Searching for Broadband Pulsed Beacons from 1883 Stars Using Neural Networks

Gajjar, Vishal; LeDuc, Dominic; Chen, Jiani; Siemion, Andrew; Sheikh, Sofia; Brzycki, Bryan; Croft, Steve; Czech, Daniel; DeBoer, David R.; DeMarines, Julia; Drew, Jamie; Isaacson, Howard; Lacki, Brian C.; Lebofsky, Matt; MacMahon, David H. E.; Ng, Cherry; Pater, Imke de; Perez, Karen I.; Price, Danny C.; Suresh, Akshay; Webb, Claire; Worden, Simon P.

doi:10.3847/1538-4357/ac6dd5

Cited by 9 publications

(7 citation statements)

References 44 publications

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“…Our FFA searches bring novelty to radio SETI through their targeting of periodic spectral signals, a historically underexplored class of potential extraterrestrial transmissions. In contrast, traditional radio SETI programs have generally focused on the discovery of Doppler-drifting Hz-wide CW beacons (Siemion et al 2013;Harp et al 2016;Tingay et al 2016;Enriquez et al 2017;Gray & Mooley 2017;Margot et al 2018Margot et al , 2021Pinchuk et al 2019;Price et al 2020;Gajjar et al 2021;Lacki et al 2021;Traas et al 2021;Franz et al 2022;Garrett & Siemion 2023;Tusay et al 2022) and artificially dispersed broadband bursts (Gajjar et al 2021(Gajjar et al , 2022. Consequently, an equal comparison of our search sensitivity against that of past radio SETI campaigns is difficult.…”

Section: Comparisons With Past Surveysmentioning

confidence: 97%

“…Notably, our algorithm is agnostic to any radio frequency drifts exhibited in the dynamic spectrum. Therefore, blipss can enable discovery of periodic pulsed beacons with exotic swept frequency structures that are frequently missed by traditional broadband pulse search techniques assuming cold plasma dispersion (e.g., Lazarus et al 2015;Gajjar et al 2021Gajjar et al , 2022.…”

Section: Test Pulsar Detectionmentioning

confidence: 99%

“…Allowing for both natural and artificial dispersion, Gajjar et al (2022) conducted extensive searches for broadband pulsed beacons from 1883 stars in the Milky Way. Their investigations reveal that 1 in 1000 stars transmit pulses repeating 500 s with equivalent isotropic radiated power (EIRP)  10 22 W at 4-8 GHz.…”

Section: Introductionmentioning

confidence: 99%

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A 4–8 GHz Galactic Center Search for Periodic Technosignatures

Suresh

Gajjar

Nagarajan

et al. 2023

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Radio searches for extraterrestrial intelligence have mainly targeted the discovery of narrowband continuous-wave beacons and artificially dispersed broadband bursts. Periodic pulse trains, in comparison to the above technosignature morphologies, offer an energetically efficient means of interstellar transmission. A rotating beacon at the Galactic Center (GC), in particular, would be highly advantageous for galaxy-wide communications. Here, we present blipss, a CPU-based open-source software that uses a fast folding algorithm (FFA) to uncover channel-wide periodic signals in radio dynamic spectra. Running blipss on 4.5 hr of 4–8 GHz data gathered with the Robert C. Byrd Green Bank Telescope, we searched the central 6 ′ of our galaxy for kHz-wide signals with periods between 11 and 100 s and duty cycles (δ) between 10% and 50%. Our searches, to our knowledge, constitute the first FFA exploration for periodic alien technosignatures. We report a nondetection of channel-wide periodic signals in our data. Thus, we constrain the abundance of 4–8 GHz extraterrestrial transmitters of kHz-wide periodic pulsed signals to fewer than one in about 600,000 stars at the GC above a 7σ equivalent isotropic radiated power of ≈2 × 1018 W at δ ≃ 10%. From an astrophysics standpoint, blipss, with its utilization of a per-channel FFA, can enable the discovery of signals with exotic radio frequency sweeps departing from the standard cold plasma dispersion law.

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Section: Comparisons With Past Surveysmentioning

confidence: 97%

Section: Test Pulsar Detectionmentioning

confidence: 99%

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A 4–8 GHz Galactic Center Search for Periodic Technosignatures

Suresh

Gajjar

Nagarajan

et al. 2023

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“…Despite over 60 yr of activity, it is thus not surprising that the search for extraterrestrial intelligence, or more properly the search for remotely detectable manifestations of technology (also known as technosignatures), has so far ended up emptyhanded. The strategy behind SETI's ongoing efforts, then, is to continually improve the sampled search space through increasingly comprehensive surveys, such as the Breakthrough Listen initiative (Worden et al 2017), or to consider technosignatures more exotic than radio or optical (Sellers et al 2022) with the hope of eventually finding the long-sought needle in the cosmic haystack, or at least placing even tighter upper limits on its existence (Enriquez et al 2017;Grimaldi & Marcy 2018;Price et al 2020;Wlodarczyk-Sroka et al 2020;Gajjar et al 2021Gajjar et al , 2022Suazo et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Inferring the Rate of Technosignatures from 60 yr of Nondetection

Grimaldi

2023

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For about the last 60 yr the search for extraterrestrial intelligence has been monitoring the sky for evidence of remotely detectable technological life beyond Earth, with no positive results to date. While the lack of detection can be attributed to the highly incomplete sampling of the search space, technological emissions may be actually rare enough that we are living in a time when none cross the Earth. Here we explore the latter possibility and derive the likelihood of the Earth not being crossed by signals for at least the last 60 yr to infer upper bounds on their rate of emission. Under the assumption that technological emitters are distributed uniformly in the Milky Way and that they generate technoemissions at a constant rate, we find less than about one to five emissions generated per century with 95% credible level. This implies optimistic waiting times until the next crossing event of no less than 60–1800 yr with a 50% probability. A significant fraction of highly directional signals increases the emission rates’ upper bounds, but without systematically changing the waiting time. Although these probabilistic bounds are derived from a specific model and their validity depends on the model’s assumptions, they are nevertheless quite robust against weak time dependences of the emission rate or nonuniform spatial distributions of the emitters. Our results provide therefore a benchmark for assessing the lack of detection and may serve as a basis to form optimal strategies for the search for extraterrestrial intelligence.

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“…Since the launch of the Breakthrough Initiatives, 14 in particular Breakthrough Listen in 2015 (Isaacson et al 2017;Worden et al 2017), dedicated observations with the Parkes 64 m telescope (Murriyang) and the GBT have yielded improved sensitivities (approximately an order of magnitude over Project Phoenix) but on a similar order of 1000-2000 stars (i.e., Enriquez et al 2017;Price et al 2020;Gajjar et al 2022;Ma et al 2023). These programs were also initially limited in frequency coverage; however, in the last 3 yr, the search has broadened to cover the range of ∼800 MHz to 12 GHz (e.g., Suresh et al 2023), although few results have yet been published at the newly covered frequencies.…”

Section: Introductionmentioning

confidence: 99%

COSMIC: An Ethernet-based Commensal, Multimode Digital Backend on the Karl G. Jansky Very Large Array for the Search for Extraterrestrial Intelligence

Tremblay,

Varghese,

Hickish

et al. 2023

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The primary goal of the search for extraterrestrial intelligence is to gain an understanding of the prevalence of technologically advanced beings (organic or inorganic) in the Galaxy. One way to approach this is to look for technosignatures: remotely detectable indicators of technology, such as temporal or spectral electromagnetic emissions consistent with an artificial source. With the new Commensal Open-Source Multimode Interferometer Cluster (COSMIC) digital backend on the Karl G. Jansky Very Large Array (VLA), we aim to conduct a search for technosignatures that is significantly more comprehensive, sensitive, and efficient than previously attempted. The COSMIC system is currently operational on the VLA, recording data and designed with the flexibility to provide user-requested modes. This paper describes the hardware system design, the current software pipeline, and plans for future development.

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Searching for Broadband Pulsed Beacons from 1883 Stars Using Neural Networks

Cited by 9 publications

References 44 publications

A 4–8 GHz Galactic Center Search for Periodic Technosignatures

A 4–8 GHz Galactic Center Search for Periodic Technosignatures

Inferring the Rate of Technosignatures from 60 yr of Nondetection

COSMIC: An Ethernet-based Commensal, Multimode Digital Backend on the Karl G. Jansky Very Large Array for the Search for Extraterrestrial Intelligence

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