Core Modules

This page describes the core modules that users are likely to interface most frequently.

The two classes Source and ALP are helper classes which store information about the assumed astrophysical source (like its redshift) and about the assumed ALP, in particular its mass and its coupling to photons.

For instance, a source is initialized in this way, providing the redshift and the sky coordinates:

src = Source(z=0.859, ra='22h53m57.7s', dec='+16d08m54s')

The ALP class is initialized by simply providing values for the ALP mass (in nano electron volts, \(\mathrm{neV}\equiv 10^{-9}\,\mathrm{eV}\)) and the coupling to photons, \(g_{a\gamma}\) in units of \(10^{-11}\,\mathrm{GeV}^{-1}\).

from gammaALPs.core import ALP
alp = ALP(m = 1., g = 1.)
print (alp.m, alp.g)

With the initialized Source and ALP classes, we can now initialize the ModuleList class. This class stores the astrophysical environments in which we would like to calculate the photon-ALP propagation in the modules() property. This is essentially a list of environments with its first entry being the environment closest to the source and the last entry the environment closest to the observer. The ModuleList is initialized like this:

from gammaALPs.core import ModuleList
ml = ModuleList(alp, src)

Environments are added with the add_propagation() function and the overall conversion probability is then calculated by running run(). Details on the available environments are available on the Implemented Astrophysical Environments page.

The usage of these core classes is further demonstrated in the Tutorials.

Reference / API

class gammaALPs.core.Source(z, **kwargs)[source]

Bases: object

Class that stores information about the source: redshift Sky coordinates: ra, dec, l,b As well as jet parameters: bulk Lorentz factor, observation and jet opening angle

__init__(z, **kwargs)[source]

Initialize the source class

Parameters:

  • z (float) – source redshift

  • ra (float or string) – Right Ascension compatible with SkyCoord object

  • dec (float or string) – Declination compatible with SkyCoord object

  • l (float) – Galactic longitude or None. If given, overwrites ra and dec

  • b (float) – Galactic latitude or None. If given, overwrites ra and dec

  • theta_obs (float) – Angle between l.o.s. and jet axis in degrees (default: 3.)

  • bLorentz (float) – bulk lorentz factor of gamma-ray emitting plasma (default: 10.)

  • theta_jet (float) – Jet opening angle in degrees. Default: 1/bLorentz

property b
property bLorentz
property c
property c_gal
calc_doppler()[source]

Calculate the Doppler factor of the plasma

property dec
property l
property ra
set_ra_dec_l_b(ra, dec, l=None, b=None)[source]

Set l and b or ra and dec

property theta_jet
property theta_obs
property z
class gammaALPs.core.ALP(m, g)[source]

Bases: object

Class to store the ALP parameters

__init__(m, g)[source]

Initialize the ALP class

Parameters:

  • m (float) – ALP mass in neV.

  • g (float) – photon-ALP coupling in 10^-11 GeV^-1.

property g
property m
class gammaALPs.core.ModuleList(alp, source, pin=None, EGeV=None, seed=None, log_level='info')[source]

Bases: object

Class that collects all environments for photon-ALP mixing and manages common parameters such as photon-ALP coupling, the ALP mass, the source, and the energies at which the photon-ALP oscillation is computed.

property EGeV
__init__(alp, source, pin=None, EGeV=None, seed=None, log_level='info')[source]

Initialize the class, energy range, and polarization matrices

Parameters:

  • alp (ALP) – ALP object with ALP parameters

  • source (Source) – Source object with source parameters

  • pin (array-like) – 3x3 dim matrix with initial polarization. Default: un-polarized photon beam

  • EGeV (array-like) – n-dim numpy array with gamma-ray energies in GeV Default: log-spaced array between 1 GeV and 10 TeV

  • seed (int, optional) – Seed for RandomState for numpy random numbers. Must be convertible to 32 bit unsigned integers.

  • log_level (str) – level for logging, either ‘debug’, ‘info’, ‘warning’ or ‘error’

add_disp_abs(EGeV, r_kpc, disp, module_id, type_matrix='dispersion', **kwargs)[source]

Add dispersion, absorption, or extra momentum difference term to a propagation module using interpolation of of a 2d dispersion / absorption matrix

Parameters:

  • EGeV (array-like) – n-dim array with gamma-ray energies in GeV at which dispersion/absorption/momentum difference matrix is calculated

  • r_kpc (array-like) – m-dim array with distnaces in kpc at which dispersion/absorption/momentum difference matrix is calculated

  • disp (array-like) – n x m-dim array with dispersion (unitless) / absorption (in kpc^-1) / momentum difference (in kpc^-1)

  • module_id (int) – id of module to which dispersion / absorption /momentum difference is added

  • type_matrix (str) – either ‘dispersion’, ‘absorption’, or ‘Delta’, specifies type of matrix disp

add_propagation(environ, order, **kwargs)[source]

Add a propagation environment to the module list

Parameters:

  • environ (str) – identifier for environment, see notes for possibilities

  • order (int) – the order of the environment along the line of sight, starting at zero, where zero is closest to the source and highest value is closest to the observer

Notes

kwargs are passed to the specific environment.

Available environments are the classes given in environs, where all the specific options are listed. The identifiers for the environments are:

  • IGMF: initializes MixIGMFCell for mixing

    in intergalactic magnetic field (IGMF) which is assumed to be of a cell-like structure

  • ICMCell: initializes MixICMCell for mixing

    in intra-cluster medium which is assumed to be of a cell-like structure

  • ICMGaussTurb: initializes MixICMGaussTurb for mixing

    in intra-cluster medium which is assumed to follow a Gaussian turbulence spectrum

  • ICMStructured: initializes :py:class:`~gammaALPs.base.environs.MixICMStructured`for mixing

    in intra-cluster medium which is assumed to be structured with radial, poloidal and toroidal components, see 1008.5353 and 1908.03084

  • Jet: initializes MixJet for mixing

    in the AGN jet, where the field is assumed to be coherent

  • JetHelicalTangled: initializes MixJetHelicalTangled for mixing

    in the AGN jet with two field components (tangled and helical)

  • GMF: initializes MixGMF for mixing

    in the Galactic magnetic field (GMF) of the Milky Way

  • File: initializes MixFromFile for mixing

    in a magnetic field given by a data file

  • Array: initializes MixFromArray for mixing

    in a magnetic field given by a numpy arrays for B,psi,nel,r, and dL

  • EBL: initializes OptDepth for EBL attenuation,

    i.e. no photon-ALP mixing in the intergalactic medium

property alp
property modules
property pa
property pin
property px
property py
run(multiprocess=1)[source]

Run the photon-ALP conversion probability calculation for all modules

Parameters:

multiprocess (int) – number of cores to perform calculation; only used when random B field is requested by one of the modules and number of realizations is > 1

Returns:

Px, Py, Pa – N x M dim. arrays with final photon and ALP states (Px, Py, Pa). Each P_i is of dimension (number of realizations x number of energy bins). Flat arrays are returned when number of realizations = 1.

Return type:

tuple with numpy.ndarray

property seed
property source