Centre for Astro-Particle Physics
As the name suggests the Centre is focused on cross-disciplinary research with topics from Astrophysics and Particle Physics. Information from various corners of the universe reaches us in the form of light, which behaves like a particle at high energies and called gamma rays, and in the form of other elementary particles such as cosmic rays and neutrinos. These particles are produced in the fantastic laboratories in the universe, such as black holes of various masses, neutron stars, exploding stars, etc., which far exceed the efficiencies of even the largest man-made laboratories. The research at CAPP is aimed at studying these particles from nature and advance our understanding of various astrophysical sources of these particles as well as to use these particles to answer some of the most fundamental physics questions.
Researchers at CAPP are involved in theoretical modelling, computation and data analysis. Some of the astrophysical sources that are studied closely are Gamma-ray bursts (GRBs) and Active-galactic nuclei (AGNs). Gamma-ray bursts are the most luminous explosions in the universe, arising either from the death of a rare type of massive star or from the mergers of binary systems (neutron star-neutron star or neutron star-black hole). GRBs can be detected in galaxies out to the edge of the visible universe. Active-galactic nuclei are a subclass of galaxies with a supermassive black hole (with 10 to over 100 million times the mass of the Sun) at its centre that is devouring materials from its surrounding and throwing them in narrow jets with speed close to the speed of light. Gamma rays from AGNs have been detected that have energies exceeding the maximum energy achievable at the Large Hadron Collider (LHC), the most powerful man-made particle accelerator.
Artist's concept of a GRB (Credit: NASA / Swift / Cruz deWilde)
The most energetic particles in nature are cosmic rays, detected with energies up to billions of trillion (1021) electron Volt. It is a mystery how and where exactly these particles are created in nature. Cosmic rays are charged particles and they interact with other particles and radiation fields to produce secondary particles including very high energy gamma rays and neutrinos. These gamma rays are now routinely detected on the earth and from space. Cosmic rays hitting the atmosphere of the earth produce neutrinos that have been measured with good accuracy. Questions in fundamental Physics such as neutrino mass, charge-parity violation and extra species are being addressed using these atmospheric neutrinos. Recently Peta (1015) electron Volt neutrinos have been detected directly from astrophysical sources. Researchers at CAPP model acceleration, interactions and propagation of energetic cosmic rays, neutrinos and gamma rays from various plausible astrophysical sources in our Galaxy and in other galaxies. Very recently gravitational waves, predicted by Einstein, have been detected from merging of binary black holes and neutron stars. Members of CAPP are embarking on research in this area as well.
Over 400 years ago Galileo looked through his telescope and started modern Astronomy. Visible light was the only way to study the universe for the next 300 or so years until cosmic rays were discovered in 1912 by Victor Hess. We are now in an era of true multi-messenger Astronomy with discovery of high-energy cosmic neutrinos and gravitational waves only during this decade. This certainly means that researchers at CAPP will be busy studying the universe with these cosmic messengers in foreseeable future.
Professor of Physics and Director of CAPP
"Shoot for the moon. Even if you miss it you will land among the stars." - Les Brown