Capturing Gamma Rays with Precision: Kobe University’s Breakthrough Discovery

By superimposing several thin films, we have precisely captured the gamma rays emitted by a neutron star. Provided by Kobe University in Japan

By stacking photographic film like a “pancake,” gamma rays emitted by the neutron star were captured with an accuracy of 1/10 of a millionth of a milliliter (ml).

A research team led by Shigeki Aoki, professor of astrophysics at Kobe University in Japan, managed to precisely capture the neutron star “Vela pulsar” by stacking and arranging films on a “balloon telescope” for observation of gamma rays, on the 21st (local time). ) was published in the international academic journal “Astrophysical Journal”.

Gamma rays are high-energy electromagnetic waves generated by bursts of gamma rays in space. This is known to happen when two neutron stars approach each other and collide. Neutron stars that collide in this way sometimes collapse into black holes, and attempts are being made to discover 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 it 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 floated a balloon-borne telescope into the stratosphere and accurately observed gamma rays with energies equivalent to 10 megavolts (MeV) and 100 gigavolts (GeV). Unlike the James Webb Space Telescope, which is launched into space, the balloon telescope is an observing device that is launched into Earth’s stratosphere. When a gamma-ray telescope is lifted onto a large helium balloon, the telescope floats into the sky and detects space particles.

The research team focused on “photographic film” as a means of increasing the acquisition capacity of the balloon telescope. It was believed that by increasing the sensitivity of the photographic film installed in the telescope, gamma rays emitted by neutron stars could be captured with greater precision. 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 on several sheets of film, the trajectory of the particles’ movement can be observed more precisely.

Furthermore, 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 deduced by leaving a trace of the passage of time on the film lying on the floor, just as the pendulum of a clock moves.

After observing the neutron star Mast Pulsar, through a telescope made with this method, the research team was able to capture the gamma rays emitted by the Mast Pulsar with a precision of 1/10,000 of a millimeter. The research team explained that the result was approximately 40 times more accurate than previously acquired 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.”