Fig. 3: Simulated reflected-light spectra for Proterozoic Earth cases.
From: Inferring chemical disequilibrium biosignatures for Proterozoic Earth-like exoplanets
a–c, The x axes indicate the wavelength in micrometres and the y axes represent the planet-to-star flux ratio. a, Simulated reflected-light spectrum for the high-abundance case (green). Absorption features for O3 (brown), CO2 (blue), CH4 (yellow) and O2 (red) are shown and their input abundances are multiplied by a factor of 2. Water vapour absorption features are labelled with text. The legend for the grey error bars shows the scaling for each noise instance (SNR = 20, 30 or 50). The inset highlights the O2 A-band feature at 0.76 μm. b, Simulated reflected-light spectrum for the medium-abundance case (purple). Each input abundance is multiplied by a factor of 2 to show its effect. c, Simulated reflected-light spectrum for the low-abundance case (blue). The denoted species absorption features are shown and their input abundances are multiplied by a factor of 2.
