Raquel Fraga-Encinas

RESEARCH TOPICS

I am interested in investigating the properties of Sagittarius A* (Sgr A*), the supermassive black hole at the center of our own galaxy. I study the physical mechanisms that result in emission at radio wavelengths (centimeter/millimeter), and the characteristics of the plasma at distances very close to this supermassive black hole.

It has been a long standing question in Astrophysics whether the radiation emitted by Sgr A* is generated by an accretion flow (hot material that forms an accretion disk as it falls onto the black hole) or by a relativistic jet. By studying the properties of Sgr A*, such as the geometry of the plasma, we can place constraints on the possible models responsible for the emission. I focus on two types of models: advection dominated accretion flows (ie. disks) versus mildly relativistic jets. I also investigate the effects of the interstellar scattering screen, located between us and the Galactic Center, which affects how Sgr A* appears on real observations.

Below is a simulation of 2 models of Sgr A* observed at 7mm. An accretion disk (left) and a jet model (right):

Credit: Fraga-Encinas, Moscibrodzka et al. 2019, in preparation.

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RESEARCH PROCESS

My work starts by coming up with research ideas with collaborators, then transforming those ideas into Physics problems and questions that need to be answered. The process continues by writing proposals for observations with different radio telescopes or by testing theoretical models. I do this by writing scripts to calibrate data from observations, and to simulate physical models that can be compared to that data, and then analyze the results. This process involves frequent iterations with colleagues to improve the methods of problem solving and checking that our results make physical sense. The final step is to share our findings in scientific conferences or peer-reviewed journal publications.