Star Formation Regions

Particle Acceleration by Young Stars

Although the usual assumption is that supernova explosions are the dominant source of cosmic rays, it has been speculated that cosmic rays are also accelerated in stellar winds around massive young stars before they explode as supernovae, or around star clusters. Indeed, there is growing evidence from gamma-ray data for a population of sources related to young stellar clusters and environments with strong stellar winds. However, lack of detection sensitivity currently prevents the detailed study and clear identification of these sources of gamma radiation.

CTA aims at a better understanding of the relationship between star formation processes and gamma-ray emission. CTA can establish experimentally whether there is a direct correlation between star formation rate and gamma-ray luminosity when convection and absorption processes in the different environments are taken into account.

 

Dymanic duo - the two starburst galaxies NGC 253 (left) and M82 (right) produce VHE gamma rays. Image credits: NGC 253- ESO; M82 - NASA/STScI

 

Starburst Galaxies

Starburst galaxies are undergoing rates of star formation much higher than in our own galaxy. Both the VERITAS and H.E.S.S. arrays have performed deep observations of the nearest starburst galaxies, and found them, at the limit of their sensitivity, emitting TeV gamma-rays. Future CTA observations, with improved sensitivity at higher and lower energies, will reveal details of this radiation which in turn will help to understand the spectra, provide constraints on the physical emission scenarios, and extend the study of the relationship between star formation processes and gamma-ray emission to extragalactic environments.

 

Further Reading

Ohm et al., H.E.S.S. Observations of Massive Stellar Clusters; http://arxiv.org/abs/0906.2637

Romero et al., Gamma Rays from Massive Protostars; http://arxiv.org/abs/0908.0931