Evidence of a long-sought hypothetical particle could have been hiding in ordinary (X-ray) sight all along.
The X-ray emission from a collection of neutron stars, known as the Magnificent Seven, is so excessive that it can come from actions, a long-predicted type of particle, forged in the dense core of these dead objects, scientists have said. showed.
If their findings are confirmed, this discovery could help unravel some of the mysteries of the physical universe – including the nature of the mysterious dark matter that holds it all together.
“Finding actions has been one of the greatest efforts in high-energy particle physics, both in theory and in experiments,” said astronomer Raymond Co of the University of Minnesota.
“We think actions can exist, but we have not yet discovered them. You can consider actions as ghost particles. They can be anywhere in the universe, but they do not have a strong interaction with us, so we have no observations. of them not yet. ‘
Actions are low-mass hypothetical particles, first theorized in the 1970s to solve the question of why strong atomic forces follow something called charge parity symmetry, when most models say it is not necessary.
Actions are predicted by many models of string theory – a proposed solution to the tension between general relativity and quantum mechanics – and actions of a specific mass are also a strong candidate for dark matter. Scientists therefore have a number of very good reasons to go looking for them.
If it exists, actions are expected to be produced inside stars. These star actions are not the same as dark matter actions, but their existence implies the existence of other types of actions.
One way to look for actions is by looking for excess radiation. Actions in pairs of photons are expected to decay in the presence of a magnetic field – so if there is more electromagnetic radiation than there would be in an area where this decay is expected to occur, it could be evidence of actions.
In this case, excess hard X-rays are exactly what astronomers have found when looking at the Magnificent Seven.
These neutron stars – the collapsed nucleus of dead massive stars that died in a supernova – were not grouped together, but have a number of features in common. They are all isolated neutron stars of about middle age, several hundred thousand years since star death.
They all cool down, emitting low-energy (soft) X-rays. They all have strong magnetic fields, trillions of times stronger than Earth, powerful enough to cause action decay. And they are all relatively close, within 1500 light-years from Earth.
It’s an excellent laboratory for action, and when a team of researchers – led by senior author and physicist Benjamin Safdi of the Lawrence Berkeley National Laboratory – studied the Magnificent Seven with multiple telescopes, they were high-energy. (hard) X identified. radiation emission is not expected for neutron stars of this type.
In space, however, there are many processes that can cause radiation, so the team had to carefully investigate other potential sources of the emission. Pulsars, for example, emit hard X-rays; but the other forms of radiation emitted by pulses, such as radio waves, are not in the Magnificent Seven.
Another possibility is that unresolved sources near the neutron stars could cause the hard X-ray emission. But the data sets the team used, from two different space beam observations – XMM-Newton and Chandra – indicated that the emission from the neutron stars was coming. The team also found that the signal was probably not the result of an accumulation of soft X-rays.
“We are fairly confident that this co-payment exists, and very confident that there is something new among this excess,” Safdi said. “If we were 100 percent sure that what we saw was a new particle, it would be big. It would be revolutionary in physics.”
This is not to say that the excess is a new particle. This may be a previously unknown astrophysical process. Or it could be something as simple as an artifact of the telescopes or data processing.
“We do not yet claim that we discovered the action, but we do say that the extra x-rays can be explained by actions,” Co said. “It’s an exciting discovery of the excess in the X – rays, and it’s an exciting possibility that is already in line with our interpretation of actions.”
The next step will be to try to verify the finding. If the excess is produced by actions, most radiation must be emitted at higher energies than XMM-Newton and Chandra can detect. The team hopes to use a newer telescope, NASA’s NuSTAR, to observe the Magnificent Seven over a wider range of wavelengths.
Magnetized white dwarf stars could be another place to look for action emissions. Like the Magnificent Seven, these objects have strong magnetic fields and are not expected to produce hard X-ray emission.
“It starts out pretty convincing that it’s something out of the standard model if we see an X-ray excess there as well,” Safdi said.
The research was published in Physical overview letters.