This strange star system projects more gamma rays than expected

Our universe is filled with particles of high energy and light, which require enormous energy from the most extreme objects and processes imaginable. One of the biggest challenges facing astronomers is to determine how these cosmic and gamma rays are produced. Today, a unique event in life has made it possible to understand how pulsars accelerate the particles around them to produce a light of the highest energy, but observations show that our models of how this acceleration occurs may need a revision.

The work was published on October 31 in the Astrophysical Journal Letters. Astronomers have observed the closest approach to a pulsar (a fast-spinning neutron star emitting beams of radiation from its poles), PSR J2032 + 4127, to its massive binary companion of 39; Be star, MT91 213. The system, called gamma ray binary system because it produces a high energy light, is one of only two systems of this type in which a pulsar and a massive star revolve around their orbit. In addition, there are only about ten known binary systems with a massive star in orbit around a neutron star – not all neutron stars are considered as pulsars, which are only identified if the Neutron star is oriented in such a way that its poles swing the Earth turns.

Anticipate fireworks

The two stars of this system are in a 50-year orbit. The most recent approach between the stars took place on November 13, 2017. When the dust and gases of the massive companion approach too much of the pulsar, the particles are accelerated to near the speed of the light by the intense magnetic field of the pulsar. These particles then snap in all other nearby particles, generating a gamma ray flash, which astronomers can detect on Earth. As expected, the number of gamma rays seen by the system increased as the stars approached the closest point to their orbit. But unexpectedly, astronomers saw "a huge increase in the number of gamma rays" as the two stars approached their nearest point, said co-author Jamie Holder of the University of Delaware (UD ) in a press release. This peak, however, has occurred much faster than the predicted models, and "this tells us that we need to revise models of how this particle acceleration occurs," Holder said.

Thanks to the VERITAS system and the main MAGIC (Gamma Imaging Gamma Imaging Cherenkov) telescopes, the researchers started to monitor the system in September 2016. They monitored it throughout the year, anticipating the future. 39, the closest approach. In September 2017, observations showed not a slow and slightly variable increase in gamma rays, as predicted by the models, but a rapid increase in gamma rays in the system and wild day-to-day variability. "I got up every morning to check if we had new data, and then analyze it as quickly as possible, because there were times when the number of gamma rays we saw changed rapidly in a day or two," he said. co-author Tyler Williamson, currently PhD student at UD.