By stacking several thin films, we accurately captured the gamma rays emitted by a neutron star. Provided by Kobe University in Japan
By stacking photographic film like a ‘pancake’, the gamma rays emitted by the neutron star were captured with an accuracy of 1/10 millionth of a milliliter (ml).
A research team led by Shigeki Aoki, a professor of astrophysics at Kobe University in Japan, succeeded in accurately capturing the neutron star ‘Vela pulsar’ by stacking and arranging films on a ‘balloon telescope’ for gamma-ray observation, on the 21st (local time). ) was published in the international academic journal ‘Astrophysical Journal’.
Gamma rays are high-energy electromagnetic waves generated by gamma-ray explosions in space. It is known to occur when two neutron stars get close to each other and collide. Neutron stars that collide in this way sometimes collapse into black holes, and attempts are being made to find the principles of black holes through gamma-ray analysis.
However, gamma rays have the highest energy in the electromagnetic spectrum and have a very short wavelength. Because the wavelength is so short that it is difficult to observe directly, the astrophysics community is developing more precise measurement methods, such as developing special equipment to measure gamma rays.
In December 2021, the research team announced that they had floated a balloon-borne telescope in the stratosphere and accurately observed gamma rays with energies equivalent to 10 megavolts (MeV) to 100 gigavolts (GeV). Unlike the James Webb Space Telescope, which is launched in space, the balloon telescope is an observation device that is launched in the Earth’s stratosphere. When a gamma-ray telescope is lifted up on a large helium balloon, the telescope floats in the sky and detects space particles.
The research team focused on ‘photographic film’ as a means to increase the capturing ability of the balloon telescope. It was believed that by increasing the sensitivity of the photographic film installed in the telescope, gamma rays emitted from neutron stars could be captured more accurately. The research team devised a method of stacking several thin films on top of each other like pancakes. The assumption is that if the particles captured by the lens are stacked over several sheets of film, the trajectory of the particles’ movement will be able to be observed more precisely.
In addition, in order to analyze when the gamma rays recorded on the film were generated, the three layers of the bottom film were designed to move back and forth at different speeds. The time at which the gamma ray was captured was inferred by leaving a trace of the passage of time on the film laid on the floor, just as a clock pendulum moves.
As a result of the research team’s observation of the neutron star, the Mast Pulsar, through a telescope made using this method, they were able to capture the gamma rays emitted by the Mast Pulsar with an accuracy of 1/10,000th of a millimeter. The research team explained that the result was about 40 times more accurate than previously captured results.
The research team said, “We will expand the observation area and observation time period in future experiments using balloon telescopes to produce innovative results in the field of gamma-ray astronomy.”
A balloon telescope takes off toward the stratosphere from Alice Springs, Australia. Provided by Kobe University
