https://www.um.edu.mt/library/oar/handle/123456789/16096 Thu, 27 Aug 2026 03:57:45 GMT 2026-08-27T03:57:45Z https://www.um.edu.mt/library/oar/handle/123456789/148646 Title: A VERITAS/breakthrough listen search for optical technosignatures Authors: Acharyya, Atreya; Adams, Colin; Archer, A.; Bangale, Priyadarshini; Batista, Pedro; Benbow, Wystan; Brill, Aryeh; Capasso, Massimo; Errando, Manel; Falcone, Abraham; Feng, Qi; Finley, J. P.; Foote, Juniper; Fortson, Lucy; Furniss, Amy; Griffin, S.; Hanlon, William; Hanna, David; Hervet, Olivier; Hinrichs, Claire; Hoang, J.; Holder, Jamie; Humensky, Thomas; Jin, Weidong; Kaaret, Philip; Kertzman, M.; Kherlakian, M.; Kieda, David; Kleiner, Tobias K.; Korzoun, Nikolas; Kumar, Sajan; Lang, M.J.; Lundy, Matthew; Maier, Gernot; McGrath, C. E.; Millard, Matthew; Miller, H. R.; Millis, J.; Mooney, Connor; Moriarty, Patrick; Mukherjee, Reshmi; O’Brien, Stephan; Ong, Rene; Pohl, Martin; Pueschel, Elisa; Quinn, John; Ragan, Ken; Reynolds, P. T.; Ribeiro, Deivid; Roache, E.; Ryan, James; Sadeh, Iftach; Saha, Lab; Santander, Marcos; Sembroski, G. H.; Shang, Ruo-Yu; Tak, D.; Talluri, A. K.; Tucci, J. V.; Vazquez, N.; Williams, David A.; Wong, Samantha; Woo, Jooyun; DeBoer, David; Isaacson, Howard; de Pater, I.; Price, D. C.; Siemion, Andrew P. V. Abstract: The Breakthrough Listen Initiative is conducting a program using multiple telescopes around the world to search for “technosignatures”: artificial transmitters of extraterrestrial origin from beyond our solar system. The Very Energetic Radiation Imaging Telescope Array System (VERITAS) Collaboration joined this program in 2018 and provides the capability to search for one particular technosignature: optical pulses of a few nanoseconds in duration detectable over interstellar distances. We report here on the analysis and results of dedicated VERITAS observations of Breakthrough Listen targets conducted in 2019 and 2020 and of archival VERITAS data collected since 2012. Thirty hours of dedicated observations of 136 targets and 249 archival observations of 140 targets were analyzed and did not reveal any signals consistent with a technosignature. The results are used to place limits on the fraction of stars hosting transmitting civilizations. We also discuss the minimum pulse sensitivity of our observations and present VERITAS observations of CALIOP: a space-based pulsed laser on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations. The detection of these pulses with VERITAS, using the analysis techniques developed for our technosignature search, allows a test of our analysis efficiency and serves as an important proof of principle. Sun, 01 Jan 2023 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/148646 2023-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/148536 Title: The breakthrough listen search for intelligent life : detection and characterization of anomalous transits in Kepler lightcurves Authors: Zuckerman, Anna; Davenport, James R. A.; Croft, Steve; Siemion, Andrew P. V.; de Pater, Imke Abstract: Never before has the detection and characterization of exoplanets via transit photometry been as promising and feasible as it is now, due to the increasing breadth and sensitivity of time domain optical surveys. Past works have made use of phase-folded stellar lightcurves in order to study the properties of exoplanet transits because this provides the highest signal that a transit is present at a given period and ephemeris. Characterizing transits on an individual, rather than phase-folded, basis is much more challenging due to the often low signal-to-noise ratio of lightcurves, missing data, and low sampling rates. However, by phase folding a lightcurve we implicitly assume that all transits have the same expected properties, and lose all information about the nature and variability of the transits. We miss the natural variability in transit shapes, or even the deliberate or inadvertent modification of transit signals by an extraterrestrial civilization (for example, via laser emission or orbiting megastructures). In this work, we develop an algorithm to search stellar lightcurves for individual anomalous (in timing or depth) transits, and we report the results of that search for 218 confirmed transiting exoplanet systems from Kepler. Mon, 01 Jan 2024 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/148536 2024-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/148383 Title: A z = 1.85 galaxy group in CEERS : evolved, dustless, massive intra-halo light and a brightest group galaxy in the making Authors: Coogan, Rosemary T.; Daddi, Emanuele; Le Bail, Aurélien; Elbaz, David; Dickinson, Mark; Giavalisco, Mauro; Gómez-Guijarro, Carlos; de la Vega, Alexander; Bagley, Micaela; Finkelstein, Steven L.; Franco, Maximilien; Cooray, Asantha R.; Behroozi, Peter; Bisigello, Laura; Casey, Caitlin M.; Ciesla, Laure; Dimauro, Paola; Finoguenov, Alexis; Koekemoer, Anton M.; Lucas, Ray A.; Pérez-González, Pablo G.; Yung, L. Y. Aaron; Arrabal Haro, Pablo; Kartaltepe, Jeyhan S.; Jogee, Shardha; Papovich, Casey; Pirzkal, Nor; Wilkins, Stephen M. Abstract: We present CEERS JWST/NIRCam imaging of a massive galaxy group at z = 1.85, to explore the early JWST view on massive group formation in the distant Universe. The group contains ≳16 members (including six spectroscopic confirmations) down to log10(M⋆/M⊙) = 8.5, including the brightest group galaxy (BGG) in the process of actively assembling at this redshift. The BGG is comprised of multiple merging components extending ∼3.6″ (30 kpc) across the sky. The BGG contributes 69% of the group’s total galactic stellar mass, with one of the merging components containing 76% of the total mass of the BGG and a star formation rate > 1810 M⊙ yr−1. Most importantly, we detected intra-halo light (IHL) in several HST and JWST/NIRCam bands, allowing us to construct a state-of-the-art rest-frame UV-NIR spectral energy distribution of the IHL for the first time at this high redshift. This allows stellar population characterisation of both the IHL and member galaxies, as well as the morphology distribution of group galaxies versus their star formation activity when coupled with Herschel data. We created a stacked image of the IHL, giving us a sensitivity to extended emission of 28.5 mag arcsec−2 at rest-frame 1 μm. We find that the IHL is extremely dust poor (Av ∼ 0), containing an evolved stellar population of log10(t50/yr) = 8.8, corresponding to a formation epoch for 50% of the stellar material 0.63 Gyr before z = 1.85. There is no evidence of ongoing star formation in the IHL. The IHL in this group at z = 1.85 contributes ∼10% of the total stellar mass, comparable with what is observed in local clusters. This suggests that the evolution of the IHL fraction is more self-similar with redshift than predicted by some models, challenging our understanding of IHL formation during the assembly of high-redshift clusters. JWST is unveiling a new side of group formation at this redshift, which will evolve into Virgo-like structures in the local Universe. Thu, 01 Jan 2026 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/148383 2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/147572 Title: A Green Bank Telescope search for narrowband technosignatures between 1.1 and 1.9 GHz during 12 Kepler planetary transits Authors: Sheikh, Sofia Z.; Kanodia, Shubham; Lubar, Emily; Bowman, William P.; Cañas, Caleb I.; Gilbertson, Christian; MacDonald, Mariah G.; Wright, Jason; MacMahon, David; Croft, Steve; Price, Danny; Siemion, Andrew P. V.; Drew, Jamie; Worden, S. Pete; Trenholm, Elizabeth Abstract: Agrowing avenue for determining the prevalence of life beyond Earth is to search for “technosignatures” from extraterrestrial intelligences/agents. Technosignatures require significant energy to be visible across interstellar space and thus intentional signals might be concentrated in frequency, in time, or in space, to be found in mutually obvious places. Therefore, it could be advantageous to search for technosignatures in parts of parameter space that are mutually derivable to an observer on Earth and a distant transmitter. In this work, we used the L-band (1.1–1.9 GHz) receiver on the Robert C. Byrd Green Bank Telescope to perform the first technosignature search presynchronized with exoplanet transits, covering 12 Kepler systems. We used the Breakthrough Listen turboSETI pipeline to flag narrowband hits (∼3 Hz) using a maximum drift rate of ±614.4 Hz s−1 and a signal-to-noise threshold of 5—the pipeline returned ∼3.4 × 105 apparently-localized features. Visual inspection by a team of citizen scientists ruled out 99.6% of them. Further analysis found two signals of interest that warrant follow up, but no technosignatures. If the signals of interest are not redetected in future work, it will imply that the 12 targets in the search are not producing transit-aligned signals from 1.1 to 1.9 GHz with transmitter powers >60 times that of the former Arecibo radar. This search debuts a range of innovative technosignature techniques: citizen science vetting of potential signals of interest, a sensitivity-aware search out to extremely high drift rates, a more flexible method of analyzing on-off cadences, and an extremely low signal-to-noise threshold. Sun, 01 Jan 2023 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/147572 2023-01-01T00:00:00Z