Astronomers have unveiled a remarkable discovery in the heart of the Milky Way: 4XMM J174610.7–290020, a very faint X-ray transient (VFXT) located approximately 26,700 light years from Earth. This new celestial object, known as Swift J174610–290018, was detected by NASA’s Swift spacecraft in mid-February 2024. This new VFXT is found nearly 6.7 arcminutes east of Sagittarius A*, the supermassive black hole at the center of our galaxy. It enriches the growing list of transient phenomena.
The discovery of 4XMM J174610.7–290020 is an important one. Despite being present in many distant galaxies, only a handful of VFXTs have been detected in the Milky Way, with about a dozen located at the galactic center. The object showed two spectacular outbursts in 2024 and 2025, which is allowing astronomers an unprecedented look at the object’s nature and behavior.
Notable Outbursts Captured
In 2024, 4XMM J174610.7–290020 had its first recorded outburst. It lasted an amazing 50 days and peaked at a luminosity of 10-120 decillion erg/s! The second outburst, which took place in 2025, was much shorter—only five days. Over the course of this time, it produced beautiful luminosities between 60 and 90 decillion erg/s.
The spectral analysis of these outbursts indicated the presence of a strong, complex iron feature, possibly pointing to unique characteristics inherent to this VFXT. Scientists led by Giovanni Stel are specially focused on figuring out the cause of these outbursts.
“We aim to characterize the outburst that occurred in 2024, and a second, distinct outburst in 2025 to understand the nature and accretion flow properties of this new VFXT,” – Giovanni Stel
We identify mechanisms responsible for these outbursts to inform the nature of the outbursts and their contribution toward the VFXT population, paving the way for future analysis.
Insights into Neutron Star-Low Mass X-ray Binary Connection
Detailed study of 4XMM J174610.7–290020 shows it to be a likely NS-LMXB. The outbursts show some interesting features. Our best explanation is that a massive accretion disk forming a thick donut around the object is shielding its radiation.
“This scenario explains the overall low luminosity of this transient and the peculiar iron lines in the spectrum,” – the authors of the paper
These new results contribute greatly to our understanding of such unique objects as neutron stars. They do so by slowly revealing how these stars influence their surroundings and manifest as X-ray transients.
Implications for Galactic Research
The discovery of 4XMM J174610.7–290020 raises fundamental questions about the nature of VFXTs in our own galaxy. This finding increases the currently tiny sample of known objects of this type. It points to the very real need for continued observation.
The research team hopes to investigate more deeply into the details around the object’s behavior and properties in future studies. These findings have implications beyond this particular transient. They improve our understanding of the evolution of stars, and they show us the nature of exploding binary infringing in galactic center.