Seminar and Journal Club

Yuri Uno
April 25, 2024
Zoom recording

Abstract:
SETI (Search for Extraterrestrial Intelligence) efforts have primarily targeted stellar systems within our Galaxy, with the anticipation of discovering civilizations similar to our own (Type I as defined by the Kardashev scale). Despite six decades of persistent searching and launching over a hundred SETI projects, we have yet to achieve success. A potential reason could be the sheer vastness of the parameter space we need to explore. Or it might be time to reconsider our approach. If civilizations more advanced than ours do exist, as proposed by Nikolai Kardashev, their technosignatures could potentially be detectable with our current telescopes, even from distant galaxies. We are eager to delve into this uncharted territory: Extragalactic SETI. To start with, we have reanalyzed the Breakthrough Listen (BL) data to see how many galaxies the BL could have observed when we shift our focus from the stellar systems, the initial BL target, to the galaxies that happen to be within the beam of radio telescopes. As a result, we set the tightest upper limit on the transmitter rate: ~10^-13 within 969 Mpc above 7.7×10^26W of power, indicating civilizations transmitting powerful radio in high duty-cycle are quite few. In the presentation, I will discuss the latest endeavors of our team in the realm of extragalactic SETI.

Andy Nilipour
April 18, 2024
Zoom recording

Abstract:
Spatiotemporal techniques for signal coordination with actively transmitting extraterrestrial civilizations, without the need for prior communication, can constrain technosignature searches to a significantly smaller coordinate space. Techniques such as the SETI Ellipsoid have been discussed for decades, but more recent strategies, such as those proposed by Seto (2021) and Seto (2024), relax certain astrometrical requirements while retaining the underlying idea of synchronizing signals with conspicuous astrophysical events. These strategies can also give ways to new frameworks for technosignature analysis in the time domain using telescopes and surveys such as Gaia, TESS, and the upcoming Rubin Observatory. I will discuss signal synchronization strategies beyond just the SETI Ellipsoid, some recent developments in time domain SETI, and how the two can be combined in archival, and potentially real-time, data.

Winter Parts
April 4 & 11, 2024
Zoom recording (part 1, April 4, 2024)
Zoom recording (part 2, April 11, 2024)

Abstract:
Winter will present and discuss 3 papers on Solar System SETI. We will begin with a discussion of R. N. Bracewell’s 1960 paper on Solar System probes, along with a classic Solar System SETI paper from R. A. Freitas. We will then discuss a 2024 paper from B. Rogers et al. on Solar System anomaly searches with LSST and the connections of this search to SETI.

Daniel Giles
March 28, 2024
Zoom recording

Abstract:
In recent years, the search for life in the universe has diversified its parameter space well beyond the radio spectrum of classical SETI (Search for ExtraTerrestrial Intelligence) efforts. As part of our own SETI program, we have embarked on an archival research project to identify non-exoplanetary transiting bodies around stars observed by the TESS primary mission (2018-2020). In particular, we are interested in transiting “megastructures” — artificial objects that are large enough to cause detectable fading when passing through our line of sight to the host star. I will discuss our anomaly detection pipeline, how we have vetted identified anomalies, results of signal injection work, and remaining mysteries.

Frank Hirth
March 21, 2024
Zoom recording

Abstract:
Since its inception at the Green Bank meeting with Drake’s equation in 1961, the search for extra-terrestrial intelligence (SETI) has seen tangible progress in exploring our universe and outer space. However, 60+ years onwards, no sign of other life and intelligence has been found, resounding Fermi’s quip “Where is everybody?” This silence might be less a failure of using correct numbers and technology, than inherent to the quest what to look and listen for. Life as we know it is bound to first principles by which brains evolved in a historical process Darwin described in his theory, but the underlying mechanisms are far from being understood. We do know, however, that intelligence and communication are emergent traits of complex brains, one of which led to SETI. In this seminar, I will introduce first principles how brains evolved in animals and what they have in common; address the concepts of single vs. multiple origins of nerve cells that are the core units of the brain; describe the functional elements that are prerequisites of emergent traits like intelligence and communication; and illustrate their conduct in different species, ranging from bees and birds to mammals. I will conclude with a brief discussion of contingency and determinism by reference to Gould’s question whether replaying the tape of life would lead to similar outcomes like the human mind. These deliberations may illuminate the parameters f(l), f(i) and f(c) of Drake’s equation and their limitations that together can facilitate the Q&A session afterwards.

Rebecca Charbonneau
February 22, 2024
Zoom recording

Abstract:
Frank Drake’s Arecibo message is often credited as the first case of using a radio telescope to send a message to extraterrestrial intelligence (METI). But was it? In this talk, I will delve into historical records to examine possible attempts predating the Arecibo message, shedding light on the complexity of our early endeavors to reach out to potential extraterrestrial civilizations. I will also cover other lesser-known examples of METI in the 20th century and put into context some of the early controversy surrounding METI.

Peter Xiangyuan Ma
February 15, 2024
Zoom recording

Abstract:
Modern radio astronomy instruments generate vast amounts of data, and the increasingly challenging radio frequency interference (RFI) environment necessitates ever-more sophisticated RFI rejection algorithms. The ‘needle in a haystack’ nature of searches for transients and technosignatures requires us to develop methods that can determine whether a signal of interest has unique properties, or is a part of some larger set of pernicious RFI. To tackle this growing problem recent advances in deep learning has shown promise in aiding in our search efforts. In this talk we discuss the development of deep learning techniques for a “forward” search to discover anomalous candidates and as well as a “backward/reverse” search to then verify anomalous candidates once they have been flagged. We aim to introduce a more comprehensive pipeline to automate signal discovery and verification.

Sofia Sheikh
February 8, 2024
Zoom recording

Abstract:
The Allen Telescope Array (ATA) is a 42-dish radio interferometer located in Hat Creek, California and operated by the SETI Institute. The ATA is in the process of being upgraded with new feeds and improved backends, which should be completed on all 42 antennas by the end of 2024. In the meantime, the instrument is being used in a 20-element mode for a host of Search for Extraterrestrial Intelligence (SETI) programs, in keeping with the spirit of its original technosignature-focused design. In this talk, I will review the current state of the array and its future capabilities with regards to technosignature searches, and give an overview of four exciting SETI programs on the new instrument: a nearby star survey, an anti-solar point search, a planet-planet occultation observation, and a SETI ellipsoid campaign. I will also briefly mention the transformative non-SETI science being produced by the ATA, e.g., Fast Radio Burst (FRB) characterization and slow transient science.

Owen Johnson
February 1, 2024
Zoom recording

Abstract:
The Search for Extraterrestrial Intelligence aims to find evidence of technosignatures, which can point toward the possible existence of technologically advanced extraterrestrial life. Radio signals similar to those engineered on Earth may be transmitted by other civilizations, motivating technosignature searches across the entire radio spectrum. In this endeavor, the low-frequency radio band has remained largely unexplored; with prior radio searches primarily above 1 GHz. In this presentation we discuss the results of a recent low-frequency survey of over 1,600,000 stars in our Galaxy with LOFAR (110 – 190 MHz), the expansion of SETI searches to NenuFAR (10 – 85 MHz) and the future observation plans for technosignatures at low frequencies.

Benji Fields
January 25, 2024
Zoom recording

Abstract:
I outline an archival search for lasers from 2,821 stars, and an active followup investigation into the most interesting technosignature candidate we’ve found. After searching for statistically significant narrow emission spikes, we subjected each detection to a series of tests for false positives, including cosmic rays, bleedthrough from the Th-Ar calibration lamp, night sky airglow lines, and large clusters of emission lines indicative of natural stellar activity. Of the 294 initial detections, 29.3% appear to be natural emission lines, 47.6 % showed visual signatures of cosmic rays and 2.4% were due to calibration lamp bleedthrough. From the remaining 17.7% of candidate observations, we eliminated spikes with linewidths narrower than the instrumental PSF as being the likely product of cosmic rays or other non optical phenomena. This left 14 candidates which survived all filters. Of these 14, a majority are ambiguous–but one in particular matches many of the physical characteristics one would expect from an extraterrestrial laser. The candidate did not repeat in any subsequent observations. It also originates from a G0V type star–not generally known for emission line producing activity. I will share the cosmic detective story emerging around this candidate, and alternative/prosaic hypotheses which we’ve examined. These include interference from LiDAR satellites and drones, natural stellar activity, atmospheric phenomena, ground based adaptive optics lasers, as well as outside contamination from a variety of human light sources including LED and Halogen lights. I will also show the results of an optimal extraction test using the PyReduce algorithm, and what it reveals about the candidate. I will outline a future research program which will assess both the candidate’s viability as a technosignature, as well as any natural astrophysical explanations which may emerge in the process. Finally, I will use this as an opportunity to share my own epistemological framework for non-repeating “Wow! Signal”-type candidates: where they may fit into SETI as whole, and an investigative strategy to uncover their origin.