The effects of feedback on the escape of radiation in star-forming dwarf galaxies
Title: The effects of feedback on the escape of radiation in star-forming dwarf galaxies
DNr: NAISS 2023/5-439
Project Type: NAISS Medium Compute
Principal Investigator: Göran Östlin <>
Affiliation: Stockholms universitet
Duration: 2023-11-30 – 2024-12-01
Classification: 10305


According to contemporary cosmological models, dwarf galaxies are the first structures to form that can sustain stellar formation for a substantial amount of time. Star-forming dwarf galaxies have long been considered one of the dominant contributors of ionising radiation during the Epoch of Reionisation, a period during the early Universe where it transitioned from being completely radiation opaque to transparent. However, the process of how this radiation escapes the galaxy and ionises the Universe is not completely understood. A popular contender for facilitating the escape of radiation from the galaxy is stellar feedback, i.e. radiation from stars, stellar winds and supernova explosions. The exact impact of these effects is not currently known but can be explored via kinematic signatures, e.g. outflows and ionised diffuse regions. An important quantity for reionisation is the escape fraction, which is simply the amount of (ionising) radiation able to leave the galaxy. This parameter varies drastically between emission lines and individual galaxies. Because of this, studies of high star-forming (starburst) dwarf galaxies are an ongoing and popular research field. However, due to a number of observational difficulties, there are few detections of galaxies this far back in time. Instead, detailed observations can be obtained from local analogues, i.e. low-redshift galaxies with similar properties, to infer knowledge about the formation and evolution of the first dwarf galaxies. Furthermore, numerical simulations allow us to alter the physics within the galaxy and analyse in detail the dynamics and physical processes present in these galaxies. For this project, we will model entire dwarf galaxies with similar properties to local analogues, using the hydrodynamical + N-body code RAMSES. This yields another perspective from which to make direct comparisons with observational data. We aim to explore kinematic signatures and correlations between galactic parameters to better understand how stellar feedback facilitates the escape of (ionising) radiation. With our previous SNIC allocations, we explored a large set of initial conditions of a galaxy merger between two galaxies at low resolutions. This allowed us to pinpoint the initial conditions of simulations with large-scale structures which best fit the available observational data. Our primary intention with this allocation is to run these simulations at a high resolution and investigate the small-scale structures of this galaxy.