Student-built satellite detects likely merger of neutron stars 3 billion light years away

EIRSAT-1, the student-built satellite from University College Dublin (UCD) that was launched into space last December, detected two separate gamma-ray bursts on 21 August. One of the gamma-ray bursts has been confirmed by the European Southern Observatory (ESO) ground and space telescope network to emanate from 3 billion light years away—likely a merger of two neutron stars.

The miniature cube satellite, or cubesat, was designed, built, and tested at UCD under guidance of the European Space Agency (ESA) Education division “Fly Your Satellite” program, and is Ireland’s first-ever satellite.

One of the payloads on board the satellite is the gamma-ray detector—the Gamma-ray Module (GMOD). It has been the first experiment in-orbit to net a major success for the mission. The module was designed to detect bursts of high energy radiation emitted from the biggest, most destructive events in the universe such as the formation of a black hole from a collapsar (dying massive star) or the merging of neutron stars.

The Irish cubesat detected both its first and its second gamma-ray bursts within about 80 minutes of each other. Different spacecraft also reported these gamma-ray bursts, confirming the detections and validating the full GMOD instrument performance in-orbit—a great moment for the UCD team and the ESA program, which hails EIRSAT-1 as a flagship project.

Post-doctoral researcher in UCD Space Science Group and EIRSAT-1 Systems Engineer and GMOD Lead, Dr. David Murphy said, “It was incredibly exciting to downlink the data from GMOD and discover such clear unambiguous detections of these two gamma-ray bursts. Having spent so many years designing, building and testing the GMOD instrument as well as calibrating it and figuring out how to operate it in-orbit, these detections are an amazing validation of all the hard work put in by the team.

“It’s astonishing to think that this satellite that we hand-built in our lab is now in space detecting photons that have traveled across the universe for billions of years to reach it. It’s a real boost for us as we’re beginning work on bigger and better space missions.”

ESA congratulated the team on the “groundbreaking gamma-ray burst detections” on X, posting: “EIRSAT-1 is making waves in the scientific community, congratulations to the team and everyone involved!”

Gamma-ray bursts only last seconds or minutes but they are incredibly intense and can cross vast intergalactic distances to be picked up by GMOD. As EIRSAT-1 orbits earth from pole to pole, GMOD’s design and calibration enables fully optimized instrument performance when operational, as well as the ability to switch off to avoid overloading the on-board computer in high radiation regions around the poles, giving it the best chance of detecting the elusive gamma-ray bursts.

EIRSAT-1 Science Lead and gamma-ray expert, Professor Sheila McBreen said, “The detection of these bursts is a major milestone for the EIRSAT-1 mission and the GMOD instrument. GMOD was designed, built and integrated in UCD, all the code to run it was developed in UCD, and it is now working in-orbit and has detected events caused by end points of stars. We hope these events are the first of many detected by GMOD on EIRSAT-1 and future instruments we are already developing in the Space Science Group.”

Optical light produced in the aftermath and environment of a gamma-ray burst can be used to measure its distance. To further examine the detected events, gamma-ray burst and pulsar expert at UCD, Dr. Antonio Martin Carrillo and his collaborators used an eight-meter telescope at the European Southern Observatory (ESO) in Chile. They found that one of the gamma-ray bursts detected by GMOD is roughly 3 billion light years away and likely the result of two neutron stars merging.

He said, “After the detection of a new gamma-ray burst, as part of an international collaboration with a large ESO program, my international colleagues and I searched for its optical counterpart to find its distance. This is a fundamental step to understanding the true energy power of these events.

“With the aid of other space and ground-based telescopes, we were able to pinpoint the sky coordinates of one of EIRSAT-1’s gamma-ray bursts. I coordinated a series of observations with the eight-meter VLT telescopes at Cerro Paranal (Chile) to gather the necessary data to constrain its distance. Its relative proximity and the properties of the optical counterpart seem to suggest that it was produced by the merger of two compact objects, likely neutron stars.”