The star formation histories of Lyman-alpha emitters at z = 3 − 7

Ceban, Daniil (2024) The star formation histories of Lyman-alpha emitters at z = 3 − 7. Bachelor's Thesis, Astronomy.

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Abstract

Ly-α emitting galaxies (LAEs) are usually detected via their intense UV emission lines, thus generally considered blue, low-mass objects. However, recent studies have revealed the presence of an older population in a significant fraction of these objects (≈ 30%), which raises a question about their true evolutionary path. We consider a sample of 182 Ly-α emitters at z ≈ 3 − 7. Using photometry from 27 bands provided by both HST and JWST, we perform spectral energy distribution (SED) fitting using CIGALE. We examine the stellar population properties across four star formation history (SFH) types: exponential decline, and delayed exponential with no burst, mandatory burst or optional burst in star formation. We compare the resulting physical properties (Age, M∗, SFR) and discuss the implications in the context of the relative placement of our LAEs along the main-sequence of starforming galaxies. Across all models, we find a consistent fraction of young (≤ 100 Myrs) LAEs, constituting roughly 80% of the sample. When no burst is included, young LAEs are mostly low-mass systems with high star formation rates, leading to a clear specific star formation (sSFR) bimodality between young and older (> 100 Myrs) objects. As a result, young LAEs are classified as starbursts. Incorporating a bursty SFH shows that 85% of our LAEs tend to fit a recent burst, reducing the degree of starburst trend among young objects. However, our χ2 analysis shows no preference towards either SFH.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Caputi, K.I. and Iani, E.
Degree programme:	Astronomy
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	16 Jul 2024 11:10
Last Modified:	16 Jul 2024 11:10
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/33440

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