In the realm of astrophysics and energy research, a team of scientists from the Indian Institute of Technology Indore has been delving into the mysteries of microquasars, shedding light on their potential implications for our understanding of cosmic particle acceleration and the diffuse galactic emission. The researchers, Basanti Paul, Abhijit Roy, Jagdish C. Joshi, and Debanjan Bose, have recently published their findings in a study that explores the hadronic emissions from microquasars V4641 Sgr and SS 433.
Microquasars are fascinating binary systems in our galaxy, consisting of a star and a compact object like a neutron star or a black hole. These systems are known for their relativistic jets, which are streams of particles ejected at near-light speeds. Recent detections of very-high-energy and ultra-high-energy gamma-rays from these microquasars by advanced observatories like LHAASO, HAWC, and HESS have sparked interest in their role as Galactic PeVatrons, which are cosmic particle accelerators capable of reaching energies up to a few PeV (peta-electronvolts).
The researchers focused on the hadronic scenario, where gamma-rays are produced by the interaction of relativistic protons in the microquasar jet with the stellar wind. By fitting their model with observed data, they were able to constrain several physical parameters, including the hadronic jet power fraction, the proton spectral index, the maximum proton energy, and the jet bulk Lorentz factor. Their best-fit model revealed hard proton spectra and maximum proton energies ranging from 1 to 5 PeV.
One of the significant findings of this study is the potential for microquasars to be detected by next-generation neutrino telescopes like KM3NeT-ARCA and TRIDENT. The researchers estimated the all-flavor neutrino fluxes corresponding to the gamma-ray fluxes from the hadronic model and found that V4641 Sgr could indeed be detected by these advanced instruments.
Furthermore, the team modeled a synthetic population of Galactic microquasars to estimate their contribution to the diffuse TeV-PeV gamma-ray flux. They discovered that for the inner Galaxy, pulsars dominate the contribution in the range of 10-100 TeV, while above 100 TeV, diffused cosmic ray interactions with molecular clouds are most dominant. Interestingly, they found that a population of approximately 14 microquasars is required to explain the LHAASO data above 100 TeV. For the outer Galaxy, microquasars emerge as the dominant class of sources, with their population constrained to around 14.
The practical applications of this research for the energy sector are multifaceted. Understanding the mechanisms of particle acceleration in microquasars can provide insights into similar processes that occur in fusion reactors and other high-energy environments. Additionally, the detection of neutrinos from these cosmic sources can enhance our capabilities in neutrino astronomy, which has potential applications in monitoring and safeguarding nuclear reactors and other energy facilities.
In conclusion, the work of Basanti Paul and her colleagues at the Indian Institute of Technology Indore offers a compelling look into the world of microquasars and their role as Galactic PeVatrons. Their findings not only advance our understanding of cosmic particle acceleration but also open up new avenues for research in the energy sector. The study was published in the Astrophysical Journal, a prestigious journal in the field of astrophysics.
This article is based on research available at arXiv.