average star-forming galaxies at high redshift 5 < z < 6 in the COSMOS field using deep high resolution rest-frame ultraviolet (UV) Hubble Space Telescope Wide Field Camera 3 (HST WFC-3) data along with far - infrared (FIR) continuum and [CII] emission line measurements from the Atacama Large Millimeter/Submillimeter Array (ALMA). In the previously conducted study of the same sample of galaxies, using low signal-to-noise ground based telescope data, it was found that these galaxies have higher dust column densities, i.e. redder UV continuum slopes, at a fixed FIR to UV luminosity ratio, compared to the average of local galaxies. This apparent difference is either caused by systematic measurement biases in the infrared luminosity and ultraviolet slope estimates, or changes in dust geometry or gas dynamics in high redshift galaxies. With the high signal-to-noise HST WFC-3 data I find mainly consistent UV continuum slope values compared to the ones from the low signal-to-noise ground based data. This result shows that differences between galaxies at low and high redshift found in previous studies are due to different dust and gas properties in high redshift (z > 5) galaxies. With HST WFC-3 measurements and additional tests of their reliability and accuracy, I conclude that some of the high redshift galaxies show similar dust attenuation properties as low redshift galaxies. However, I find that this is not the case for the upper limit subset of our sample showing very low FIR to UV luminosity ratios, hinting towards different dust and gas properties.

• Keywords: svojstva prašine u svemiru; galaksije
• Keywords (english): dust properties in universe; galaxies
• Language: croatian
• URN:NBN: urn:nbn:hr:217:114701
• Study programme: Title: Physics; specializations in: Research; Course: Research; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra fizike (magistar/magistra fizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 2017-07-13
• Created on: 2017-03-03 11:09:48