Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 2036 Galaxies in the epoch of reionization Investigating the high-redshift galaxy population through simulations and observations CHRISTIAN BINGGELI ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 ISBN 978-91-513-1196-8 UPPSALA urn:nbn:se:uu:diva-440032 2021 Dissertation presented at Uppsala University to be publicly examined in Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, Thursday, 10 June 2021 at 13:15 for the degree of Doctor of Philosophy. The examination will be conducted in English. Faculty examiner: Stephen Wilkins (University of Sussex). Online defence: https://uu-se.zoom.us/j/68040940351 Abstract Binggeli, C. 2021. Galaxies in the epoch of reionization. Investigating the high-redshift galaxy population through simulations and observations. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 2036. 87 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-513-1196-8. The cosmic reionization is the last major gas phase transition in cosmic history, yet it remains poorly understood. Current constraints indicate that early star-forming galaxies drove the reionization process through producing and releasing large numbers of ionizing photons into the intergalactic medium. However, our understanding of the ionizing escape fraction (fesc) and the general properties of high-redshift galaxies is still limited. In this thesis, simulated galaxies and observations are used to investigate epoch-of- reionization galaxies and to explore methods that can aid future investigations of such objects. Using simulations, we have shown that it may be possible to constrain fesc in epoch-of- reionization galaxies using quite simple diagnostics that should be observable with the upcoming James Webb Space Telescope (JWST). We also show that variations in star formation activity larger than those predicted in our simulations may lead to a possible degeneracy with high fesc. However, auxiliary information obtained with the JWST may allow us to disentangle variations in the star formation activity from high fesc. We compare galaxies from several simulations to the recently spectroscopically confirmed z=9.1096 galaxy MACS1149-JD1. We find that none of the simulations are able to reproduce the large Balmer break observed in MACS1149-JD1, and argue that unless it represents an outlier in the high-redshift galaxy population, this may indicate that the simulations fail to capture some key physics. Finally, we present ALMA observations of the z=7.6637 galaxy z7_GSD_3811. This object remains undetected in several commonly detected FIR emission lines and FIR dust emission. Using SED-fitting and by comparing our observations to models and low-redshift observations, we show that our non-detections could indicate that the object is poor in metals and dust. Our findings could help future observers to further constrain the nature of high-redshift galaxies and their role in reionization. Keywords: galaxies: high-redshift, galaxies: ISM, galaxies: evolution, reionization, Lyman continuum Christian Binggeli, Department of Physics and Astronomy, Observational Astronomy, 516, Uppsala University, SE-751 20 Uppsala, Sweden. © Christian Binggeli 2021 ISSN 1651-6214 ISBN 978-91-513-1196-8 urn:nbn:se:uu:diva-440032 (http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-440032) Till Linnéa List of papers This thesis is based on the following papers, which are referred to in the text by their Roman numerals. I Zackrisson, E., Binggeli, C., Finlator, K.; Gnedin, N. Y., Paardekooper, J.-P., Shimizu, I., Inoue, A. K., Jensen, H., Micheva, G., Khochfar, S. and Dalla Vecchia, C. (2017) The spectral evolution of the first galaxies. III. Simulated James Webb Space Telescope spectra of reionization-epoch galaxies with Lyman-continuum leakage The Astrophysical Journal 836, 78 II Binggeli, C., Zackrisson, E., Pelckmans, K., Cubo, R., Jensen, H. and Shimizu, I. (2018) Lyman continuum leakage versus quenching with the James Webb Space Telescope: The spectral signatures of quenched star formation activity in reionization-epoch galaxies Monthly Notices of the Royal Astronomical Society 479, 368-376 III Binggeli, C., Zackrisson E., Ma, X., Inoue A. K., Vikaeus, A., Hashimoto, T., Mawatari, K., Shimizu, I. and Ceverino D. (2019) Balmer breaks in simulated galaxies at z>6 Monthly Notices of the Royal Astronomical Society 489, 3827-3835 IV Binggeli, C., Inoue, A. K., Hashimoto, T, Toribio, M. C., Zackrisson, E., Ramstedt, S., Mawatari, K., Harikane, Y., Matsuo, H., Okamoto, T., Ota, K., Shimizu, I., Tamura, Y., Taniguchi, Y. and Umehata, H. (2021) A puzzling non-detection of [O III] and [C II]fromaz≈ 7.7 galaxy observed with ALMA Astronomy & Astrophysics 646, A26 Reprints were made with permission from the publishers. Errata I Zackrisson, E., Binggeli, C., Finlator, K.; Gnedin, N. Y., Paardekooper, J.-P., Shimizu, I., Inoue, A. K., Jensen, H., Micheva, G., Khochfar, S. and Dalla Vecchia, C. (2021) Erratum: The spectral evolution of the first galaxies. III. Simulated James Webb Space Telescope spectra of reionization-epoch galaxies with Lyman-continuum leakage The Astrophysical Journal 908, 116 II Binggeli, C., Zackrisson, E., Pelckmans, K., Cubo, R., Jensen, H. and Shimizu, I. (2020) Erratum: Lyman continuum leakage versus quenching with the James Webb Space Telescope: The spectral signatures of quenched star forma- tion activity in reionization-epoch galaxies Monthly Notices of the Royal Astronomical Society 496, 1766-1767 List of papers not included in the thesis The following are publications to which I have contributed as author, but which are not included in the thesis. 1 Sugahara, Y., Inoue, A. K., Hashimoto, T. et al. (2021) Big Three Dragons: A [N II] 122 μm Constraint and New Dust- continuum Detection ofAz=7.15 Bright Lyman Break Galaxy with ALMA Submitted to The Astrophysical Journal 2 Vikaeus, A., Zackrisson, E. and Binggeli, C., (2020) The impact of star formation sampling effects on the spectra of lensed z > 6 galaxies detectable with JWST Monthly Notices of the Royal Astronomical Society 492, 1706-1712 3 Zackrisson, E., Majumdar, S., Mondal, R. et al. (2020) Bubble mapping with the Square Kilometer Array-I. Detecting galaxies with Euclid, JWST, WFIRST and ELT within ionized bubbles in the in- tergalactic medium at z> 6 Monthly Notices of the Royal Astronomical Society 493, 855-870 4 Giri, S. K., Zackrisson, E., Binggeli, C., Pelckmans, K. and Cubo, R. (2020) Identifying reionization-epoch galaxies with extreme levels of Lyman continuum leakage in James Webb Space Telescope surveys Monthly Notices of the Royal Astro nomical Society 491 5277-5286 5 Tamura, Y., Mawatari, K., Hashimoto, T. et al. (2019) Detection of the Far-infrared [O III] and Dust Emission in a Galaxy at Redshift 8.312: Early Metal Enrichment in the Heart of the Reionization Era The Astrophysical Journal 874, 27 6 Jensen, H., Zackrisson, E., Pelckmans, K., Binggeli, C.., Ausmees, K. and Lundholm, U., (2016) A Machine-learning Approach to Measuring the Escape of Ionizing Ra- diation from Galaxies in the Reionization Epoch The Astrophysical Journal 827, 5 Contents 1 Introduction ................................................................................................ 13 2 Hydrogen and Lyman continuum radiation ............................................. 15 3 Cosmic reionization ................................................................................... 17 3.1 Constraints on reionization ............................................................ 18 3.1.1 Constraints from quasars ................................................. 18 3.1.2 Constraints from the cosmic microwave background ... 20 3.1.3 Constraints from Lyman-α emitters ............................... 22 3.2 Driving sources of cosmic reionization ........................................ 23 4 Properties of high-redshift star-forming galaxies .................................... 25 4.1 Dust properties ............................................................................... 25 4.2 Star formation ................................................................................. 29 4.3 Far-infrared observations and the interstellar medium ................ 31 5 The Lyman continuum escape fraction .................................................... 36 5.1 Mechanisms of Lyman continuum leakage .................................. 37 5.2 Observations of leaking Lyman continuum .................................. 38 5.3 Indirect methods for constraining the escape fraction ................. 39 5.3.1 Emission-line constraints on the escape fraction ........... 39 5.3.2 Absorption-line constraints on the escape fraction ....... 41 5.3.3 Escape fractions from ionized proximity-zones and bubbles ............................................................................. 41 5.3.4 Zackrisson et al. 2013: Nebular emission features ....... 42 6 Synthetic spectra of high-redshift galaxies .............................................. 46 6.1 Population synthesis and model galaxy spectra ........................... 46 6.2 Simulated galaxies ......................................................................... 47 6.3 Spectra of simulated galaxies ........................................................ 49 7 Radio interferometry and interferometric imaging ................................. 53 8 Summary of papers ...................................................................................