Evidence for Proton Acceleration to TeV Energies in Cassiopeia A
This presentation explores groundbreaking observations of the Cassiopeia A supernova remnant using VERITAS and Fermi-LAT telescopes, revealing evidence that protons are accelerated to multi-TeV energies through gamma-ray spectral analysis. The talk examines how the detection of spectral curvature consistent with pion decay, combined with a spectral cutoff at 2.3 TeV, demonstrates hadronic contributions to cosmic ray acceleration while also revealing fundamental limits on Cas A's role as a cosmic ray source for our galaxy.Script
A 350-year-old stellar explosion called Cassiopeia A may hold the key to one of astrophysics' most persistent mysteries: where do cosmic rays get their extraordinary energies? New observations reveal something unexpected about the limits of particle acceleration in supernova remnants.
Supernova remnants like Cas A are thought to maintain the cosmic ray energy flux throughout our galaxy. But proving that protons reach truly extreme energies requires catching the gamma rays produced when those protons collide with surrounding matter.
Two complementary telescopes joined forces to observe Cas A across an unprecedented energy range.
Fermi-LAT detected a telltale spectral curve at lower energies, the signature of neutral pions decaying after proton collisions. VERITAS extended measurements into the TeV regime, revealing where the acceleration process reaches its limits.
When the researchers combined data from both telescopes, the spectrum revealed a cutoff at 2.3 TeV. This proves protons reach at least 6 TeV but also shows Cas A cannot accelerate particles to the PeV energies needed to fully explain galactic cosmic rays.
The cutoff tells us something profound about the physics of particle acceleration. Cas A falls short of being a true cosmic ray powerhouse, yet the observations reveal magnetic field amplification at work, a key ingredient in the acceleration process that future instruments might map in unprecedented detail.
A centuries-old stellar explosion continues teaching us why the universe cannot quite turn every supernova remnant into a cosmic particle accelerator. Visit EmergentMind.com to explore more research and create your own lightning talk videos.
