Young CATA astronomer has advanced the modeling of information ranging from the radio spectrum to X-rays to more accurately analyze galaxies and supermassive black holes.
Researcher Laura Martínez-Ramírez has developed an evolved version of an existing code, which she called AGNFITTER-RX. It is an advanced tool for modeling the spectral energy distribution of active galaxies (AGN), covering from the radio spectrum to X-rays. This model includes key components of active galaxy nuclei, such as the accretion disk, the hot dust torus, relativistic jets and the hot corona. It also considers the contribution of host galaxies, such as stellar populations and cold dust.
This new code allows us to unravel the physical properties of AGNs and their host galaxies, such as the mass of supermassive black holes, star formation rates and torus inclination angles. This has applications in studies of galaxy evolution, black hole feedback, and the physical processes that produce radiation at different wavelengths. The tool is crucial for future research with data from advanced observatories such as the James Webb Space Telescope (JWST) and the Square Kilometre Array (SKA).
This was based on the analysis of 36 nearby active galaxies, with a compilation of up to 49 photometric data per object from different telescopes. Laura Martínez-Ramírez is an Associate Astronomer at the Centro de Astrofísica y Tecnologías Afines, CATA, and a PhD student at the Universidad Católica, the University of Heidelberg and the Max-Planck-Institut für Astronomie. She also had the collaboration of CATA’s Associate Researcher, Franz Bauer, also a professor at the Catholic University.
AGNFITTER-RX integrates state-of-the-art theoretical and semi-empirical models and uses Bayesian methods to explore complex parameter spaces. The code allows customization of models and filters to suit various scientific objectives and data availability. In addition, it offers flexibility to include new observations in the radio and X-ray bands, which has traditionally been a challenge in this field.
“The importance of this code being photometric points to the fact that it is a factor that is quickly released in public catalogs and makes it easier to obtain, because spectra are already a bit more complicated and require more expensive instruments. If someone wanted to start a new project, they simply need to collect photometric data from different surveys, create their catalog of the objects they want to study, use my code and obtain physical estimates of some properties,” explained Laura Martínez-Ramírez.
In this sense, the CATA astronomer added that they included in the code different models that are motivated by observations and that allowed them to demonstrate the relevance of the emission lines in the quality of the adjustment and the information obtained.
“Our models find or estimate a black hole mass that is comparable with estimates based on spectra that are much more precise and we find that the values are comparable for most objects. So, for example, if we find an interesting object and we don’t have the ability to get a fast spectrum, we could use my code to make an estimate of how much the mass of the black hole might be and then if you can get the spectrum, compare. But, at least, as a first estimation it is very good”, detailed Laura.
Regarding CATA’s contribution to the process, the astronomer emphasized that it was very relevant, since it allowed her access to a large community of scientists with whom to share her results, have a debate and obtain feedback that guided her in the direction of her research.
In addition, the study demonstrated that clumpy torus models with polar winds (such as CAT3D) and accretion disks with emission line features significantly improve the quality of the fits. However, challenges remain in modeling certain bands such as the near-infrared.
The tool is publicly available, available in Python, and is designed to integrate with future advanced photometric surveys.
The study, which is part of the first part of Laura Martínez-Ramírez’s PhD thesis, was published as a paper in Astronomy & Astrophysics.