An Overview of Exoplanet Biosignatures

TL;DR

This chapter provides a comprehensive overview of various exoplanet biosignatures, including gaseous, surface, and temporal indicators, emphasizing recent research and frameworks for remote detection.

Contribution

It offers an updated synthesis of proposed biosignatures, integrating recent findings and discussing assessment frameworks for remote exoplanet biosignature detection.

Findings

Identification of key gaseous biosignatures like O2, CH4, and NH3.

Discussion of surface biosignatures such as vegetation red edge and pigment features.

Presentation of frameworks for evaluating remote biosignatures.

Abstract

This chapter reviews proposed exoplanet biosignatures, including their biological origins, observable features, atmospheric sinks, and potentially confounding abiotic sources. Emphasis is placed on material published since past comprehensive reviews while providing a foundational understanding of each named biosignature. Topics include possible gaseous biosignatures (e.g., O$_2$, O$_3$, CH$_4$, N$_2$O, DMS, CH$_3$Cl, C$_5$H$_8$, NH$_3$, PH$_3$), surface biosignatures (e.g., vegetation red edge, other pigment features, polarization signatures), and temporal biosignatures (e.g., atmospheric seasonality). Potential frameworks for assessing remote biosignatures are described. Text and table summaries provide references to relevant original research articles.