The aluminium-26 distribution in a cosmological simulation of a Milky Way-type Galaxy

Abstract

Context. The 1.8 MeV gamma-rays corresponding to the decay of the radioactive isotope Al-26 (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 Al-26 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 Al-26 throughout the lifetime of the simulated galaxy to provide a new method for interpreting the Al-26 observations. Methods. We included the massive star sources of Al-26 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 Al-26 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 Al-26 content also have the highest LoS velocities. On the other hand, gas particles with relatively lower Al-26 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 Al-26 content at any given radius. We also [...]

6 pages, 5 figures

References in corpus (14)

• The nucleosynthesis of Al26 and Fe60 in solar metallicity stars extending in mass from 11 to 120 Msun: the hydrostatic and explosive contributions
• Simulations of Cosmic Chemical Enrichment
• The Blueshifting and Baldwin effects for the [OIII] 5007 Emission Line in Type 1 Active Galactic Nuclei
• Stellar origin of the 182Hf cosmochronometer and the presolar history of solar system matter
• The Star Formation Rate of the Milky Way as seen by Herschel
• Stellar migrations and metal flows -- Chemical evolution of the thin disc of a simulated Milky Way analogous galaxy
• Spectral and intensity variations of Galactic 26^Al emission
• The Galactic ${}^{26}$Al emission map as revealed by INTEGRAL/SPI
• Comparing simulated ${}^{26}$Al maps to gamma-ray measurements
• Galactic 26Al traces metal loss through hot chimneys
• Synthetic ${}^{26}$Al emission from galactic-scale superbubble simulations
• Distribution and kinematics of 26Al in the Galactic disc
• Inhomogeneous enrichment of radioactive nuclei in the Galaxy: Deposition of live Mn-53, Fe-60, Hf-182, and Pu-244 into deep-sea archives. Surfing the wave?
• Chemical evolution of ${}^{26}$Al and ${}^{60}$Fe in the Milky Way