Source code for gammapy.astro.darkmatter.utils

# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""Utilities to compute J-factor maps."""
import astropy.units as u

__all__ = ["JFactory"]

[docs]class JFactory: """Compute J-Factor maps. All J-Factors are computed for annihilation. The assumed dark matter profiles will be centered on the center of the map. Parameters ---------- geom : `~gammapy.maps.WcsGeom` Reference geometry profile : `~gammapy.astro.darkmatter.profiles.DMProfile` Dark matter profile distance : `~astropy.units.Quantity` Distance to convert angular scale of the map """ def __init__(self, geom, profile, distance): self.geom = geom self.profile = profile self.distance = distance
[docs] def compute_differential_jfactor(self): r"""Compute differential J-Factor. .. math:: \frac{\mathrm d J}{\mathrm d \Omega} = \int_{\mathrm{LoS}} \mathrm d r \rho(r) """ # TODO: Needs to be implemented more efficiently separation = self.geom.separation(self.geom.center_skydir) rmin = separation.rad * self.distance rmax = self.distance val = [self.profile.integral(_, rmax) for _ in rmin.flatten()] jfact = u.Quantity(val).to("GeV2 cm-5").reshape(rmin.shape) return jfact / u.steradian
[docs] def compute_jfactor(self): r"""Compute astrophysical J-Factor. .. math:: J(\Delta\Omega) = \int_{\Delta\Omega} \mathrm d \Omega^{\prime} \frac{\mathrm d J}{\mathrm d \Omega^{\prime}} """ diff_jfact = self.compute_differential_jfactor() return diff_jfact * self.geom.to_image().solid_angle()