admin The data confirm that these bright objects do indeed exceed the Eddington limit and suggest that their intense luminosity can be attributed to the strong magnetic fields of the ULXs.
Breaking the Limit: Unraveling the Brightness Puzzle
Astonishingly bright cosmic objects called ultra-luminous X-ray sources (ULXs) have long baffled scientists, as they seemingly exceed the Eddington limit-a physical constraint on an object’s brightness based on its mass-by 100 to 500 times. Observations from NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) have now provided evidence supporting a possible solution to this conundrum.
Unprecedented Measurements Confirm Limit-Breaking Brightness
In a reserch paper published in The Astrophysical Journal, researchers reveal the first-ever measurement of a ULX using NuSTAR. The data confirms that these luminous objects indeed surpass the Eddington limit, and suggests that their intense brightness could be attributed to the ULXs’ powerful magnetic fields. However, as these magnetic fields are billions of times stronger than the most potent magnets on Earth, scientists can only test this hypothesis through observations.
The Significance of Exceeding the Eddington Limit
When an object reaches the Eddington limit, the outward push of light particles, or photons, overcomes the object’s gravitational pull. This is crucial since material falling onto a ULX is the source of its brightness. Initially, scientists believed that ULXs were black holes surrounded by luminous clouds of gas. However, in 2014, NuSTAR data revealed that M82 X-2, a ULX, is actually a less-massive object called a neutron star.
Neutron Stars: The Key to ULX Brightness
Neutron stars form when a star dies and collapses, packing more mass than our Sun into an area roughly the size of a mid-size city. Their extreme density generates a gravitational pull at the surface about 100 trillion times stronger than Earth’s. This force drags in gas and other materials, accelerating them to millions of miles per hour and releasing enormous energy when they collide with the neutron star’s surface. This process produces the high-energy X-ray light detected by NuSTAR.
Shedding Light on M82 X-2’s Brightness
The recent study focused on M82 X-2 and discovered that it is siphoning approximately 9 billion trillion tons of material per year from a nearby star-around 1.5 times the mass of Earth. By determining the amount of material striking the neutron star’s surface, scientists could estimate the ULX’s brightness. Their calculations aligned with independent measurements, confirming that M82 X-2 surpasses the Eddington limit.
Magnetic Fields: The Key to ULXs’ Maximum Brightness
If researchers can validate the brightness of more ULXs, they might disprove a hypothesis suggesting that the apparent brightness of these objects is due to an optical illusion created by strong winds forming a hollow cone around the light source. Instead, an alternative hypothesis backed by the recent study posits that powerful magnetic fields could distort atoms into elongated shapes, reducing photons’ ability to push atoms away and thus increasing an object’s maximum possible brightness.
According to Matteo Bachetti, lead author of the study and astrophysicist at the National Institute of Astrophysics’ Cagliari Observatory in Italy, these observations enable scientists to explore the effects of incredibly strong magnetic fields that are impossible to recreate on Earth. Through these studies, researchers are gradually uncovering the secrets of the universe.
