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Juno Jupiter image

Dr Jake Taylor (he/him)

Schmidt AI in Science Fellow

Research theme

  • Astronomy and astrophysics
  • Exoplanets and planetary physics

Sub department

  • Atmospheric, Oceanic and Planetary Physics

Research groups

  • Exoplanet atmospheres
  • Exoplanets and Stellar Physics
jake.taylor@physics.ox.ac.uk
Atmospheric Physics Clarendon Laboratory, room 309
  • About
  • Publications

Another look at the dayside spectra of WASP-43b and HD 209458b: are there scattering clouds?

ArXiv 2307.08148 (2023)

Authors:

Jake Taylor, Vivien Parmentier
Details from ArXiV

Awesome SOSS: atmospheric characterization of WASP-96 b using the JWST early release observations

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 524:1 (2023) 817-834

Authors:

Jake Taylor, Michael Radica, Luis Welbanks, Ryan J MacDonald, Jasmina Blecic, Maria Zamyatina, Alexander Roth, Jacob L Bean, Vivien Parmentier, Louis-Philippe Coulombe, Adina D Feinstein, Nestor Espinoza, Bjorn Benneke, David Lafreniere, Rene Doyon, Eva-Maria Ahrer
More details from the publisher

Impact of variable photospheric radius on exoplanet atmospheric retrievals

Monthly Notices of the Royal Astronomical Society: Letters 513:1 (2022) L20-L24

Abstract:

Inverse techniques are used to extract information about an exoplanet's atmosphere. These techniques are prone to biased results if the appropriate forward model is not used. One assumption used in a forward model is to assume that the radius of the planet is constant with wavelength; however, a more realistic assumption is that the photospheric radius varies with each wavelength. We explore the bias induced when attempting to extract the molecular abundance from an emission spectrum, which was generated with a variable radius. We find that for low-gravity planets, the retrieval model is not able to fit the data if a constant radius model is used. We find that biased results are obtained when studying a typical hot Jupiter in the MIRI LRS wavelength range. Finally, we show that high-gravity planets do not suffer a bias. We recommend that future spectral retrievals that interpret exoplanet emission spectra should take into account a variable radius.
More details from the publisher

How does thermal scattering shape the infrared spectra of cloudy exoplanets? A theoretical framework and consequences for atmospheric retrievals in the JWST era

Monthly Notices of the Royal Astronomical Society Oxford University Press 506:1 (2021) 1309-1332

Authors:

Jake Taylor, Vivien Parmentier, Michael R Line, Graham KH Lee, Patrick GJ Irwin, Suzanne Aigrain

Abstract:

Observational studies of exoplanets are suggestive of a ubiquitous presence of clouds. The current modelling techniques used in emission to account for the clouds tend to require prior knowledge of the cloud condensing species and often do not consider the scattering effects of the cloud. We explore the effects that thermal scattering has on the emission spectra by modelling a suite of hot Jupiter atmospheres with varying cloud single-scattering albedos (SSAs) and temperature profiles. We examine cases ranging from simple isothermal conditions to more complex structures and physically driven cloud modelling. We show that scattering from nightside clouds would lead to brightness temperatures that are cooler than the real atmospheric temperature if scattering is unaccounted for. We show that scattering can produce spectral signatures in the emission spectrum even for isothermal atmospheres. We identify the retrieval degeneracies and biases that arise in the context of simulated JWST spectra when the scattering from the clouds dominates the spectral shape. Finally, we propose a novel method of fitting the SSA spectrum of the cloud in emission retrievals, using a technique that does not require any prior knowledge of the cloud chemical or physical properties.
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Details from ORA
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Details from ArXiV

Understanding and mitigating biases when studying inhomogeneous emission spectra with JWST

Monthly Notices of the Royal Astronomical Society Royal Astronomical Society 493:3 (2020) 4342-4354,

Authors:

Jake Taylor, Vivien Parmentier, Patrick Irwin, Suzanne Aigrain, Graham Lee, Joshua Krissansen-Totton

Abstract:

Exoplanet emission spectra are often modelled assuming that the hemisphere observed is well represented by a horizontally homogenized atmosphere. However, this approximation will likely fail for planets with a large temperature contrast in the James Webb Space Telescope (JWST) era, potentially leading to erroneous interpretations of spectra. We first develop an analytic formulation to quantify the signal-to-noise ratio and wavelength coverage necessary to disentangle temperature inhomogeneities from a hemispherically averaged spectrum. We find that for a given signal-to-noise ratio, observations at shorter wavelengths are better at detecting the presence of inhomogeneities. We then determine why the presence of an inhomogeneous thermal structure can lead to spurious molecular detections when assuming a fully homogenized planet in the retrieval process. Finally, we quantify more precisely the potential biases by modelling a suite of hot Jupiter spectra, varying the spatial contributions of a hot and a cold region, as would be observed by the different instruments of JWST/NIRSpec. We then retrieve the abundances and temperature profiles from the synthetic observations. We find that in most cases, assuming a homogeneous thermal structure when retrieving the atmospheric chemistry leads to biased results, and spurious molecular detection. Explicitly modelling the data using two profiles avoids these biases, and is statistically supported provided the wavelength coverage is wide enough, and crucially also spanning shorter wavelengths. For the high contrast used here, a single profile with a dilution factor performs as well as the two-profile case, with only one additional parameter compared to the 1D approach.
More details from the publisher
Details from ORA
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Details from ArXiV

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