The universe is awash in highly energetic particles with velocities approaching the speed of light. Though these particles exist in many places throughout the universe – and can even be found slamming into our own atmosphere – scientists don’t yet fully understand their origins.
Nature’s High-Performance Accelerator
Celestial objects such as neutron stars or the remnants of exploded stars eject particles with energies exceeding the capability of the best accelerators on Earth by a factor of a thousand or more. Known as cosmic rays, these high-energy particles are capable of reaching Earth where they are studied either by satellite-based detectors, or from the ground with instruments that examine their interaction with the Earth’s atmosphere.
Though scientists have developed provisional models to explain the behavior of these particles, the mechanisms that underlie their acceleration are not fully understood. Scientists speculate, however, that explosions of massive stars, known as supernovae, and the resulting shock waves sent into the surrounding interstellar gas may provide the motive force. There is also emerging consensus that magnetic fields play a role in helping these particles achieve their enormous energies.
Understanding Natural Particle Acceleration Source
Scientists face significant challenges in seeking to identify and understand the sources of these highly energetic particles. The equations are highly complex and observations require precise instruments such as the Fermi Gamma-ray Space Telescope. Eventually, scientists may be able to use data from Fermi and other instruments to better understand these particles and build more powerful and efficient accelerators to replicate them on Earth.
Motivated by the rich data supplied by the Fermi Large Area Telescope, KIPAC researchers are vigorously pursuing an understanding of the phenomena responsible for acceleration of particles to enormous energies. To expand their view of the universe, KIPAC scientists are busy planning and conducting as radio, X-ray and optical observations of celestial sources of gamma-rays. KIPAC’s search runs the gamut from the exotic — remnants of exploded stars and astrophysical jets — to the seemingly mundane — our own Sun. Once thought to be an ordinary and quite stable star, the Sun is now known to contain very energetic particles. On occasion these particles penetrate the Earth's atmosphere, and can even briefly disrupt transmission of radio and TV signals.
Researchers at KIPAC are also engaged in studying the implications of these phenomena based on the analysis of data from various ground- and space-based observatories. Much of this work involves constructing detailed numerical simulations. These simulations suggest that shocks from stellar explosions compress the surrounding matter and ambient magnetic fields. Based on this research, KIPAC researchers have also concluded that magnetic fields are responsible for the collimated jets – straight and narrow flows of energy and matter – emanating from the centers of many galaxies.