The upcoming launch of NASA's Compton Spectrometer and Imager (COSI) marks a significant milestone in our quest to unravel the mysteries of gamma-ray physics. With its planned launch in August 2027, COSI promises to revolutionize our understanding of the universe by probing the soft-gamma ray regime, an understudied portion of the electromagnetic spectrum. This cutting-edge observatory will observe in the 0.2-5 MeV frequency range, offering a unique perspective on various cosmic phenomena.
In a recent study, authors Falk Herwig, Pavel Denissenkov, and Eric Burns delve into the capabilities of COSI in detecting the intermediate neutron capture process (i-process). This process, often overlooked in astronomy classes, plays a crucial role in the formation of elements beyond iron on the periodic table. The i-process occurs in post-asymptotic giant branch stars (post-AGBs) and rapidly-accreting white dwarfs (RAWDs), creating unique isotopes that differ from those produced by the s-process and r-process.
The challenge lies in identifying stars that have undergone the i-process. Astronomers look for high abundances of rubidium, strontium, yttrium, and zirconium against a reference star. To assess COSI's potential, the authors estimated the upper limit of abundances for a single i-process event. By comparing the photon flux of seven i-process emission lines to COSI's sensitivity, they concluded that three-sigma detections would be faint but resolvable.
This research highlights the importance of COSI in advancing our knowledge of gamma-ray physics and the i-process. As we eagerly await its launch, astronomers worldwide are conducting tests to push the boundaries of its capabilities. COSI's ability to detect the i-process will not only enhance our understanding of stellar evolution but also contribute to the broader field of astrophysics, shedding light on the origin of high-energy particles within and beyond our galaxy.
