zodipy 0.1.5

Zodipy is a python tool that simulates the instantaneous Zodiacal emission as seen from an observer.

Zodipy

Description

Zodipy is a python tool that simulates the instantaneous Zodiacal emission as seen by an observer.

Installing

Zodipy is installed with pip.

pip install zodipy

Examples

The following examples provides an overview of how Zodipy may be used to produce various simulations of the Zodiacal emission.

Simulating a single observation

The simplest use case of Zodipy is to simulate the instantaneous emission as seen from the Earth-Sun Lagrange point 2, as of today (This is the default behavior of the Zodi object):

import zodipy

zodi = zodipy.Zodi()
emission = zodi.get_emission(nside=128, freq=800)

We started by initializing the Zodi object with default arguments, after which we have called the get_emission method of the Zodi object, which simulates the emission at a given map resolution (nside) and frequency.

We can visualize the emission using Healpy:

Alternatively, a specific observer, and a date (datetime object) can be passed as arguments to the Zodi object, which initializes the new configuration:

import zodipy
from datetime import datetime

zodi = zodipy.Zodi('Planck', datetime(2010, 1, 1))
emission = zodi.get_emission(nside=128, freq=800)

It is possible to return the Zodiacal emission component-wise by setting the keyword return_comps in the get_emission function to True.

Masked observations

We can specify the angle between the observer and the Sun for which all pixels are masked out. This is done in the get_emission function by providing the keyword argument solar_cut, which takes in an angle. In the following we attempt to mimic typical satellite scanning strategies by masking out all pixels that look inwards towards the Sun:

import zodipy
from datetime import datetime

zodi = zodipy.Zodi('Planck', datetime(2010, 1, 1))
emission = zodi.get_emission(nside=128, freq=800, solar_cut=90)

Simulating the mean over multiple observations

We can simulate the mean emission over a set of observations by initializing the Zodi object with the following keywords:

import zodipy
from datetime import datetime

zodi = zodipy.Zodi(
    observer='Planck', 
    start=datetime(2010, 1, 1), 
    stop=datetime(2011, 1, 1), 
    step='10d'
)
emission = zodi.get_emission(nside=128, freq=800, solar_cut=90)

Here we take the mean of linearly spaced observations from 2010-01-01 to 2011-01-01 with a step size of 10 days (note that this is a more expensive operation and may take up to a few minutes depending on the map resolution and number of observations).

Interplanetary dust models

Zodipy uses the Kelsall et al. (1998) Interplanetary dust model. The line-of-sight integrals are computed using the definition in Planck 2013 results. XIV. Zodiacal emission. During the Planck analysis, three different sets of emissivities were fit to describe the emission. These can be selected by providing the keyword argument model to the Zodi object:

import zodipy

zodi = zodipy.Zodi(model='planck 2013')

The available models are 'planck 2013', 'planck 2015', and 'planck 2018'. The default is the 2018 model. Note that selecting the 2013 model will include the Circumsolar and Earth-trailing components, which were left out in the 2015 and 2018 Planck analyses.