Transmission Spectroscopy

Uses ArtTransPure class

To calculate the transmission spectrum in ExoJAX, the ArtTransPure class is convenient. For chord integration, one can choose either Simpson’s method or the trapezoidal method from the integration options. Here is the example of the computation of the transmission radius. We here use Simpson’s rule for the chord integration.

In transmission spectroscopy, assuming a constant gravity across the layers is often not a good approximation. The gravity_profile instance in the ArtTransPure class allows for easy calculation of the gravity profile, addressing this concern in ExoJAX.

from exojax.spec.atmrt import ArtTransPure
from exojax.utils.constants import RJ

art = ArtTransPure(pressure_top=1.e-8, pressure_btm=1.e2, nlayer=100, integration="simpson") # integration="trapezoid" if you want
art.change_temperature_range(400.0, 1500.0)
Tarr = art.powerlaw_temperature(1300.0, 0.1)
mmr_arr = art.constant_mmr_profile(0.1) # constant mass mixing ratio profile
mmw = 2.33 * np.ones_like(art.pressure) # mean molecular weight profile
gravity_btm = 2478.57
radius_btm = RJ
gravity = art.gravity_profile(Tarr, mmw, radius_btm, gravity_btm) # computes gravity profile

opa = OpaPremodit(mdb=mdb,
                  nu_grid=nu_grid,
                  auto_trange=[art.Tlow, art.Thigh])

xsmatrix = opa.xsmatrix(Tarr, art.pressure)

dtau = art.opacity_profile_xs(xsmatrix, mmr_arr, opa.mdb.molmass,gravity)
Rp2 = art.run(dtau, Tarr, mmw, radius_btm, gravity_btm)