skyscapes.disk.grater ===================== .. py:module:: skyscapes.disk.grater .. autoapi-nested-parse:: GraterDisk: Augereau 1999 scattered-light disk as an eqx.Module. The Augereau et al. 1999 model is a two-power-law dust density distribution with a flared vertical profile, scattering with a single Henyey-Greenstein phase function. This module exposes the model in skyscapes' eqx.Module idiom so its parameters are PyTree leaves (fittable through the standard scene-as-PyTree pattern). References: Augereau, J.-C., Lagrange, A.-M., Mouillet, D., Papaloizou, J. C. B., & Grorod, P. A. 1999, A&A, 348, 557 grater-jax (Kondapalli, Lewis, Ashcraft, Millar-Blanchaer): https://github.com/UCSB-Exoplanet-Polarimetry-Lab/GRaTeR-JAX Notes on convention: Disk orientation (``incl_deg`` / ``pa_deg``) is passed in at ``surface_brightness`` time rather than stored on the disk -- the System's ``midplane_inc_deg`` / ``midplane_pa_deg`` drives every component consistently and there is one source of truth. Wavelength dependence enters via the HG asymmetry parameter ``g_HG`` and the albedo-like scaling ``Ag``, both stored as 1-D grids over ``wavelengths_nm`` and interpolated at call time with a cubic spline. The geometric kernel itself is wavelength-independent, so ``surface_brightness`` keeps its scalar-in / ``(ny, nx)``-out shape contract; ``vmap`` over wavelength gives a cube without changing the interface. The LOS-around-midplane sampling diverges at edge-on geometry (``cos(incl) -> 0``); ``surface_brightness`` raises via ``eqx.error_if`` if the requested inclination is closer to edge-on than the disk's geometric capacity allows. The threshold is ``arctan(rmax_AU / zmax_AU)`` where ``zmax_AU`` is evaluated at the outer disk radius after flaring. Classes ------- .. autoapisummary:: skyscapes.disk.grater.GraterDisk Functions --------- .. autoapisummary:: skyscapes.disk.grater.henyey_greenstein skyscapes.disk.grater.two_power_law_density Module Contents --------------- .. py:function:: henyey_greenstein(cos_phi, g) Henyey-Greenstein single-scattering phase function. Args: cos_phi: Cosine of scattering angle, any broadcastable shape. g: Asymmetry parameter in (-1, 1). g > 0 is forward-peaked, g < 0 is backward-peaked, g = 0 is isotropic. Returns: Phase function value, same shape as ``cos_phi``. .. py:function:: two_power_law_density(r, z, sma_AU, alpha_in, alpha_out, ksi0_AU, gamma, beta) Augereau 1999 two-power-law radial density with flared vertical profile. Args: r: Cylindrical radius in disk frame [AU]. Must be strictly positive; callers are responsible for masking r values that are too small for the radial power law to evaluate cleanly in the chosen dtype (e.g. r_ratio^(-2 alpha_in) overflows float32 below r/sma ~ 1e-3 at alpha_in = 5). z: Height above disk midplane [AU]. sma_AU: Reference radius (radial profile peak) [AU]. alpha_in: Inner power-law slope (positive convention). alpha_out: Outer power-law slope (negative convention). ksi0_AU: Vertical scale height at ``r = sma_AU`` [AU]. gamma: Vertical profile exponent (2 = Gaussian, 1 = exponential). beta: Flaring index (0 = none, 1 = linear). Returns: Density in arbitrary units (relative), same shape as ``r`` and ``z``. .. py:class:: GraterDisk Bases: :py:obj:`skyscapes.disk.base.AbstractDisk` Augereau 1999 scattered-light disk. Attributes (PyTree leaves, fittable): sma_AU: Reference radius [AU] (radial profile peak). alpha_in: Inner power-law slope (positive). alpha_out: Outer power-law slope (negative). ksi0_AU: Vertical scale height at ``sma_AU`` [AU]. gamma: Vertical profile exponent (2 = Gaussian). beta: Flaring index (0 = none, 1 = linear). rmin_AU: Inner truncation radius [AU]. rmax_AU: Outer truncation radius [AU]. wavelengths_nm: 1-D wavelength grid for ``g_HG_grid`` / ``Ag_grid``, shape ``(n_wave,)`` [nm]. Must be sorted. ``surface_brightness`` calls outside this range return NaN. g_HG_grid: Henyey-Greenstein asymmetry at each grid wavelength. Ag_grid: Albedo-like scaling at each grid wavelength. Static attributes (compilation-time constants): nx, ny: Output image shape. pixel_scale_arcsec: Pixel scale [arcsec/pixel]. dist_pc: System distance [pc]. n_slices_los: Number of LOS integration slices. n_scale_heights: LOS half-extent in units of the local scale height at ``rmax_AU`` (default 6.0). .. py:attribute:: sma_AU :type: jaxtyping.Array .. py:attribute:: alpha_in :type: jaxtyping.Array .. py:attribute:: alpha_out :type: jaxtyping.Array .. py:attribute:: ksi0_AU :type: jaxtyping.Array .. py:attribute:: gamma :type: jaxtyping.Array .. py:attribute:: beta :type: jaxtyping.Array .. py:attribute:: rmin_AU :type: jaxtyping.Array .. py:attribute:: rmax_AU :type: jaxtyping.Array .. py:attribute:: wavelengths_nm :type: jaxtyping.Array .. py:attribute:: g_HG_grid :type: jaxtyping.Array .. py:attribute:: Ag_grid :type: jaxtyping.Array .. py:attribute:: nx :type: int .. py:attribute:: ny :type: int .. py:attribute:: pixel_scale_arcsec :type: float .. py:attribute:: dist_pc :type: float .. py:attribute:: n_slices_los :type: int .. py:attribute:: n_scale_heights :type: float .. py:method:: _zmax_AU() LOS half-extent in disk-frame z, evaluated at ``rmax_AU``. For a flared disk, the scale height grows with radius, so the LOS depth that captures the vertical tails at the outer edge is larger than ``n_scale_heights * ksi0_AU`` at ``sma_AU``. .. py:method:: surface_brightness(wavelength_nm, time_jd, incl_deg, pa_deg) Render the Augereau 1999 scattered-light disk on a sky-plane grid. ``wavelength_nm`` selects ``g_HG`` and ``Ag`` via cubic-spline interpolation over ``wavelengths_nm`` / ``g_HG_grid`` / ``Ag_grid``. Queries outside the grid return NaN. ``time_jd`` is part of the AbstractDisk interface but ignored (static disk). .. py:method:: spatial_extent() Return ``(width_arcsec, height_arcsec)``. .. py:method:: __repr__() Compact summary of radial/vertical/HG parameters + image/Ag grid.