The upcoming launch of NASA's Compton Spectrometer and Imager (COSI) has astronomers worldwide eagerly awaiting its arrival. This new gamma-ray observatory, set to lift off in August 2027, promises to revolutionize our understanding of modern physics by probing the understudied soft-gamma ray regime (0.2-5 MeV). But what makes COSI particularly exciting is its potential to detect the elusive i-process, a secret third kind of neutron capture that occurs in the aftermath of post-asymptotic giant branch stars and rapidly-accreting white dwarfs.
Many astronomy students are familiar with the s-process and r-process, but the i-process remains a hidden gem. It produces unique isotopes that are difficult to distinguish from those created by the s- and r-processes. To identify the i-process, astronomers look for high abundances of rubidium, strontium, yttrium, and zirconium in stars, but the challenge lies in determining the upper limit of these abundances for a single i-process event.
In this context, the authors of the paper sought to numerically determine COSI's ability to detect the i-process. By comparing the photon flux of seven i-process emission lines to COSI's sensitivity, they found that three-sigma detections would be faint but resolvable. This means that COSI could potentially uncover the secrets of the i-process, providing valuable insights into the origin of high-energy particles within our galaxy and beyond.
What makes this discovery particularly fascinating is the potential for multiple i-process events within the same star without complete destruction. This raises a deeper question: how can we better understand and detect these rare processes? The answer lies in the capabilities of COSI and the dedication of astronomers worldwide who are eager to explore the unknown.
In my opinion, the launch of COSI marks a significant milestone in our quest to understand the universe. It represents a step forward in our ability to probe the soft-gamma ray regime and uncover the mysteries of the i-process. As we prepare for liftoff, let us embrace the excitement and anticipation of what lies ahead, knowing that the secrets of the cosmos are within our reach.
