One of Everything: The Breakthrough Listen Exotica Catalog (2006.11304v2)

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 non-transient 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 extensive discussion of 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 similar tactics may be applied to other programs.

• The paper introduces a diverse catalog of 963 entries across 816 targets, enhancing SETI by widening the observational scope.
• It employs a rigorous selection method, classifying objects into prototype, superlative, anomaly, and control samples to reduce survey bias.
• The catalog not only advances SETI detection strategies but also underpins broader astrophysical studies and the search for unknown phenomena.

Overview of "The Breakthrough Listen Exotica Catalog"

Introduction

The paper "One of Everything: The Breakthrough Listen Exotica Catalog" authored by Brian C. Lacki et al., introduces the Breakthrough Listen Exotica Catalog. This catalog is crafted to enhance the diversity of targets observed in the Search for Extraterrestrial Intelligence (SETI) by incorporating a wide array of celestial objects. The survey aims to explore the breadth of astrophysical phenomena by compiling a list that spans the full range of known celestial objects.

The Role of Survey Breadth in SETI

The paper discusses several motivations for pursuing a broad survey of extraterrestrial intelligence (ETI). One reason is that a diverse range of objects increases the likelihood of detecting a positive result in SETI. Furthermore, examining various objects is beneficial for broad astrophysical studies and helps in characterizing systematic errors. Therefore, the Exotica Catalog fosters not only SETI but also commensal astrophysical research.

Structure of the Exotica Catalog

The Exotica Catalog consists of 963 entries spanning 816 unique targets, categorized into four distinct groups:

1. Prototype Sample: This includes archetypical examples of various celestial objects. The goal is to cover each major category of non-transient celestial phenomena, augmenting the chances of encountering phenomena linked to ETIs.
2. Superlative Sample: This part of the catalog focuses on objects with extreme properties. These "record-holders" are included to expand the parameter space and cover environments that could potentially host ETIs or unexplained natural phenomena.
3. Anomaly Sample: It consists of enigmatic targets that remain unexplained under current astrophysical theories. These anomalies represent opportunities to discover novel phenomena, possibly indicating technosignatures.
4. Control Sample: Sources unlikely to produce positive results, providing a benchmark to evaluate the potential for instrumental errors.

Methodology and Selection Criteria

The authors detail the methodical process employed to choose entries in the catalog. Each entry within the Prototype sample is selected for its representativeness of a broader class of objects, ensuring a wide survey coverage. Superlatives are chosen based on their extremity among observed phenomena, while anomalies are picked due to their unresolved nature in scientific literature.

The catalog reflects a rigorous approach wherein previous studies, classification systems, and scientific reviews are integral to determining each entry. This meticulous effort culminates in an extensive classification system balancing coverage and manageability.

Implications and Strengths

The Breakthrough Listen Exotica Catalog is a significant asset to the SETI community because it systematically addresses the longstanding issue of survey bias towards sunlike stars or localized areas of the sky. By encompassing a broad array of celestial phenomena, it enhances the chances of an incidental but meaningful detection of ETIs or unknown astrophysical processes.

Moreover, this catalog sets a precedent for similar broad surveys using new facilities across various parts of the electromagnetic spectrum and other messengers like neutrinos or gravitational waves. It promotes the practice of casting a wide net in the search for unfamiliar cosmic phenomena, a strategy that is invaluable as the limits of technology and observation continually advance.

Future Directions

The catalog promises future revisions as our understanding of the cosmos deepens and further anomalies are uncovered. It also suggests the potential expansion of the initiative beyond just radio and optical observations to encompass a treasury survey of astrophysical objects in all obtainable freequency regimes.

In conclusion, the Breakthrough Listen Exotica Catalog is an ambitious and well-structured effort to push the boundary of traditional SETI searches. It presents an opportunity for serendipitous discoveries, while also building a rich database for broader astronomical utility.