# mypy: disable-error-code="operator,dict-item"
from typing import Optional, Union, Annotated
from caskade import forward, Param
from ..backend_obj import ArrayLike
from .base import ThinLens, CosmologyType, NameType, ZType
from . import func
__all__ = ("MassSheet",)
[docs]
class MassSheet(ThinLens):
"""
Represents an external shear effect in a gravitational lensing system.
Attributes
----------
name: string
Identifier for the lens instance.
cosmology: Cosmology
The cosmological model used for lensing calculations.
z_l: Optional[Union[ArrayLike, float]]
The redshift of the lens.
*Unit: unitless*
z_s : Optional[Union[ArrayLike, float]]
The redshift of the source.
*Unit: unitless*
x0: Optional[Union[ArrayLike, float]]
x-coordinate of the shear center in the lens plane.
*Unit: arcsec*
y0: Optional[Union[ArrayLike, float]]
y-coordinate of the shear center in the lens plane.
*Unit: arcsec*
kappa: Optional[Union[ArrayLike, float]]
Convergence. Surface density normalized by the critical surface density.
*Unit: unitless*
"""
_null_params = {
"x0": 0.0,
"y0": 0.0,
"kappa": 0.1,
}
def __init__(
self,
cosmology: CosmologyType,
z_l: ZType = None,
z_s: ZType = None,
x0: Annotated[
Optional[Union[ArrayLike, float]],
"x-coordinate of the shear center in the lens plane",
True,
] = None,
y0: Annotated[
Optional[Union[ArrayLike, float]],
"y-coordinate of the shear center in the lens plane",
True,
] = None,
kappa: Annotated[
Optional[Union[ArrayLike, float]], "Surface density", True
] = None,
name: NameType = None,
):
super().__init__(cosmology, z_l, name=name, z_s=z_s)
self.x0 = Param("x0", x0, shape=(), units="arcsec")
self.y0 = Param("y0", y0, shape=(), units="arcsec")
self.kappa = Param("kappa", kappa, shape=(), units="unitless")
[docs]
@forward
def reduced_deflection_angle(
self,
x: ArrayLike,
y: ArrayLike,
x0: Annotated[ArrayLike, "Param"],
y0: Annotated[ArrayLike, "Param"],
kappa: Annotated[ArrayLike, "Param"],
) -> tuple[ArrayLike, ArrayLike]:
"""
Calculates the reduced deflection angle.
Parameters
----------
x: ArrayLike
x-coordinates in the lens plane.
*Unit: arcsec*
y: ArrayLike
y-coordinates in the lens plane.
*Unit: arcsec*
Returns
-------
x_component: ArrayLike
Deflection Angle in x-direction.
*Unit: arcsec*
y_component: ArrayLike
Deflection Angle in y-direction.
*Unit: arcsec*
"""
return func.reduced_deflection_angle_mass_sheet(x0, y0, kappa, x, y)
[docs]
@forward
def potential(
self,
x: ArrayLike,
y: ArrayLike,
x0: Annotated[ArrayLike, "Param"],
y0: Annotated[ArrayLike, "Param"],
kappa: Annotated[ArrayLike, "Param"],
) -> ArrayLike:
# Meneghetti eq 3.81
return func.potential_mass_sheet(x0, y0, kappa, x, y)
[docs]
@forward
def convergence(
self,
x: ArrayLike,
y: ArrayLike,
kappa: Annotated[ArrayLike, "Param"],
) -> ArrayLike:
# Essentially by definition
return func.convergence_mass_sheet(kappa, x)
