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News

November 2019: APEC model revised

Interpolation issues have been discovered in the APEC model. The exact effects of these vary significantly depending on the exact plasma being analyzed and the instrument in use. More details.

November 2019: Kappa and Electron-Electron Bremsstrahlung Model released

Models for non-Maxwellian electrons, and e- - e- collisions, created by Xiaohong Cui, are now available. These include models for including them in XSPEC.

October 2019: ACX2 updated model released

A minor update has been made to the ACX2 model to correct an indexing error in the vvacx model

October 2019: ACX 1.0.2 model released

We have updated the AtomDB Charge eXchange model to work with HEASOFT 6.24.

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Project Quick Links

There are several different sub-projects under the AtomDB umbrella. These are:


What is AtomDB?

AtomDB is an atomic database designed for X-ray plasma spectral modeling. The current version of AtomDB is primarly used for modeling collisional plasmas, those where hot electrons colliding with astrophysically abundant elements and ions create X-ray emission. However, AtomDB is also useful when modeling absorption by elements and ions or even photoionized plasmas, where X-ray photons (often from a simple power-law source) interacting with elements and ions create complex spectra.

Our goal is to incorporate not only all relevant data, generated both from theoretical models and experiment, but also to critically evaluate this data to create recommended models. Each revision of the critically evaluated database is given a version number to aid reference.

The current release is version 3.0.9. Please see the the release notes on the download page for more details.

For interactive line lists and data, we provide the AtomDB WebGUIDE and an iPad app.


AtomDB provides improved spectral modeling capability through additional emission lines, accurate wavelengths for most strong X-ray transitions, and new density-dependent calculations. While many of the improvements are directed toward X-ray grating data analysis, some differences between AtomDB and other models might be noticeable even at moderate (CCD) resolution.

The atomic database AtomDB includes the Astrophysical Plasma Emission Database (APED) and the spectral models output from the Astrophysical Plasma Emission Code (APEC). The APED files contain information such as wavelengths, radiative transition rates, and electron collisional excitation rate coefficients. APEC uses these data to calculate plasma model spectra. The APEC output models in AtomDB are for optically-thin plasmas in collisional ionization equilibrium. APEC outputs separate continuum and line emissivity files, making it easy to model continuum and line emission separately as well as together.

The AtomDB is used by Sherpa, GUIDE and ISIS to identify emission lines and to calculate spectra for comparison with observations. All the files in the AtomDB are in FITS format, and can be easily read using the CIAO's Prism.

If you use these models, please register so we can notify you when updates or corrections are made.

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