https://www.um.edu.mt/library/oar/handle/123456789/2065 Sun, 26 Apr 2026 01:05:41 GMT 2026-04-26T01:05:41Z https://www.um.edu.mt/library/oar/handle/123456789/145823 Title: EPOCHS VI : the size and shape evolution of galaxies since z ∼8 with JWST observations Authors: Ormerod, Katherine; Conselice, Christopher J.; Adams, Nathan J.; Harvey, Thomas A.; Austin, Duncan; Trussler, James A.A.; Ferreira, Leonardo De Albernaz; Caruana, Joseph; Lucatelli, Geferson; Li, Qiong; Roper, William J. Abstract: We present the results of a size and structural analysis of 1395 galaxies at 0.5 ≤ z ≲ 8 with stellar masses log (M*/M⊙)> 9.5 within the James Webb Space Telescope Public CEERS field that overlaps with the Hubble Space Telescope Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey EGS observations. We use GALFIT to fit single Sérsic models to the rest-frame optical profile of our galaxies, which is a mass-selected sample complete to our redshift and mass limit. Our primary result is that at fixed rest-frame wavelength and stellar mass, galaxies get progressively smaller, evolving as ∼(1 + z)−0.71 ± 0.19 up to z ∼ 8. We discover that the vast majority of massive galaxies at high redshifts have low Sérsic indices, thus do not contain steep, concentrated light profiles. Additionally, we explore the evolution of the size–stellar mass relationship, finding a correlation such that more massive systems are larger up to z ∼ 3. This relationship breaks down at z > 3, where we find that galaxies are of similar sizes, regardless of their star formation rates and Sérsic index, varying little with mass. We show that galaxies are more compact at redder wavelengths, independent of sSFR or stellar mass up to z ∼ 3. We demonstrate the size evolution of galaxies continues up to z ∼ 8, showing that the process or causes for this evolution is active at early times. We discuss these results in terms of ideas behind galaxy formation and evolution at early epochs, such as their importance in tracing processes driving size evolution, including minor mergers and active galactic nuclei activity. Mon, 01 Jan 2024 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/145823 2024-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/142655 Title: The interplay between accretion, downsizing, and the formation of box/peanut bulges in TNG50 Authors: Anderson, Stuart Robert; Gough-Kelly, Steven; Debattista, Victor P.; Du, Min; Erwin, Peter; Cuomo, Virginia; Caruana, Joseph; Hernquist, Lars; Vogelsberger, Mark Abstract: From the TNG50 cosmological simulation we build a sample of 191 well-resolved barred galaxies with stellar mass log(M/M) > 10 at z = 0. We search for box/peanut bulges (BPs) in this sample, finding them in 55 per cent of cases. We compute fBP, the BP probability for barred galaxies as a function of M, and find that this rises to a plateau, as found in observations of nearby galaxies. The transition mass where fBP reaches half the plateau value is log(M/M) = 10.13 ± 0.07, consistent with the observational value within measurement errors. We show that this transition in fBP can be attributed to the youth of the bars at low M, which is a consequence of downsizing. Young bars, being generally shorter and weaker, have not yet had time to form BPs. At high mass, while we find a plateau, the value is at ∼ 60 per cent whereas observations saturate at 100 per cent. We attribute this difference to excessive heating in TNG50 due to merger activity and numerical resolution effects. BPs in TNG50 tend to occur in galaxies with more quiescent merger histories. As a result, the main driver of whether a bar hosts a BP in TNG50 is not the galaxy mass, but how long and strong the bar is. Separating the BP sample into those that have visibly buckled and those that have not, we find that fully half of BP galaxies show clear signs of buckling, despite the excessive heating and limited vertical resolution of TNG50. Mon, 01 Jan 2024 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/142655 2024-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/140906 Title: Of comets and cosmology in Antonino Saliba's Nuova Figura di tutte le cose of 1582 Authors: Caruana, Joseph Abstract: Antonino Saliba, a sixteenth century cartographer hailing from the Maltese island of Gozo, published a map in 1582 espousing his cosmology. Its popularity at the time is attested via the multiple editions and copies that were produced in Europe. Numerous sky phenomena, amongst them comets, are portrayed in the map. This study presents a detailed analysis of Saliba’s treatment of these phenomena, following the first comprehensive translation of the map’s text to English. It elucidates the sources that Saliba used, clarifying and shedding further light on the views he held. Where possible, the comets mentioned by Saliba are identified and explained. Besides showing how Saliba wholly conformed to the Aristotelian and Ptolemaic representation of the world, in which respect he was quite orthodox, it is also shown for the first time that his work is significantly derived from previous and contemporary sources. Thu, 01 Jan 2026 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/140906 2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/138997 Title: Computational assessment of the deposited power and the temperature increase around two coupled implanted leads inside a 1.5 T MRI scanner Authors: Tsanidis, George; Samaras, Theodoros Abstract: A specific method for the estimation of the induced power at the tip by an active implantable medical device (AIMD) during an MRI scan is not defined in ISO/TS 10974:2018 for the cases of devices with multiple leads or the presence of abandoned and retained leads, where coupling between two leads could take place. Therefore, the aim of this work is to evaluate a numerical method, similar to Tier 3 of ISO/TS 10974:2018, for the estimation of the deposited power at the tips of two coupled implanted leads. Specifically, the proposed methodology applies the same parameters as the standard Tier 3 process. However, these parameters are calculated for each implant in the presence of its neighbors in order to include the coupling between them. Numerical electromagnetic simulations were performed, in which a pair of generic implant leads was excited and placed at various positions relative to each other. The deposited power at the tips of the pair was analyzed based on the standard Tier 3 approach, and the results show that this could overestimate the induced power by more than 6 dB. Therefore, a modified Tier 3 numerical method for the estimation of the deposited power at their tips is proposed, which can produce a reliable calculation. This method was confirmed by evaluating various configurations of the two leads excited by orthogonal electrical fields, and also its uncertainty budget was developed. Finally, the method was repeated for different properties of the generic implants and the surrounding tissue, as well as for a pair of realistic implants and in vivo implantation trajectories. Mon, 01 Jan 2024 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/138997 2024-01-01T00:00:00Z