Accurate measurements of the dust properties in the 1 billion year old universe

Barišić, Ivana (2016) Accurate measurements of the dust properties in the 1 billion year old universe. Diploma thesis, Faculty of Science > Department of Physics.

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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.

Item Type: Thesis (Diploma thesis)
Keywords: dust properties in universe, galaxies
Supervisor: Smolčić, Vernesa
Co-supervisor: Capak, Peter
Date: 13 July 2016
Number of Pages: 37
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: Embargo na puni tekst diplomskog rada do 13.7.2017.
Divisions: Faculty of Science > Department of Physics
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 01 Sep 2016 08:57
Last Modified: 19 Jan 2017 13:32

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