Astrophysical source population models (gammapy.astro.population)

Introduction

The gammapy.astro.population module provides a simple framework for population synthesis of gamma-ray sources, which is useful in the context of surveys and population studies.

Getting Started

The following example illustrates how to simulate a basic catalog including a spiral arm model.

import astropy.units as u
from gammapy.astro.population import make_base_catalog_galactic

max_age = 1E6 * u.yr
SN_rate = 3. / (100. * u.yr)
n_sources = int(max_age * SN_rate)
table = make_base_catalog_galactic(
    n_sources=n_sources,
    rad_dis='L06',
    vel_dis='F06B',
    max_age=max_age,
    spiralarms=True,
)

The total number of sources is determined assuming a maximum age and a supernova rate. The table returned is an instance of Table which can be used for further processing. The example population with spiral-arms is illustrated in the following plot.

(png, hires.png, pdf)

../../_images/plot_spiral_arms.png

Galactocentric spatial distributions

Here is a comparison plot of all available radial distribution functions of the surface density of pulsars and related objects used in literature:

(png, hires.png, pdf)

../../_images/plot_radial_distributions.png

TODO: add illustration of Galactocentric z-distribution model and combined (r, z) distribution for the Besancon model.

Spiral arm models

Two spiral arm models of the Milky way are available: ValleeSpiral and gammapy.astro.population.FaucherSpiral

(png, hires.png, pdf)

../../_images/plot_spiral_arm_models.png

Velocity distributions

Here is a comparison plot of all available velocity distribution functions:

(png, hires.png, pdf)

../../_images/plot_velocity_distributions.png

Reference/API

gammapy.astro.population Package

Astrophysical population models.

Functions

add_observed_parameters(table[, obs_pos])

Add observable parameters (such as sky position or distance).

add_observed_source_parameters(table)

Add observed source parameters to the table.

add_pulsar_parameters(table[, B_mean, …])

Add pulsar parameters to the table.

add_pwn_parameters(table)

Add PWN parameters to the table.

add_snr_parameters(table)

Add SNR parameters to the table.

make_base_catalog_galactic(n_sources[, …])

Make a catalog of Galactic sources, with basic source parameters.

make_catalog_random_positions_cube([size, …])

Make a catalog of sources randomly distributed on a line, square or cube.

make_catalog_random_positions_sphere(size[, …])

Sample random source locations in a sphere.

Classes

CaseBattacharya1998([amplitude, alpha, beta])

Radial distribution of the surface density of supernova remnants in the galaxy - Case & Battacharya 1998.

Exponential([amplitude, z_0])

Exponential distribution.

FaucherKaspi2006([amplitude, r_0, sigma])

Radial distribution of the birth surface density of pulsars in the galaxy - Faucher-Giguere & Kaspi 2006.

FaucherKaspi2006VelocityBimodal([amplitude, …])

Bimodal pulsar velocity distribution - Faucher & Kaspi (2006).

FaucherKaspi2006VelocityMaxwellian([…])

Maxwellian pulsar velocity distribution.

FaucherSpiral

Milky way spiral arm used in Faucher et al (2006).

LogSpiral

Logarithmic spiral.

Lorimer2006([amplitude, B, C])

Radial distribution of the surface density of pulsars in the galaxy - Lorimer 2006.

Paczynski1990([amplitude, r_exp])

Radial distribution of the birth surface density of neutron stars - Paczynski 1990.

Paczynski1990Velocity([amplitude, v_0])

Distribution by Lyne 1982 and adopted by Paczynski and Faucher.

ValleeSpiral()

Milky way spiral arm model from Vallee (2008).

YusifovKucuk2004([amplitude, a, b, r_1])

Radial distribution of the surface density of pulsars in the galaxy - Yusifov & Kucuk 2004.

YusifovKucuk2004B([amplitude, a, b])

Radial distribution of the surface density of OB stars in the galaxy - Yusifov & Kucuk 2004.