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arXiv · 1710.10269

A library of ATMO forward model transmission spectra for hot Jupiter exoplanets

Jayesh M. Goyal·Nathan Mayne·David K. Sing·Benjamin Drummond·Pascal Tremblin·David S. Amundsen·Thomas Evans·Aarynn L. Carter·Jessica Spake·Isabelle Baraffe·Nikolay Nikolov·James Manners·Gilles Chabrier·Eric Hebrard
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Abstract

We present a grid of forward model transmission spectra, adopting an isothermal temperature-pressure profile, alongside corresponding equilibrium chemical abundances for 117 observationally significant hot exoplanets (Equilibrium Temperatures of 547-2710 K). This model grid has been developed using a 1D radiative-convective-chemical equilibrium model termed ATMO, with up-to-date high temperature opacities. We present an interpretation of observations of ten exoplanets, including best fit parameters and $χ^{2}$ maps. In agreement with previous works, we find a continuum from clear to hazy/cloudy atmospheres for this sample of hot Jupiters. The data for all the 10 planets are consistent with sub-solar to solar C/O ratio, 0.005 to 10 times solar metallicity and water rather than a methane dominated infrared spectra. We then explore the range of simulated atmospheric spectra for different exoplanets, based on characteristics such as temperature, metallicity, C/O-ratio, haziness and cloudiness. We find a transition value for the metallicity between 10 and 50 times solar, which leads to substantial changes in the transmission spectra. We also find a transition value of C/O ratio, from water to carbon species dominated infrared spectra, as found by previous works, revealing a temperature dependence of this transition point ranging from $\sim$0.56 to $\sim$1-1.3 for equilibrium temperatures from $\sim$900 to $\sim$2600 K. We highlight the potential of the spectral features of HCN and C$_2$H$_2$ to constrain the metallicities and C/O ratios of planets, using JWST observations. Finally, our entire grid ($\sim$460,000 simulations) is publicly available and can be used directly with the JWST simulator PandExo for planning observations.

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Jayesh M. Goyal, Nathan Mayne, David K. Sing, Benjamin Drummond, Pascal Tremblin, David S. Amundsen, Thomas Evans, Aarynn L. Carter, Jessica Spake, Isabelle Baraffe, Nikolay Nikolov, James Manners, Gilles Chabrier, Eric Hebrard. 2020-07-30. A library of ATMO forward model transmission spectra for hot Jupiter exoplanets. https://doi.org/10.1093/mnras%2Fstx3015

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