The Brazilian astronomer is the third graduate of the program taught by the Institute of Astrophysical Studies at Diego Portales University.
22 / 12 / 2023
“The Structure and Dynamics of the Interstellar Medium in Galaxies of the Early Universe”, is the title of Ana Posses’ thesis, whose supervisors were Manuel Aravena (UDP full professor) and Jorge González (Carnegie/UDP postdoctoral researcher), and whose main objective was to investigate the morphology, dynamics, and how gas is moving within early galaxies, in addition to comparing them with already known galaxies.
Ana’s doctoral thesis will contribute to our understanding of the field of galactic astrophysics, and therefore last Friday, December 1, she became the third graduate of the program taught by the Institute of Astrophysical Studies UDP.
The work of Ana Posses – who also maintains a master’s degree in astronomy from the National Observatory of Brazil – is divided into two scientific articles, one of them already published and the other in the process of being sent to a peer-review journal. The first publication focuses on a very distant and early galaxy, (when the universe was just 6% of its current age), where the dynamics and the structure of the galaxy were studied. “What was discovered is that this galaxy had moving gas, and that it is very possibly rotating and forming a disk, but clearly more observations are needed to confirm that finding. Furthermore, there are indications that there could be gas falling into the galaxy from the surrounding area,” explains Professor Aravena.
The second publication, still in preparation, extends this work on another early galaxy, this time when the universe was 7% of its current age. In this case, the data comes from a large-scale program carried out at the ALMA observatory called CRISTAL – led by professors Rodrigo Herrera (UDEC), Manuel Aravena and Jorge González (UDP) – which provides detailed data and observations that allow for a much deeper analysis, more detailed than could be done on other objects.
“This case is a little more complex; the galaxy we are studying is made up of two galaxies that are merging. Within that merger, one of the galaxies shows signs of rotation in a disk. However, given the interaction with the other galaxy, the disk is being disturbed. In addition, there are also possible signs of more extended gas outside the galaxy, which could be an indication of gas that is infalling or leaving the galaxy, what we call feedback; gas expelled by the creation of stars. Given the compactness of this fusion, we can only witness this complex system due to the high fidelity of the data obtained with ALMA,” Posses elaborates.
It is worth mentioning that Dr. Posses was recently awarded a program with ALMA as principal investigator, to obtain even deeper observations and to delve into the discoveries made in her first publication. In this project she obtained observations equivalent to 24 hours of observation time with ALMA.
After successfully defending her thesis, Ana Posses becomes the third graduate of the UDP Doctorate program in Astrophysics, after Dejene Zewdie, who obtained the degree in October; and Kriti Gupta, who got it in May this year.