The James Webb Space Telescope has confirmed the distance of the farthest fast radio burst ever detected by observing its host galaxy. The signal, named FRB 20240304B, comes from the period of the universe just three billion years after the Big Bang. However, the researchers found a small galaxy that was forming new stars, about a thousand times less massive than they expected.
According to NASA’s October 8 statement, the MeerTRAP team detected the radio signal with the MeerKAT telescope on March 4, 2024 and determined its location in the sky. However, since ground telescopes could not see the galaxy at the same point, the team turned to Webb. Additionally, NIRCam images revealed the galaxy in the correct location.
The NIRSpec instrument measured the galaxy’s redshift as 2,148 and provided researchers with data to determine the distance. On the other hand, the young stars of the galaxy weaken the possibility of this explosion coming from the merger of two neutron stars, according to researchers. The team finds the possibility of a young magnetar carrying a strong magnetic field more suitable.
In addition, the radio signal carries the traces of the matter in the regions it passes through on its way to Earth to measurements and helps to investigate the space in between. The team distinguished the influence of the Virgo Cluster and another previously unknown galaxy cluster in the signal. However, there is no definitive evidence yet regarding the origin of the explosions.
NIRSpec measures distance by separating galaxy light
Webb’s technical description of NIRSpec explains that the device creates a spectrum by separating incoming light into different wavelengths and explains the basis of the measurement. In addition, atoms and molecules leave their own unique lines in this spectrum. Thus, researchers can examine the chemical and physical properties of the galaxy instead of just looking at its image.
However, NIRSpec captures wavelengths ranging from visible red light to infrared and is aimed at very faint distant targets. Long observation times are required to collect enough light from some targets, so efficiency is important. The device offers the opportunity to collect spectra of approximately a hundred objects simultaneously.
To provide this capacity, NASA Goddard engineers developed a mechanism consisting of very small valves that control incoming light. Additionally, managing each shutter separately helps block light from close, bright targets while observing the desired part of the sky. This makes it easier to separate the light of faint galaxies from other sources.
On the other hand, the integrated field mode of the device allows to extract the spectra of different points in the same field of view separately. With this method, astronomers can study how temperature, composition, and motion vary from one region to another. Therefore, in the new radio burst study, imaging and spectral measurement complement each other to determine the position and distance of the same target.