SRON

Visiting institute (TNA), X-rays

SRON is the Dutch national expertise institute for scientific space research. Our scientific focus points are low- and high-energy astrophysics, exoplanets and studies of the Earth’s atmosphere. In these scientific areas, we develop detection technologies and provide instruments and parts for ESA, NASA, and JAXA missions. As a national expertise institute, we stimulate collaboration between the science community, technological institutes, and industry. SRON has locations in Leiden and Groningen.

Main contact for TNA call: Jelle de Plaa

 

Available expertise

For the ACME visitor program, we offer expertise in X-ray astrophysics, especially in high-resolution X-ray spectroscopy. The high-energy astrophysics group has a long history in spectral modeling in X-rays and contributing to X-ray missions like XMM-Newton, Chandra, XRISM, and NewATHENA.

We aim to derive the best scientific results from X-ray spectra using our knowledge of the instruments and the physics of hot plasmas and dust. Having close connections with our instrument scientists and engineers helps us to understand instrumental issues which are sometimes overlooked. With our calibration expertise, we can make sure that the measurements are as accurate as possible.

SRON has a long history in developing models for X-ray emission and absorption. We have built models for thermal plasmas for stars and clusters of galaxies, non-equilibrium plasmas for supernova remnants, photo-ionized plasmas found in outflows from accretion disks around black holes, dust absorption in the ISM, and charge exchange on the interface between hot and cool gas. These models can be found in our SPEX software.

 

Available tools

The SPEX X-ray spectral fitting package is a software tool to fit X-ray spectra. It has been optimized for high-resolution spectroscopy and is very useful for grating spectra from XMM-Newton RGS, Chandra LETG/HETG, and micro-calorimeter spectra from Hitomi Resolve.

The development of spectral models began already in 1972 by Rolf Mewe, which lead to the MEKAL model in the 1980’s. From the 1990’s, Jelle Kaastra started developing a spectral fitting code in Fortran, which has been continuously expanded and maintained. SPEX contains a wide range of spectral models, which makes it ideal for fitting X-ray spectra from any astrophysical source, observed by any X-ray observatory. More recently, a Python interface was developed for the SPEX program, which makes it easier to script and include in Jupyter notebooks.

The main advantage of SPEX is that most of the plasma models use the same atomic database and the same routines calculating the spectral processes, making it consistent across models.

 

Involved scientists

Aurora Simionescu is specialized in the intra-cluster medium of clusters of galaxies from the cores to their outskirts. She studies how the heat is distributed in the cluster through the radio jets and lobes of the central supermassive black hole, how this process influences the distribution of metals, and how this leads to turbulence. Aurora also determines the gas properties in the faint outskirts of clusters, which requires accurate knowledge of the X-ray background.

Elisa Costantini studies the nature of the dust in the inter-stellar medium through X-ray spectroscopy. When the Galactic column density is high, XAFS in spectral absorption edges can give us clues about which molecules are present in the ISM. Elisa is building a database of molecular signatures using laboratory measurements. In addition, she works on outflows from accretion disks in X-ray binaries and Active Galactic Nuclei.

Jelle de Plaa is a scientific programmer and co-developer of the SPEX fitting package. With a history in cluster of galaxies research, he is an expert in X-ray data analysis and the software tools used.

Liyi Gu is an X-ray spectroscopist who develops and uses state-of-the-art spectral models. This includes calculating atomic data, and calculating the spectra for various plasmas, including charge exchange, photo-ionization, collisional ionization, and non-equilibrium situations. This applies to clusters, AGN, X-ray binaries, supernova remnants, comets and stars. He is the developer of the SPEX fitting package.