Created
October 25, 2023 14:32
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Compute growing mode solution
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| from scipy.integrate import quad | |
| class Cosmology: | |
| """This object stores all relevant information wrt the background | |
| cosmology, parametrized by OmegaM, OmegaL and H0.""" | |
| def __init__(self, H0, OmegaM, OmegaL): | |
| self.H0 = H0 | |
| self.OmegaM = OmegaM | |
| self.OmegaL = OmegaL | |
| self.OmegaK = 1 - OmegaM - OmegaL | |
| self.grav_cst = 3./2 * OmegaM * H0**2 | |
| self.factor = self._growing_mode_norm() | |
| def adot(self, a): | |
| return self.H0 * a * np.sqrt(self.OmegaL \ | |
| + self.OmegaM * a**-3 \ | |
| + self.OmegaK * a**-2) | |
| def _growing_mode_norm(self): | |
| """result D(1) = 1. d/d0 + 0.001 = 1""" | |
| d = self.adot(1) * quad(lambda b: self.adot(b)**(-3), 0.00001, 1)[0] | |
| return 0.99999/d | |
| def growing_mode(self, a): | |
| if isinstance(a, np.ndarray): | |
| return np.array([self.growing_mode(b) for b in a]) | |
| elif a <= 0.001: | |
| return a | |
| else: | |
| return self.factor * self.adot(a)/a * quad(lambda b: self.adot(b)**(-3), 0.00001, a)[0] + 0.00001 | |
| def __call__(self, a): | |
| return self.adot(a) | |
| LCDM = Cosmology(68.0, 0.31, 0.69) | |
| EdS = Cosmology(70.0, 1.0, 0.0) |
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