Wednesday 19 March 2025
Scientists have made a fascinating discovery about a type of star that’s often overlooked in our galaxy. GX 9+1, a neutron star low-mass X-ray binary, has been found to exhibit polarized light emission, which is a rare phenomenon.
Neutron stars are incredibly dense objects, formed when massive stars collapse under their own gravity. They’re so dense that a sugar-cube-sized amount of their material would have a mass equivalent to that of a mountain. GX 9+1, in particular, is a type of neutron star known as an atoll source, which means it’s relatively calm and doesn’t exhibit the intense activity seen in other types of X-ray binaries.
The discovery was made possible by the Imaging X-ray Polarimetry Explorer (IXPE), a spacecraft designed to study the polarization properties of X-rays emitted by celestial objects. Polarization occurs when light waves vibrate in a specific direction, kind of like how ripples on a pond can be aligned parallel or perpendicular to each other.
The researchers found that GX 9+1 emits polarized light in the softer energy ranges (2-3 keV and 2-4 keV), but not in the higher energy ranges (4-8 keV). This suggests that there are different mechanisms at play, depending on the energy of the X-rays. The soft X-rays are likely produced by thermal emission from the neutron star’s surface, while the harder X-rays might be generated through Compton scattering, a process where high-energy particles interact with electrons.
The team also observed that the polarization degree (PD) is higher in the softer energy ranges, which could indicate that the radiation is being scattered or absorbed by material close to the neutron star. This suggests that there’s a complex geometry at play, possibly involving a corona of hot gas surrounding the neutron star and an accretion disk feeding it.
The discovery has significant implications for our understanding of these enigmatic objects. GX 9+1 provides a unique window into the internal workings of neutron stars, which are still poorly understood despite being one of the most extreme environments in the universe. By studying the polarization properties of X-rays emitted by neutron stars like GX 9+1, scientists can gain insights into their internal structure and behavior.
The IXPE mission has already opened up new avenues for research, and future observations will likely shed more light on the mysteries surrounding these cosmic objects.
Cite this article: “Polarized Light Emission from Neutron Star GX 9+1 Reveals Hidden Geometry”, The Science Archive, 2025.
Neutron Stars, Ixpe, Polarization, X-Rays, Gx 9+1, Atoll Source, Celestial Objects, Imaging X-Ray Polarimetry Explorer, Thermal Emission, Compton Scattering
