One of Everything: The Breakthrough Listen Exotica Catalog

Abstract

We present Breakthrough Listen’s Exotica Catalog as the centerpiece of our efforts to expand the diversity of targets surveyed in the Search for Extraterrestrial Intelligence (SETI). As motivation, we introduce the concept of survey breadth, the diversity of objects observed during a program. Several reasons for pursuing a broad program are given, including increasing the chance of a positive result in SETI, commensal astrophysics, and characterizing systematics. The Exotica Catalog is a 963 entry collection of 816 distinct targets intended to include “one of everything” in astronomy. It contains four samples: the Prototype sample, with an archetype of every known major type of nontransient celestial object; the Superlative sample of objects, with the most extreme properties; the Anomaly sample of enigmatic targets that are in some way unexplained; and the Control sample, with sources not expected to produce positive results. As far as we are aware, this is the first object list in recent times with the purpose of spanning the breadth of astrophysics. We share it with the community in hopes that it can guide treasury surveys and as a general reference work. Accompanying the catalog is an extensive discussion of the classification of objects and a new classification system for anomalies. Extensive notes on the objects in the catalog are available online. We discuss how we intend to proceed with observations in the catalog, contrast it with our extant Exotica efforts, and suggest how similar tactics may be applied to other programs.

A 4–8 GHz Galactic Center Search for Periodic Technosignatures

“…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.…”

“…In addition, such leakage signals are likely to be weaker. Hence, modern radio SETI efforts have primarily focused on wideband searches for deliberate narrowband (Δν ∼ 1 Hz) Doppler-drifting beacons from Galactic planetary systems (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 neighboring galaxies (Gray & Mooley 2017;Lacki et al 2021;Garrett & Siemion 2023).…”

Constraints on extragalactic transmitters via Breakthrough Listen

“…For this sample, NED also reports spectroscopic redshifts for 989 objects and photometric redshifts for 434 objects. Clearly many of the objects fall into the category of "astrophysical exotica" as defined earlier by Lacki et al (2021). In the following sub-sections, some examples of the wide range of various exotica are presented, with an emphasis on those systems that are relatively nearby and for which some constraints on the nature and prevalence of powerful transmitters may be inferred.…”

“…In a very welcome effort to expand the diversity of targets surveyed by the BL Initiative, Lacki et al (2021) has compiled an additional catalogue of possible targets, with the ambition of including "one of everything" -a complete range of cosmic phenomena or astrophysical "exotica". The catalogue includes 816 distinct targets and is remarkably wide ranging, including minor bodies of the solar system, planetoids, giant planets, stars, collapsed objects, stellar groups, nebulae and the ISM, galaxies, active galactic nuclei (AGN), galaxy associations, and large-scale structures.…”

Simulating high-time resolution radio-telescope observations

“…The Australian Square Kilometre Array Pathfinder (ASKAP) telescope has commenced widefield imaging surveys, such as the Widefield ouTlier Finder (WTF project), which is already finding unexpected source types (e.g., Norris et al 2021). Similar searches for extraterrestrial intelligence (SETI) are being carried out in high-time resolution data sets (Lacki et al 2021). Very recently, the Parkes Breakthrough Listen observations detected a suspicious signal ('blc1') at around 982 MHz towards Proxima Centauri (Smith et al 2021), which turned out to have terrestrial origin after detailed analysis (Sheikh et al 2021).…”