Gamma-Ray Observations of Binary System Reveal Nature of Compact Component

(ORDO NEWS) — Gamma rays are the highest energy form of electromagnetic radiation, as each gamma ray photon has an energy hundreds of thousands of times greater than that of visible light photons.

Very high-energy gamma radiation exceeds optical radiation in energy by a factor of billions or even more. Astronomers believe that gamma rays are formed as part of the winds or jets from the compact, superdense remnants of massive stars that remain at the site of supernova explosions.

There are two types of compact remnants – black holes and neutron stars. Winds or jets from the vicinity of such objects can accelerate charged particles to speeds close to the speed of light, and the radiation scattered by such high-speed particles can acquire even greater energy,

Nine known or possible sources of gamma radiation are part of binary systems, where compact objects revolve around a star with periodic releases of energy. Each member of this group has its own unique characteristics, but in all but one case, the stellar component is known to be a massive, hot star, often surrounded by an equatorial disk.

At the same time, the nature of a compact object often remains undetermined. The gamma-ray emitting binary HESS J0632+057, located at a distance of about five thousand light-years from us in our Galaxy, corresponds to the hot optically observed star MWC 148 and its associated X-ray source. Scientists knew that this source emitted in the gamma range, as well as the periodicity of its X-ray emission,

In a new study, a team led by Wystan Benbow of the Harvard-Smithsonian Astrophysical Center, USA, set out to determine the nature of a compact object in the HESS J0632+057 system.

By analyzing a large number of X-ray and gamma-ray observations of this system, the team was able to determine for the first time a period of very high-energy gamma rays of 316.7 days with an uncertainty of 1.4 percent, which was consistent with period values ​​determined from observations at other wavelengths.

The close correlation between X-ray and gamma radiation from the source suggests that the same population of high-energy particles is responsible for both of these types of radiation, while the lack of correlation with the emission lines of atomic hydrogen implies, that any changes in the state of the hot star play only a minor role. For a deeper characterization of this source, the authors are planning further long-term multiwave observations of this source.

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