Atmospheric Circulation of Hot Jupiters: Dayside-Nightside Temperature Differences. II. Comparison with Observations. (arXiv:1610.03893v4 [astro-ph.EP] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Komacek_T/0/1/0/all/0/1">Thaddeus D. Komacek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Showman_A/0/1/0/all/0/1">Adam P. Showman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tan_X/0/1/0/all/0/1">Xianyu Tan</a>
The full-phase infrared light curves of low-eccentricity hot Jupiters show a
trend of increasing fractional dayside-nightside brightness temperature
difference with increasing incident stellar flux, both averaged across the
infrared and in each individual wavelength band. The analytic theory of Komacek
& Showman (2016) shows that this trend is due to the decreasing ability with
increasing incident stellar flux of waves to propagate from day to night and
erase temperature differences. Here, we compare the predictions of this theory
to observations, showing that it explains well the shape of the trend of
increasing dayside-nightside temperature difference with increasing equilibrium
temperature. Applied to individual planets, the theory matches well with
observations at high equilibrium temperatures but, for a fixed photosphere
pressure of $100 mathrm{mbar}$, systematically under-predicts the
dayside-nightside brightness temperature differences at equilibrium
temperatures less than $2000 mathrm{K}$. We interpret this as due to as the
effects of a process that moves the infrared photospheres of these cooler hot
Jupiters to lower pressures. We also utilize general circulation modeling with
double-grey radiative transfer to explore how the circulation changes with
equilibrium temperature and drag strengths. As expected from our theory, the
dayside-nightside temperature differences from our numerical simulations
increase with increasing incident stellar flux and drag strengths. We calculate
model phase curves using our general circulation models, from which we compare
the broadband infrared offset from the substellar point and dayside-nightside
brightness temperature differences against observations, finding that strong
drag or additional effects (e.g. clouds and/or supersolar metallicities) are
necessary to explain many observed phase curves.
The full-phase infrared light curves of low-eccentricity hot Jupiters show a
trend of increasing fractional dayside-nightside brightness temperature
difference with increasing incident stellar flux, both averaged across the
infrared and in each individual wavelength band. The analytic theory of Komacek
& Showman (2016) shows that this trend is due to the decreasing ability with
increasing incident stellar flux of waves to propagate from day to night and
erase temperature differences. Here, we compare the predictions of this theory
to observations, showing that it explains well the shape of the trend of
increasing dayside-nightside temperature difference with increasing equilibrium
temperature. Applied to individual planets, the theory matches well with
observations at high equilibrium temperatures but, for a fixed photosphere
pressure of $100 mathrm{mbar}$, systematically under-predicts the
dayside-nightside brightness temperature differences at equilibrium
temperatures less than $2000 mathrm{K}$. We interpret this as due to as the
effects of a process that moves the infrared photospheres of these cooler hot
Jupiters to lower pressures. We also utilize general circulation modeling with
double-grey radiative transfer to explore how the circulation changes with
equilibrium temperature and drag strengths. As expected from our theory, the
dayside-nightside temperature differences from our numerical simulations
increase with increasing incident stellar flux and drag strengths. We calculate
model phase curves using our general circulation models, from which we compare
the broadband infrared offset from the substellar point and dayside-nightside
brightness temperature differences against observations, finding that strong
drag or additional effects (e.g. clouds and/or supersolar metallicities) are
necessary to explain many observed phase curves.
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