DM21cm - Inhomogeneous Energy Injection in 21cm Cosmology

HERA sensitivity to dark matter monochromatic decays in 21-cm power spectrum

Usage

from dm21cm.injections.decay import DMDecayInjection
from dm21cm.evolve import evolve

import py21cmfast as p21c

return_dict = evolve(
    run_name = 'test_injection',
    z_start = 45.,
    z_end = 5.,
    injection = DMDecayInjection(
        primary='phot_delta',
        m_DM=1e8, # [eV]
        lifetime=1e28, # [s]
    ),
    p21c_initial_conditions = p21c.initial_conditions(
        user_params = p21c.UserParams(
            HII_DIM = 64,
            BOX_LEN = 256, # [conformal Mpc]
        ),
    ),
    p21c_astro_params = p21c.AstroParams(),
)

Installation

Prerequisite: DarkHistory

• Clone the DarkHistory repository here. Checkout branch DM21cm.
• Install the require packages via pip install -r requirements.txt.
• Set environment variable DH_DIR to point to the project folder (directory containing README.md).
• Set environment variable DH_DATA_DIR to point to the DarkHistory data (v1.1) folder (directory containing binning.p). The data files can be downloaded here.

Prerequisite: 21cmFAST

• Clone the 21cmFAST fork here. Checkout branch master.
• Install 21cmFAST according to README.md
  • Install gcc and have environment variable CC point to the binary.
  • Install gsl (GNU Scientific Library) and have GSL_LIB point to the directory of the library.
  • Install fftw and have FFTW_INC point to the directory containing fftw header files.
  • Install 21cmFAST via pip install . in the project directory.
• Set environment variable P21C_CACHE_DIR to a directory for storing cached files (requries at least 10G for a 128^3 box 1.01 redshift step run).

DM21cm

• Clone this repository. Checkout branch main.
• Download data files from here.
• Install the require packages via pip install -r requirements.txt. We recommend installing JAX according to your hardware (e.g. GPU) specification.
• Set environment variable DM21CM_DIR to point to the project folder (directory containing README.md).
• Set environment variable DM21CM_DATA_DIR to point to the data folder (directory containing abscissas.h5).

Defining your custom injection

import dm21cm.physics as phys
from dm21cm.injections.base import Injection
from darkhistory.spec import pppc
import numpy as np

class CustomInjection (Injection):

    def __init__(self):
        self.mode = 'Decay implemented again'
        self.primary = primary
        self.m_DM = m_DM
        self.lifetime = lifetime

    #===== injections =====
    def inj_rate(self, z):
        """Injection event rate density in [injection / pcm^3 s]. [pcm] = [physical cm].
        Used in DarkHistory part of the evolution.
        """
        rho_DM = phys.rho_DM * (1+z)**3 # [eV / pcm^3]
        return float((rho_DM/self.m_DM) / self.lifetime) # [inj / pcm^3 s]
    
    def inj_power(self, z):
        """Injection power density in [eV / pcm^3 s].
        Used in DarkHistory.
        """
        return self.inj_rate(z) * self.m_DM # [eV / pcm^3 s]
    
    def inj_phot_spec(self, z, **kwargs):
        """Injected photon rate density spectrum assuming a homogeneous universe in [# / pcm^3 s].
        Used in DarkHistory.
        """
        return self.phot_spec_per_inj * self.inj_rate(z) # [phot / pcm^3 s]
    
    def inj_elec_spec(self, z, **kwargs):
        """Injected electron rate density spectrum assuming a homogeneous universe in [# / pcm^3 s].
        Used in DarkHistory.
        """
        return self.elec_spec_per_inj * self.inj_rate(z) # [elec / pcm^3 s]
    
    def inj_phot_spec_box(self, z, delta_plus_one_box=..., **kwargs):
        """Injected photon rate density spectrum [# / pcm^3 s] and weight box [dimensionless]."""
        return self.inj_phot_spec(z), delta_plus_one_box # [phot / pcm^3 s], [1]

    def inj_elec_spec_box(self, z, delta_plus_one_box=..., **kwargs):
        """Injected electron rate density spectrum [# / pcm^3 s] and weight box [dimensionless]."""
        return self.inj_elec_spec(z), delta_plus_one_box # [elec / pcm^3 s], [1]

    #===== utilities =====
    def set_binning(self, abscs):
        """Inherent binning from `evolve` function."""
        self.phot_spec_per_inj = pppc.get_pppc_spec(
            self.m_DM, abscs['photE'], self.primary, 'phot', decay=True
        ) # [# / injection event]
        self.elec_spec_per_inj = pppc.get_pppc_spec(
            self.m_DM, abscs['elecEk'], self.primary, 'elec', decay=True
        ) # [# / injection event]

    def is_injecting_elec(self):
        """Optionally turn off electron injection."""
        return not np.allclose(self.elec_spec_per_inj.N, 0.)
    
    def get_config(self):
        """For caching darkhistory runs."""
        return {
            'mode': self.mode,
            'primary': self.primary,
            'm_DM': self.m_DM,
            'lifetime': self.lifetime
        }

Authors

Yitian Sun, Joshua W. Foster, Hongwan Liu, Julian B. Muñoz, and Tracy R. Slatyer