Foreground Data

Foreground: Modeling Codes

Below is a list and short description of publicly available codes to estimate Galactic foregrounds, with emphasis on diffuse emission at microwave frequencies. The left-most column provides a model name, followed by links to the code's location, the associated publication, and a table showing dependencies of each model on template maps, where applicable.

A list of tools that are useful for cleaning foregrounds from observations is also available.

Click on Name, Year or Simulates to sort by that column.

Foreground Models
Name Year Description Simulates
Global Sky Model (GSM)
Code, Python Code, ADS, Templates Used
2016. 2008 The GSM is a template-based model derived from a principal component analysis of radio and microwave survey data in total intensity only. It can be used to predict the total intensity emission from 10MHz to 5THz based on the four components found by the principal component analysis (PCA). The analysis assumes spectral dependence that is constant on the sky but unconstrained in frequency (i.e., not just power laws), and the resulting components approximately correspond to combinations of synchrotron, free-free, thermal dust and spinning dust emission.
The above is an update to the original version of the GSM discussed in de Oliveira-Costa et al.(2008)Code for the original implementation is here.
Code, ADS
2009 A C++ code for simulating polarized Galactic synchrotron and thermal dust emission as well as Faraday rotation measure (RM) based on physical, 3D models of Galactic magnetic fields, thermal electrons, cosmic ray leptons, and dust density. It uses a HEALPix-based grid refined with distance to integrate through a 3D Galaxy model to create full-sky simulations that take into account Faraday effects, realizations of random magnetic fields, and beam and depth depolarization. All included models have been constrained by comparison with various observations described in the literature. This is a physical modeling tool (rather than phenomenological, like the PSM) but it can also optionally combine the ?pure model? observables with intensity templates. It is modular to allow users to add their own field or particle models, either coded analytically or as gridded inputs. Its primary purpose is full-sky, physical modeling of the magnetized interstellar medium and informing methods of component separation by including realistic models of the fields, including the random fields, in 3D. IQU+
Herv√Ćas-Caimapo etal
Code, ADS, Templates Used
2016 A template-based Python code for modeling diffuse, polarized synchrotron and thermal dust emission. This tool uses the Planck foreground products for synchrotron and dust emission, parametrized and spatially varying spectral models (e.g., power laws with curvature) in order to produce simulations of the sky at any frequency. This tool includes the option to add constrained realizations of stochastic (Gaussian) components at small scales. It can also include a polarized emission component from anomalous microwave emission (AME). It includes the ability to observe the modeled sky with a theoretical instrument with a given bandpass, beam, and noise sensitivity. It is meant to be simpler and more flexible than the PSM, and it is also primarily intended for providing simulated inputs for, e.g., planning future CMB missions. IQU
Low Frequency Sky Model
Code, ADS, Templates Used
2017 The Low Frequency Sky Model (LFSM) is an updated model of the radio sky between 10 and 408 MHz. The model builds off the analysis approach used for the Global Sky Model of de Oliveira-Costa et al. (2008). It is based on a principal component analysis of data at 10, 22, 40, 45, 50, 60, 70, 80, 408, 819, 1419, 23000, 33000, 41000, 61000, and 94000 MHz. I
Planck Sky Model (PSM)
Code, ADS, Templates Used
2014 A template-based tool that represents the pre-Planck knowledge of the sky from GHz-THz frequencies in intensity and polarization based on multi-wavelength full-sky observations.. Its modeled emission components include the CMB, synchrotron, thermal dust, free-free, CO, SZ, point sources, CIB, and UCHII regions. The input templates are normalized and extrapolated following parametrized and spatially varying spectral models (e.g., power laws with curvature) in order to produce simulations of the sky at any frequency. This tool includes the option to add small scale structure from constrained realizations of stochastic (Gaussian) components for the CMB, SZ, point sources, synchrotron and dust emission. It also includes the ability to observe the modeled sky with a theoretical instrument with a given bandpass, beam, and noise sensitivity. This code is primarily intended to provide simulated inputs for testing mission mapmaking pipelines, testing component separation algorithms, or planning future CMB missions. IQU
Python Sky Model (PySM)
Code, ADS, Templates Used
2016 Python code to simulate maps of Galactic emission in intensity and polarization at microwave frequencies (10-500 GHz) based on data templates from Haslam 408 MHz, WMAP and Planck surveys. Synchrotron, thermal dust, free-free, and anomalous microwave emission components may be simulated over the whole sky, in addition to the Cosmic Microwave Background. Empirical forms are used to describe the frequency dependence of each component, with options for alternative forms. Capability to include instrumental response and noise is included at a basic level. A prescription is provided for adding small-scale realizations of these components on spatial scales less than roughly 1 degree. IQU
Meisner & Finkbeiner
Code, ADS, Templates Used
2015 Model predictions of Galactic thermal dust total intensity emission at 6.1 arcmin resolution from 100 GHz to 3000 GHz, based on a parameterization of the dust spectrum derived from Planck, DIRBE and IRAS data as the sum of two modified black bodies. The method serves as an alternative to single component modified black body models. Dust optical depth and temperature maps are also available. The original analysis based on FIRAS, DIRBE and IRAS data is described by Finkbeiner etal 1999 I
Code, ADS
2014 A Bayesian component separation tool that includes template-based, physical foreground modeling for any parametrized total and polarized intensity components. This tool is flexible enough to allow for different spectral shapes, varying spectral parameters across the sky, and any foreground component that can be defined as a linear combination of templates in intensity and polarization. Note that it simultaneously solves for the CMB component. IQU
2018 Commander3 is the public release of the most recent version of Commander (Commander is an Optimal Monte-carlo Markov chAiN Driven EstimatoR) code for fast and efficient end-to-end CMB posterior exploration through Gibbs sampling. IQU
DIRBE Zodi Model
Code, ADS
1998 IDL code for calculating the Kelsall/etal:1998 zodiacal light model for DIRBE bands between 1.2 and 240 um using parameterized functional forms for the geometry of the main cloud, bands and earth orbit 'blobs' emissivity and scattering functions. I
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