The Evolutionary spectrum inversion and analysis (Especia) file set provides ISO C++ code for the inverse modelling and analysis of intergalactic and interstellar absorption line regions seen in QSO spectra.
Due to the use of evolution strategies with covariance matrix adaption, the inverse modelling procedure is highly competitive and capable of calculating the optimal spectral decomposition without requiring any particular initialisation.
Additional highlights are the joint modelling and optimisation of the background continuum, and an accurate semi-analytic convolution of the absorption term with the instrumental function. The method is explained in detail by Quast et al. (2005).
Especia enables you to analyse spectroscopic data. Though it has been developed for the analysis of astrophysical spectra, it is, in principle, applicable to spectroscopy in general. Read the notes and articles listed below to find out whether this software is of interest to you.
If you already have some understanding of these matters, you may want to consult the especia wiki before you clone the source code repository or download a release version.
Building Especia requires CMake and a compiler that implements C++11. For additional information on prerequisites consult the build instructions. Especia runs on various variants of macOS (including Big Sur on Intel and M1 machines) and Linux.
To build and test the Especia software cd into the project root directory and type:
mkdir cmake-build-release
cd cmake-build-release
cmake -DCMAKE_BUILD_TYPE=Release ..
make all test
Typing make install will complete the build and move the executable files into your
$HOME/bin directory.
Release versions YYYY.N are numbered by the year of the release followed by a single-digit number, which enumerates the release within the release year. For example, version 2024.1 denotes the first release of the year 2024. The latest release version is 2024.2
Quast, Ralf; Baade, Robert; Reimers, Dieter (2005). Evolution strategies applied to the problem of line profile decomposition in QSO spectra. Astronomy and Astrophysics 431 (3) 1167. DOI 10.1051/0004-6361:20041601.
Quast, Ralf (2017). Evolution strategies applied to the problem of line profile decomposition in QSO spectra. Zenodo. DOI 10.5281/zenodo.785424.
Quast, Ralf (2017). Covariance matrix adaption in evolution strategies. Zenodo. DOI 10.5281/zenodo.784203.