One new theory could put some long-standing physics mysteries to rest. A recent astrophysical model suggests that three different types of high-energy “cosmic messenger particles” could all originate from the same phenomenon.
The theory
asserts that these particles — ultrahigh-energy cosmic rays, very high-energy
neutrinos, and high-energy gamma rays — were potentially all shot into space
after jets from supermassive black holes accelerated cosmic rays.
Developed by
scientists from Penn State and the University of Maryland, this model is the
first astrophysical model of its kind. A paper describing it and its
computational basis was recently published in the journal Nature Physics.
Kohta
Murase, an assistant professor of physics and astronomy and astrophysics at
Penn State, stated in a press release: “Our model shows a way to understand why
these three types of cosmic messenger particles have a surprisingly similar
amount of power input into the universe, despite the fact that they are
observed by space-based and ground-based detectors over ten orders of magnitude
in individual particle energy.”
An artist’s
interpretation of a “multi messenger” emission from cosmic rays, accelerated by
jets from a supermassive black hole. Image Credit: Kanoko Horio
Murase went
on to explained that neutrinos and gamma rays, as suggested by the model, are
produced naturally by particle collisions as offspring particles of cosmic
rays. This means that they “inherit” the energy of their parent particles,
explaining why the three cosmic messengers have similar energies.
COSMIC
MESSENGER PARTICLES
Each of
these three extreme-energy particles has a host of unique qualities, but all
share ultra-high energy levels. Neutrinos are inherently elusive and highly difficult to find, though high-energy neutrinos can and have been detected in
the IceCube neutrino observatory in Antarctica. High-energy gamma rays have the
highest-known electromagnetic energy. Ultra high-energy cosmic rays are mostly
atomic nuclei, but sometimes other particles, that travel at a speed close to
the speed of light.
The method
used by this research team found that this “multi-messenger approach” of the
three cosmic messenger particles can be explained by numerical simulations.
“Our work
demonstrates that the ultrahigh-energy cosmic rays escaping from active
galactic nuclei and their environments, such as galaxy clusters and groups, can
explain the ultrahigh-energy cosmic-ray spectrum and composition,” said Ke
Fang, a postdoctoral associate at the University of Maryland, in the press
release. “Simultaneously, the very high-energy neutrino spectrum above one
hundred million mega-electronvolts can be explained by particle collisions
between cosmic rays and the gas in galaxy clusters and groups.”
The revelation
provided through this model’s simulations serves to resolve previous discrepancies in physics and our understanding of the universe. It is a step
towards creating a unifying model of how these three extreme-energy particles
are physically connected. This method also pushes forward multi-messenger astronomy, which uses both theory and data from all three particles.
“The golden
era of multi-messenger particle astrophysics started very recently,” explained
Murase in the press release. “Now, all information we can learn from all
different types of cosmic messengers is important for revealing new knowledge
about the physics of extreme-energy cosmic particles, and a deeper
understanding about our universe.”
References:
Space.com, Nature, Penn State University
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