2023-12-24 19:00:00
In an astonishing fusion of ancient and modern techniques, researchers from theKobe University managed to capture the most precise image ever made of a gamma-ray beam from a neutron star, using a balloon carrying a stack of films sensitive to radioactivity. This discovery could open up new perspectives in the study of stellar phenomena.
An innovative method for capturing gamma rays
Stars flood us with their light across the entire light spectrum, from infrared to gamma rays. For each band in this spectrum, different detection equipment is required. Gamma rays, the high-energy products of nuclear fission, are particularly difficult to detect because of their very short wavelength which does not allow them to interact with matter in the same way as other forms of light.
Faced with this challenge, Kobe University astrophysicist, AOKI Shigekiand his team used the very first material used to detect radioactivity: photographic film.
« Our group emphasized the excellent ability of emulsion film to trace gamma rays with high precision and proposed that it could become an excellent gamma ray telescope by introducing several modern features for capturing and analyzing gamma rays. data », explains the astrophysicist.
Credit: SEED collaboration
Films, a balloon and a time recording device
The researchers stacked several photographic films to precisely capture the trajectory of particles produced by the impact of gamma rays. To reduce atmospheric interference, they mounted this stack of films on a scientific observation balloon, hoisting it to a height between 35 and 40 kilometers.
However, the balloon being subject to wind movements, the orientation of the “telescope» is not stable. So the researchers added a set of cameras to record the pod’s orientation relative to the stars at all times. To overcome the problem of recording time, they made the bottom three layers of film move at regular but different speeds, like the hands of a clock.
Credit: SEED collaboration
A new image of the Vela pulsar
The researchers published the first image obtained using this device in The Astrophysical Journal. It is the most precise image ever produced of the Vela pulsar, a rapidly rotating neutron star that projects a beam of gamma rays into the sky like a beacon in the night.
« We captured a total of several trillion traces with a precision of 1/10,000 millimeters. By adding temporal information and combining it with attitude monitoring information, we were able to determine ‘when’ and ‘where’ events took place with such precision that the resolution achieved was more than 40 times greater than that of conventional gamma-ray telescopes », résume Aoki Shigeki.
Credit: SEED collaboration
Synthetic
This new technique offers the ability to capture more detail in this frequency band of light than ever before.
« Through experiments carried out with scientific balloons, we can attempt to contribute to many areas of astrophysics, and in particular to open up gamma-ray telescopy to ‘multi-messenger’ astronomy where simultaneous measurements of the same event captured by different techniques are required », Explains the researcher from Kobe University.
For a better understanding
What is a gamma ray?
A gamma ray is a form of very high energy light or electromagnetic radiation. They are produced by nuclear and subatomic processes such as nuclear fission.
What is a neutron star?
A neutron star is the compact remnant of a massive star that exploded as a supernova. It is mainly composed of neutrons, hence its name.
What is the Vela pulsar?
The Vela pulsar is a neutron star that was first discovered in 1968. It is known for its rapid rotation and intense gamma ray beam.
Gamma rays are usually detected using specific detectors that can measure their very high energy. In this study, the researchers used an innovative method involving photographic films sensitive to radioactivity.
What are the implications of this discovery?
This discovery could open up new perspectives in the study of stellar phenomena, particularly in the field of gamma-ray astronomy.
References
Article : “First emulsion γ-ray telescope imaging of the Vela pulsar by the GRAINE 2018 balloon-borne experiment” – DOI: 10.3847/1538-4357/ad0973
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