tokens: we apply the formalism of Brogi Line ( 2019 ). We compute the log-likelihood function of each tested model by combining the data and model variances, and the cross-covariance of data and model according to their equation (9). We assume the same total observing time as for the data set presented in Benneke et al. ( 2019 ), which is 8.4 h. Since HRS does not necessarily need out-of-transit data, this integration time would allow us to observe four full transits of the exoplanet. Our results are shown in Fig. 5 . We can successfully and confidently (>5σ) recover the H 2 O signal for all instruments at the expected values of K p and V sys , as shown by the fact that the injection values (white crosses) are within or just outside the 1σ confidence interval. Given the relatively strong detection achieved, we conclude that the best-fitting atmospheric scenario for GJ 3470b would be easily detectable with current HRS with a relatively modest investment of telescope time. The size of the confidence intervals also suggests that GIANO and SPIRou are, respectively, the least and the most sensitive instruments based on our simulations. Note that CARMENES does not cover the K band unlike the other two spectrographs but does still show a strong H 2 O detection because of its high throughput. Figure 5. Detectability of the best-fitting atmospheric scenario for exoplanet GJ 3470b as derived by Benneke et al. ( 2019 ), based on 8 h (4 transits) of simulated observations with three near-infrared high-resolution spectrographs. Shown in the plot are confidence intervals on the rest-frame velocity and radial-velocity amplitude of the planet after the likelihood of Brogi Line ( 2019 ) has been applied to the simulated data. The white cross indicated the simulated values. 3.2 Constraining H<sub>2</sub>O and cloud decks – GJ 436b We now discuss how HRS may be able to constrain abundances and cloud decks on GJ 436b using the grid of model spectra discussed in Section 2.1.2 . We chose this planet as observations of the primary transit have revealed a largely featureless spectrum (Knutson et al. 2014a ). The only constraints on H 2 O thus far have been derived from low-resolution secondary eclipse observations (Stevenson et al. 2010 ). In Fig. 6 , we show three representative high-resolution transmission models with varying H 2 O and cloud top pressures but which resulted in similar muted HST WFC3 features. We studied their detectability with CARMENES, GIANO, and SPIRou, and the ability to discriminate cloudy scenarios from high-metallicity scenarios as shown in Fig. 2 . Figure 6. Model transmission spectra and binned HST WFC3 spectral points for GJ 436b. These are shown for three cases with varying cloud pressures and H 2 O abundances. The high-resolution spectra have been binned to the Knutson et al. ( 2014a ) observations, which are also shown with their associated error bars. We offset the models in the figure to highlight the spectral features. Fig. 6 shows the three
ner_tags: O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O B-Instrument O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength O B-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O B-Instrument O B-Instrument O O O O O O O O O O O O O O O B-Instrument O O O O B-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O B-Wavelength O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O B-Tag O O O O B-CelestialObject I-CelestialObject O O O O B-Instrument O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope B-Instrument O O O O O O B-Instrument B-Instrument O B-Instrument O O O O O O O O O O O O O O O O O O O O O O O B-Telescope B-Instrument O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O