https://www.um.edu.mt/library/oar/handle/123456789/16096 2026-06-14T01:41:35Z https://www.um.edu.mt/library/oar/handle/123456789/147380 Title: The breakthrough listen search for intelligent life : a laser search pipeline for the automated planet finder Authors: Zuckerman, Anna; Ko, Zoe; Isaacson, Howard; Croft, Steve; Price, Danny; Lebofsky, Matt; Siemion, Andrew P. V. Abstract: The Search for Extraterrestrial Intelligence has traditionally been conducted at radio wavelengths, but optical searches are well-motivated and increasingly feasible due to the growing availability of high-resolution spectroscopy. We present a data analysis pipeline to search Automated Planet Finder (APF) spectroscopic observations from the Levy Spectrometer for intense, persistent, narrow-bandwidth optical lasers. We describe the processing of the spectra, the laser search algorithm, and the results of our laser search on 1983 spectra of 388 stars as part of the Breakthrough Listen search for technosignatures. We utilize an empirical spectra-matching algorithm called SpecMatch-Emp to produce residuals between each target spectrum and a set of best-matching catalog spectra, which provides the basis for a more sensitive search than previously possible. We verify that SpecMatch-Emp performs well on APF-Levy spectra by calibrating the stellar properties derived by the algorithm against the SpecMatch-Emp library and against Gaia catalog values. We leverage our unique observing strategy, which produces multiple spectra of each target per night of observing, to increase our detection sensitivity by programmatically rejecting events that do not persist between observations. With our laser search algorithm, we achieve a sensitivity equivalent to the ability to detect an 84 kW laser at the median distance of a star in our data set (78.5 ly). We present the methodology and vetting of our laser search, finding no convincing candidates consistent with potential laser emission in our target sample. 2023-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/147372 Title: Characterization of the repeating FRB 20220912A with the Allen telescope array Authors: Sheikh, Sofia Z.; Farah, Wael; Pollak, Alexander W.; Siemion, Andrew P. V.; Chamma, Mohammed A.; Cruz, Luigi F.; Davis, Roy H.; DeBoer, David R.; Gajjar, Vishal; Karn, Phil; Kittling, Jamar; Lu, Wenbin; Masters, Mark; Premnath, Pranav; Schoultz, Sarah; Shumaker, Carol; Singh, Gurmehar; Snodgrass, Michael Abstract: FRB 20220912A is a repeating Fast Radio Burst (FRB) that was discovered in Fall 2022 and remained highly active for several months. We report the detection of 35 FRBs from 541 h of follow-up observations of this source using the recently refurbished Allen Telescope Array, covering 1344 MHz of bandwidth primarily centred at 1572 MHz. All 35 FRBs were detected in the lower half of the band with non-detections in the upper half and covered fluences from 4–431 Jy-ms (median = 48.27 Jy-ms). We find consistency with previous repeater studies for a range of spectrotemporal features including: bursts with downward frequency drifting over time; a positive correlation between bandwidth and centre frequency; and a decrease in sub-burst duration over time. We report an apparent decrease in the centre frequency of observed bursts over the two months of the observing campaign (corresponding to a drop of 6.21 ± 0.76 MHz per d). We predict a cut-off fluence for FRB 20220912A of Fmax ≲ 104 Jy-ms, for this source to be consistent with the all-sky rate, and find that FRB 20220912A significantly contributed to the all-sky FRB rate at a level of a few per cent for fluences of ∼100 Jy-ms. Finally, we investigate characteristic time-scales and sub-burst periodicities and find (a) a median inter-subburst time-scale of 5.82 ± 1.16 ms in the multi-component bursts and (b) no evidence of strict periodicity even in the most evenly spaced multi-component burst in the sample. Our results demonstrate the importance of wideband observations of FRBs, and provide an important set of observational parameters against which to compare FRB progenitor and emission mechanism models. 2024-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/147367 Title: First light and reionization epoch simulations (FLARES) IX : the physical mechanisms driving compact galaxy formation and evolution Authors: Roper, William J.; Lovell, Christopher C.; Vijayan, Aswin P.; Irodotou, Dimitrios; Kuusisto, Jussi K.; Matharu, Jasleen; Seeyave, Louise T. C.; Thomas, Peter A.; Wilkins, Stephen M. Abstract: In the First Light And Reionization Epoch Simulations (Flares) suite of hydrodynamical simulations, we find the high-redshift (z > 5) intrinsic size–luminosity relation is, surprisingly, negatively sloped. However, after including the effects of dust attenuation, we find a positively sloped UV observed size–luminosity relation in good agreement with other simulated and observational studies. In this work, we extend this analysis to probe the underlying physical mechanisms driving the formation and evolution of the compact galaxies driving the negative size–mass/size–luminosity relation. We find the majority of compact galaxies (R1/2, ⋆ < 1 pkpc, which drive the negative slope of the size–mass relation, have transitioned from extended to compact sizes via efficient centralized cooling, resulting in high specific star formation rates in their cores. These compact stellar systems are enshrouded by non-star-forming gas distributions as much as 100 times larger than their stellar counterparts. By comparing with galaxies from the Eagle simulation suite, we find that these extended gas distributions ‘turn on’ and begin to form stars between z = 5 and 0 leading to increasing sizes, and thus the evolution of the size–mass relation from a negative to a positive slope. This explicitly demonstrates the process of inside-out galaxy formation in which compact bulges form earlier than the surrounding discs. 2023-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/147149 Title: COSMOS-web : an overview of the JWST cosmic origins survey Authors: Casey, Caitlin M.; Kartaltepe, Jeyhan S.; Drakos, Nicole E.; Franco, Maximilien; Harish, Santosh; Paquereau, Louise; Ilbert, Olivier; Rose, Caitlin; Cox, Isabella G.; Nightingale, James W.; Robertson, Brant E.; Silverman, John D.; Koekemoer, Anton M.; Massey, Richard; McCracken, Henry Joy; Rhodes, Jason; Akins, Hollis B.; Allen, Natallie; Amvrosiadis, Aristeidis; Arango-Toro, Rafael C.; Bagley, Micaela B.; Bongiorno, Angela; Capak, Peter L.; Champagne, Jaclyn B.; Chartab, Nima; Chávez Ortiz, Óscar A.; Chworowsky, Katherine; Cooke, Kevin C.; Cooper, Olivia R.; Darvish, Behnam; Ding, Xuheng; Faisst, Andreas L.; Finkelstein, Steven L.; Fujimoto, Seiji; Gentile, Fabrizio; Gillman, Steven; Gould, Katriona M. L.; Gozaliasl, Ghassem; Hayward, Christopher C.; He, Qiuhan; Hemmati, Shoubaneh; Hirschmann, Michaela; Jahnke, Knud; Jin, Shuowen; Khostovan, Ali Ahmad; Kokorev, Vasily; Lambrides, Erini; Laigle, Clotilde; Larson, Rebecca L.; Leung, Gene C. K.; Liu, Daizhong; Liaudat, Tobias; Long, Arianna S.; Magdis, Georgios; Mahler, Guillaume; Mainieri, Vincenzo; Manning, Sinclaire M.; Maraston, Claudia; Martin, Crystal L.; McCleary, Jacqueline E.; McKinney, Jed; McPartland, Conor J. R.; Mobasher, Bahram; Pattnaik, Rohan; Renzini, Alvio; Rich, R. Michael; Sanders, David B.; Sattari, Zahra; Scognamiglio, Diana; Scoville, Nick; Sheth, Kartik; Shuntov, Marko; Sparre, Martin; Suzuki, Tomoko L.; Talia, Margherita; Toft, Sune; Trakhtenbrot, Benny; Urry, C. Megan; Valentino, Francesco; Vanderhoof, Brittany N.; Vardoulaki, Eleni; Weaver, John R.; Whitaker, Katherine E.; Wilkins, Stephen M.; Yang, Lilan; Zavala, Jorge A. Abstract: We present the survey design, implementation, and outlook for COSMOS-Web, a 255 hr treasury program conducted by the James Webb Space Telescope in its first cycle of observations. COSMOS-Web is a contiguous 0.54 deg2 NIRCam imaging survey in four filters (F115W, F150W, F277W, and F444W) that will reach 5σ point-source depths ranging ∼27.5–28.2 mag. In parallel, we will obtain 0.19 deg2 of MIRI imaging in one filter (F770W) reaching 5σ point-source depths of ∼25.3–26.0 mag. COSMOS-Web will build on the rich heritage of multiwavelength observations and data products available in the COSMOS field. The design of COSMOS-Web is motivated by three primary science goals: (1) to discover thousands of galaxies in the Epoch of Reionization (6 ≲ z ≲ 11) and map reionization’s spatial distribution, environments, and drivers on scales sufficiently large to mitigate cosmic variance, (2) to identify hundreds of rare quiescent galaxies at z > 4 and place constraints on the formation of the universe’s most-massive galaxies (M⋆ > 1010M⊙), and (3) directly measure the evolution of the stellar-mass-to-halo-mass relation using weak gravitational lensing out to z ∼ 2.5 and measure its variance with galaxies’ star formation histories and morphologies. In addition, we anticipate COSMOS-Web’s legacy value to reach far beyond these scientific goals, touching many other areas of astrophysics, such as the identification of the first direct collapse black hole candidates, ultracool subdwarf stars in the Galactic halo, and possibly the identification of z > 10 pair-instability supernovae. In this paper we provide an overview of the survey’s key measurements, specifications, goals, and prospects for new discovery. 2023-01-01T00:00:00Z