Hı asymmetries and deficiencies in Alfalfa galaxies
| dc.contributor.author | Thobejane, Reshoketswe | |
| dc.date.accessioned | 2025-10-08T07:06:15Z | |
| dc.date.available | 2025-10-08T07:06:15Z | |
| dc.date.issued | 2025 | |
| dc.description.abstract | This work focuses primarily on the effects that the environment of a galaxy has on the asymmetries observed in the Hı profiles of galaxies. Galaxies exhibit a wide range of observable properties and the environment in which a galaxy resides is known to impact its characteristics significantly. Thus, using the ALFALFA survey, which provides ∼ 31,500 Hı spectral profiles of galaxies out to redshifts of z < 0.06, this work generates two samples (the isolated and merger sample) to provide evidence of how the environment of a galaxy is one of the main drivers of the asymmetries observed in the Hı profiles of galaxies. The galaxy’s environment in this work, is defined according to the nearest galaxy neighbour. The merger sample galaxies are those galaxies that are found to have neighbouring galaxies within 25 kpc spatially and 750 km s−1 spectrally. The isolated sample galaxies are those that are found to have no neighbouring galaxies within 750 kpc spatially and 7500 km s−1 spectrally. In total, the merger sample consists of 205 galaxies and the isolated sample of 5604 galaxies which all have signal-to-noise (SNR)> 6.5. This work finds that on average, the most asymmetric profiles are in the merger sample which leads to a strong suggestion that the environment of a galaxy is one of the main drivers of asymmetries observed in the Hı profiles of galaxies. A further investigation on environment density as a function of Hı asymmetry is employed on the full ALFALFA galaxy sample for different cluster environments. This work finds that there is a correlation between environmental density and Hı asymmetry, that is, the galaxies residing in dense environments tend to have more asymmetric Hı profiles than those galaxies residing in the less dense environments. | |
| dc.identifier.uri | https://hdl.handle.net/10566/21034 | |
| dc.language.iso | en | |
| dc.publisher | University of the Western Cape | |
| dc.subject | Hı Global Spectral Profile | |
| dc.subject | Asymmetries | |
| dc.subject | Deficiencies | |
| dc.subject | Galaxy Environment | |
| dc.subject | Cluster Environments | |
| dc.title | Hı asymmetries and deficiencies in Alfalfa galaxies | |
| dc.type | Thesis |