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
SNIC Project: SNIC 2020/14-67
Project Type: SNIC Small Storage
Principal Investigator: Göran Östlin <>
Affiliation: Stockholms universitet
Duration: 2020-11-01 – 2021-10-01
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 of facilitating the escape of radiation from the galaxy is stellar feedback, i.e. radiation from stars, stellar winds and supernova explosion. 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. Studies of high star-forming (starburst) dwarf galaxies are currently a popular ongoing 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 process 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, coupled with radiative transfer equations. We intend to simulate galaxies with a set of around 10 initial conditions, including ICs with merger between two galaxies. The purpose is to find new and confirm existing correlations that can be applied to observational data of analogue galaxies to predict properties and relations, such as the escape fraction, which are commonly not well constrained or understood.