Studying gas flows in the SUNBIRD starburst galaxies and LIRGs
| dc.contributor.advisor | Mogotsi, Keoikantse | |
| dc.contributor.author | Janse, Van Rensburg Petronella | |
| dc.date.accessioned | 2026-06-25T10:23:03Z | |
| dc.date.available | 2026-06-25T10:23:03Z | |
| dc.date.issued | 2026 | |
| dc.date.updated | 2026-06-25T10:19:28Z | |
| dc.description.abstract | Context: Gas flows are an important aspect of feedback and the regulation of star formation in galaxies. Star formation can be enhanced or quenched depending on the gas flow into and out of the galaxy, respectively. Nearby starburst galaxies and luminous infrared galaxies provide extreme environments where feedback and the changes due to it can be studied in great detail. Under- standing the gas flows in these galaxies will help us to understand galaxy evolution better. Aim: This thesis aims to study the resolved gas flows in a sample of 12 nearby (0.0073 ≤ z ≤ 0.0322) starburst galaxies and luminous infrared galaxies in the SUperNovae and starburst in the InfraReD (SUNBIRD) survey. We identify non-circular gas flows (including inflows and outflows), characterize them and study how they relate to galaxy properties using observations of the multi-phase gas (neutral and ionized) kinematics and stellar kinematics. The galaxies range from isolated to interacting, they have infrared luminosities between 1010.76L and 1011.81L and infrared star formation rates between 100.99M yr−1 and 102.04M yr−1. Method: The 12 SUNBIRD galaxies were studied with long-slit spectra from the Southern African Large Telescope. The multi-phase nature of the gas was studied by investigating the stellar con- tinuum and emission and absorption lines. The ionized gas was studied by modelling the Hα emission with multiple components of Gaussian and Gaussian-Hermite functions, and the neutral gas was studied by modelling the NaD absorption lines with a single Gaussian function. The stellar continuum was modelled with pPXF to extract the stellar kinematics and compare it to the gas kinematics. Non-circular gas flows were identified by performing multi-component fitting and looking at the offsets between the ionized gas kinematics and the neutral gas kinematics or stellar kinematics. Results: We find evidence of ionized and neutral non-circular gas flows (which includes outflows, inflows and extraplanar gas) in all 12 galaxies at varying velocities. The first ever measurements of gas flows were made for five galaxies (ESO 428-G023, ESO 550-IG025, IRAS 18293-3413, NGC 1819 and NGC 3508). The non-circular gas flow velocities of the 12 galaxies range between 35-182 km/s for the ionized gas and 61-403 km/s for the neutral gas and originate from the nucleus for most of the galaxies. We found that the strongest non-circular gas flows are due to galaxy inter- actions or the presence of a possible AGN. The velocities and their relation to the star formation rate and interaction stage are in agreement with studies of other nearby luminous infrared galaxies with the same infrared luminosity, observed through long-slit and integral field spectroscopy. We also find one galaxy (NGC 6000) with a slightly larger ionized gas velocity dispersion in the broad component (269 km/s). In addition, if we assume the non-circular gas flows are outflows, the neutral and ionized gas will not be able to escape the galaxy but remain within the galaxy halo for all 12 galaxies. This gas could possibly cool and fall down into the disk to form more stars. This suggests that for these starburst galaxies and LIRGs, even though their star-formation rate is enhanced and gas is flowing outwards, star formation is not necessarily quenched by this, and could continue in future via the galactic fountain model. | |
| dc.identifier.apacitation | Janse, V. R. P. (2026). <i>Studying gas flows in the SUNBIRD starburst galaxies and LIRGs</i>. (). University of Cape Town ,Faculty of Science ,Department of Astronomy. Retrieved from http://hdl.handle.net/11427/43386 | en_ZA |
| dc.identifier.chicagocitation | Janse, Van Rensburg Petronella. <i>"Studying gas flows in the SUNBIRD starburst galaxies and LIRGs."</i> ., University of Cape Town ,Faculty of Science ,Department of Astronomy, 2026. http://hdl.handle.net/11427/43386 | en_ZA |
| dc.identifier.citation | Janse, V.R.P. 2026. Studying gas flows in the SUNBIRD starburst galaxies and LIRGs. . University of Cape Town ,Faculty of Science ,Department of Astronomy. http://hdl.handle.net/11427/43386 | en_ZA |
| dc.identifier.ris | TY - Thesis / Dissertation AU - Janse, Van Rensburg Petronella AB - Context: Gas flows are an important aspect of feedback and the regulation of star formation in galaxies. Star formation can be enhanced or quenched depending on the gas flow into and out of the galaxy, respectively. Nearby starburst galaxies and luminous infrared galaxies provide extreme environments where feedback and the changes due to it can be studied in great detail. Under- standing the gas flows in these galaxies will help us to understand galaxy evolution better. Aim: This thesis aims to study the resolved gas flows in a sample of 12 nearby (0.0073 ≤ z ≤ 0.0322) starburst galaxies and luminous infrared galaxies in the SUperNovae and starburst in the InfraReD (SUNBIRD) survey. We identify non-circular gas flows (including inflows and outflows), characterize them and study how they relate to galaxy properties using observations of the multi-phase gas (neutral and ionized) kinematics and stellar kinematics. The galaxies range from isolated to interacting, they have infrared luminosities between 1010.76L and 1011.81L and infrared star formation rates between 100.99M yr−1 and 102.04M yr−1. Method: The 12 SUNBIRD galaxies were studied with long-slit spectra from the Southern African Large Telescope. The multi-phase nature of the gas was studied by investigating the stellar con- tinuum and emission and absorption lines. The ionized gas was studied by modelling the Hα emission with multiple components of Gaussian and Gaussian-Hermite functions, and the neutral gas was studied by modelling the NaD absorption lines with a single Gaussian function. The stellar continuum was modelled with pPXF to extract the stellar kinematics and compare it to the gas kinematics. Non-circular gas flows were identified by performing multi-component fitting and looking at the offsets between the ionized gas kinematics and the neutral gas kinematics or stellar kinematics. Results: We find evidence of ionized and neutral non-circular gas flows (which includes outflows, inflows and extraplanar gas) in all 12 galaxies at varying velocities. The first ever measurements of gas flows were made for five galaxies (ESO 428-G023, ESO 550-IG025, IRAS 18293-3413, NGC 1819 and NGC 3508). The non-circular gas flow velocities of the 12 galaxies range between 35-182 km/s for the ionized gas and 61-403 km/s for the neutral gas and originate from the nucleus for most of the galaxies. We found that the strongest non-circular gas flows are due to galaxy inter- actions or the presence of a possible AGN. The velocities and their relation to the star formation rate and interaction stage are in agreement with studies of other nearby luminous infrared galaxies with the same infrared luminosity, observed through long-slit and integral field spectroscopy. We also find one galaxy (NGC 6000) with a slightly larger ionized gas velocity dispersion in the broad component (269 km/s). In addition, if we assume the non-circular gas flows are outflows, the neutral and ionized gas will not be able to escape the galaxy but remain within the galaxy halo for all 12 galaxies. This gas could possibly cool and fall down into the disk to form more stars. This suggests that for these starburst galaxies and LIRGs, even though their star-formation rate is enhanced and gas is flowing outwards, star formation is not necessarily quenched by this, and could continue in future via the galactic fountain model. DA - 2026 DB - OpenUCT DP - University of Cape Town KW - SUNBIRD KW - LIRGs LK - https://open.uct.ac.za PB - University of Cape Town PY - 2026 T1 - Studying gas flows in the SUNBIRD starburst galaxies and LIRGs TI - Studying gas flows in the SUNBIRD starburst galaxies and LIRGs UR - http://hdl.handle.net/11427/43386 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/43386 | |
| dc.identifier.vancouvercitation | Janse VRP. Studying gas flows in the SUNBIRD starburst galaxies and LIRGs. []. University of Cape Town ,Faculty of Science ,Department of Astronomy, 2026 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/43386 | en_ZA |
| dc.language.iso | en | |
| dc.language.rfc3066 | eng | |
| dc.publisher.department | Department of Astronomy | |
| dc.publisher.faculty | Faculty of Science | |
| dc.publisher.institution | University of Cape Town | |
| dc.subject | SUNBIRD | |
| dc.subject | LIRGs | |
| dc.title | Studying gas flows in the SUNBIRD starburst galaxies and LIRGs | |
| dc.type | Thesis / Dissertation | |
| dc.type.qualificationlevel | Doctoral | |
| dc.type.qualificationlevel | PhD |