There's more to life than O2β: Simulating the detectability of a range
of molecules for ground-based high-resolution spectroscopy of transiting
terrestrial exoplanets
Within the next decade, atmospheric O2β on Earth-like M dwarf planets may
be accessible with visible--near-infrared, high spectral resolution extremely
large ground-based telescope (ELT) instruments. However, the prospects for
using ELTs to detect environmental properties that provide context for O2β
have not been thoroughly explored. Additional molecules may help indicate
planetary habitability, rule out abiotically generated O2β, or reveal
alternative biosignatures. To understand the accessibility of environmental
context using ELT spectra, we simulate high-resolution transit transmission
spectra of previously-generated evolved terrestrial atmospheres. We consider
inhabited pre-industrial and Archean Earth-like atmospheres, and lifeless
worlds with abiotic O2β buildup from CO2β and H2βO photolysis. All
atmospheres are self-consistent with M2V--M8V dwarf host stars. Our simulations
include explicit treatment of systematic and telluric effects to model
high-resolution spectra for GMT, TMT, and E-ELT configurations for systems 5
and 12 pc from Earth. Using the cross-correlation technique, we determine the
detectability of major species in these atmospheres: O2β, O3β, CH4β,
CO2β, CO, H2βO, and C2βH6β. Our results suggest that CH4β and CO2β
are the most accessible molecules for terrestrial planets transiting a range of
M dwarf hosts using an E-ELT, TMT, or GMT sized telescope, and that the O2β
NIR and H2βO 0.9 ΞΌm bands may also be accessible with more observation
time. Although this technique still faces considerable challenges, the ELTs
will provide access to the atmospheres of terrestrial planets transiting
earlier-type M-dwarf hosts that may not be possible using JWST.Comment: Accepted for publication in The Planetary Science Journa