Issue |
A&A
Volume 695, March 2025
|
|
---|---|---|
Article Number | A190 | |
Number of page(s) | 6 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/202451915 | |
Published online | 19 March 2025 |
The aluminium-26 distribution in a cosmological simulation of a Milky Way-type Galaxy
1
Institute of Theoretical Physics, University of Wrocław,
50-204
Wrocław,
Poland
2
Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences,
Konkoly Thege Miklós út 15-17.
1121,
Hungary
3
CSFK, MTA Centre of Excellence,
Budapest,
Konkoly Thege Miklós út 15-17.
1121,
Hungary
4
Centre for Astrophysics Research, University of Hertfordshire,
College Lane,
Hatfield
AL10 9AB,
UK
5
Computer, Computational and Statistical Sciences (CCS) Division, Center for Theoretical Astrophysics, Los Alamos National Laboratory,
Los Alamos,
NM
87545,
USA
6
ELTE Eötvös Loránd University, Institute of Physics and Astronomy,
Budapest
1117,
Pázmány Péter sétány 1/A,
Hungary
7
School of Physics and Astronomy, Monash University,
VIC 3800,
Australia
★ Corresponding author; benjamin.wehmeyer@uwr.edu.pl
Received:
18
August
2024
Accepted:
23
February
2025
Context. The 1.8 MeV γ-rays corresponding to the decay of the radioactive isotope 26Al (with a half-life of 0.72 Myr ) have been observed by the SPI detector on the INTEGRAL spacecraft and extensively used as a tracer of star formation and current nucleosynthetic activity in the Milky Way Galaxy. Further information is encoded in the observation related to the higher 26Al content found in regions of the Galaxy with the highest line-of-sight (LoS) velocity relative to an observer located in the Solar System. However, this feature remains unexplained.
Aims. We ran a cosmological “zoom-in” chemodynamical simulation of a Milky Way-type galaxy, including the production and decays of radioactive nuclei in a fully self-consistent way. We then analyzed the results to follow the evolution of 26Al throughout the lifetime of the simulated galaxy to provide a new method for interpreting the 26Al observations.
Methods. We included the massive star sources of 26Al in the Galaxy and its radioactive decay into a state-of-the-art galactic chemical evolution model, coupled with cosmological growth and hydrodynamics. This approach allowed us to follow the spatial and temporal evolution of the 26Al content in the simulated galaxy.
Results. Our results are in agreement with the observations with respect to the fact that gas particles in the simulation with relatively higher 26Al content also have the highest LoS velocities. On the other hand, gas particles with relatively lower 26Al content (i.e., not bright enough to be observed) generally display the lowest LoS velocities. However, this result is not conclusive because the overall rotational velocity of our simulated galaxy is higher than that observed for cold CO gas in the Milky Way Galaxy. Furthermore, we found no significant correlation between gas temperature, rotational velocity, and 26Al content at any given radius. We also found the presence of transient 26Al-rich spots at low LoS velocities and we show that one such spot had been captured by the INTEGRAL/SPI data. Based on our model, we present a prediction for the detection of 1.8 MeV γ-rays by the future COSI mission. We find that according to our model, the new instrument will be able to observe similar 26Al-emission patterns to those seen by INTEGRAL/SPI.
Key words: ISM: abundances / evolution / ISM: kinematics and dynamics / Galaxy: abundances / Galaxy: evolution
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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