Environment has long been known to have significant impact on the evolutionof galaxies, but here we seek to quantify the subtler differences that might befound in disk galaxies, depending on whether they are isolated, the mostmassive galaxy in a group (centrals), or a lesser member (satellites). TheMaNGA survey allows us to define a large mass-matched sample of 574 galaxieswith high-quality integrated spectra in each category. Initial examination oftheir spectral indices indicates significant differences, particularly inlow-mass galaxies. Semi-analytic spectral fitting of a full chemical evolutionmodel to these spectra confirms these differences, with low-mass satelliteshaving a shorter period of star formation and chemical enrichment typical of aclosed box, while central galaxies have more extended histories, with evidenceof on-going gas accretion over their lifetimes. The derived parameters for gasinfall timescale and wind strength suggest that low-mass satellite galaxieshave their hot halos of gas effectively removed, while central galaxies retaina larger fraction of gas than isolated galaxies due to the deeper grouppotential well in which they sit. S0 galaxies form a distinct subset within thesample, particularly at higher masses, but do not bias the inferred lower-massenvironmental impact significantly. The consistent picture that emergesunderlines the wealth of archaeological information that can be extracted fromhigh-quality spectral data using techniques like semi-analytic spectralfitting.

We conduct hydrodynamical cosmological zoom simulations of fourteen voids tostudy the ability of haloes to accrete gas at different locations throughoutthe voids at z = 0. Measuring the relative velocity of haloes with respect totheir ambient gas, we find that a tenth of the haloes are expected to be unableto accrete external gas due to its fast flow passed them (so called 'fast flowhaloes'). These are typically located near void walls. We determine that thesehaloes have recently crossed the void wall and are still moving away from it.their motion counter to that of ambient gas falling towards the void wallresults in fast flows that make external gas accretion very challenging, andoften cause partial gas loss via the resultant ram pressures. Using ananalytical approach, we model the impact of such ram pressures on the gasinside haloes of different masses. A halo's external gas accretion is typicallycut off, with partial stripping of halo gas. For masses below a few times10$^{9}$ M$_{\odot}$, their halo gas is heavily truncated but not completelystripped. We identify numerous examples of haloes with a clear jelly-fish likegas morphology, indicating their surrounding gas is being swept away, cuttingthem off from further external accretion. These results highlight how, even inthe relatively low densities of void walls, a fraction of galaxies can interactwith large-scale flows in a manner that has consequences for their gas contentand ability to accrete gas.

Understanding the formation and evolution of ring galaxies, galaxies with anatypical ring-like structure, will improve understanding of black holes andgalaxy dynamics as a whole. Current catalogs of rings are extremely limited:manual analysis takes months to accumulate an appreciable sample of rings andexisting computational methods are vastly limited in terms of accuracy anddetection rate. Without a sizable sample of rings, further research into theirproperties is severely restricted. This project investigates the usage of aconvolutional neural network (CNN) to identify rings from unclassified samplesof galaxies. A CNN was trained on a sample of 100,000 simulated galaxies,transfer learned to a sample of real galaxies and applied to a previouslyunclassified dataset to generate a catalog of rings which was then manuallyverified. Data augmentation with a generative adversarial network (GAN) tosimulate images of galaxies was also used. A catalog of 1151 rings wasextracted with 7.4 times the precision and 15.4 times the detection rate ofconventional algorithms. The properties of these galaxies were then estimatedfrom their photometry and compared to the Galaxy Zoo 2 catalog of rings. Withupcoming surveys such as the Vera Rubin Observatory Legacy Survey of Space andTime obtaining images of billions of galaxies, similar models could be crucialin classifying large populations of rings to better understand the peculiarmechanisms by which they form and evolve.