Bangalore: In a groundbreaking development, scientists at the Raman Research Institute (RRI), an autonomous institute under the Department of Science and Technology (DST), have unveiled a new approach to explore Cold Dark Matter (CDM), a mysterious component that constitutes 25 percent of the current Universe.
In the present cosmos, dark energy makes up nearly 70 percent, and dark matter accounts for 25 percent—both of which remain enigmatic. Understanding the nature of dark matter and its interactions with the rest of the universe has been a longstanding challenge. Until now, scientists have only been able to study a small fraction of the Universe, making it difficult to discern the constituents of cold dark matter.
The confusion is further compounded by the discrepancy between two models used to study CDM: the particle physics model and the cosmological model. While the cosmological model provides insights into the largest-scale structures and dynamics of the universe, the particle physics model delves into the most fundamental building blocks.
One of the leading candidates for CDM is Weakly Interacting Massive Particles (WIMP), a particle that naturally emerges in extensions of the standard model of particle physics. Despite extensive searches and improvements in lab experiment sensitivity, such as Xenon-based experiments, WIMPs have eluded detection.
In a recently published paper, Professor Shiv Sethi from RRI, along with collaborator Abineet Parichha, presented a novel approach to validate the relevance of WIMPs by relaxing earlier assumptions about particle stability. They demonstrated that an unstable WIMP, where one of its decay products acts as cold dark matter at later stages, satisfies all existing observational and experimental constraints.
“We considered a model wherein the WIMP decays, and one of the decay products acts as cold dark matter at late times. This scenario allows us to expand the permissible space of parameters and leaves observable signatures on the Cosmic Microwave Background and high redshift neutral hydrogen data,” explained Prof. Sethi, senior faculty of Astronomy and Astrophysics at RRI.
The findings challenge the assumption of a massive, stable WIMP and propose viable scenarios that suggest compatibility between the standard models of particle physics and cosmology. Moreover, the research hints at exciting possibilities in the dark matter sector, with data from the James Webb Space Telescope possibly offering more insights into this cosmic mystery.