Institute of Astronomy

Spectroscopic studies of star-forming galaxies in the Epoch of Reionisation

SpeakerTalk DateTalk Series
Joris Witstok27 October 2021Institute of Astronomy Seminars


In this talk, I will firstly present a spectroscopic case study of a 30× lensed galaxy at z=5. Detections of the C IV and [Ne III] lines allow us to constrain the origin of the hard radiation field, the ionisation parameter, and the metallicity, while observed Mg II emission might prove a key tracer of escaping ionising radiation for JWST. Before JWST, however, we can already spectroscopically probe galaxies in the Epoch of Reionisation (EoR) with ALMA, whose recent detections of the far-infrared [CII] 158 μm and [OIII] 88 μm emission lines have opened a new observational window for studying galaxies at the highest redshift. In this talk, I will furthermore present new [OIII] 88 μm observations of four galaxies at z=7 recently detected by ALMA in [CII], allowing a multi-wavelength comparison combined with new deep HST images of the rest-frame UV. The [OIII] emission, corresponding to diffuse, highly ionised gas, and [CII] emission, tracing neutral gas and photon dissociation regions, allow some of the first explorations of the interstellar medium in the EoR.


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