1967 In the fall, the great Princeton quantum physicist John Archibald Wheeler gave a lecture on pulsors at a conference where he said we should consider the possibility that the center of the pulsar is a completely collapsed object in terms of gravity. He noted that it was not always possible to say that “an object has completely collapsed by gravity.” That we needed a shorter descriptive phrase. “And what about the black hole?” Asked someone from the audience, giving birth to the name of one of the most paradoxical objects in the universe.
Fast forward to 2020 Two teams of astronomers searched for the missing compact object, which was supposed to consist of the remnants of a two-light-year-wide explosion of the Supernova 1987A, forcing them to wonder if it had collapsed into a Black Hole instead of a neutron star. A compelling 33-year mystery case was made based on Atacama Large Millimeter / submillimeter Array (ALMA) observations and theoretical follow-up. Scientists provide new insight into the argument that a neutron star hides in the remnants of a deeply exploding star, the youngest neutron star known to date.
There is a lack of evidence
Since 1987 February 23 Particles known as neutrinos were discovered on Earth, and astronomers expected a neutron star to form in the collapsed star center. But when scientists found no evidence of the star, they began to wonder if it could be Wheeler’s “completely collapsed object by gravity.” For decades, the scientific community has been eagerly awaiting a signal from this object hiding under a very thick cloud of dust.
Blob SN 1987A Center
Recent observations from the ALMA radio telescope revealed the first missing neutron star after the explosion. Extremely high-resolution images revealed a hot “spot” in the dusty core of the SN 1987A, which is brighter than its surroundings and corresponds to the suspected location of the neutron star.
“We were very surprised to see this thick cloud of dust made by a thick cloud of dust in the remnants of a supernova,” said Mikako Matsuura of Cardiff University and a member of the team that found the stain with ALMA. “There has to be something in the cloud that has warmed the dust and makes it shine. That’s why we suggested that a neutron star be hiding in a cloud of dust. “
The ultra-high-resolution ALMA images above revealed a hot “spot” in the dusty Supernova 1987A series (insert) that could contain the location of the missing neutron star. The red color indicates that there is dust and cold gas taken at radio wavelengths with ALMA at the center of the supernova remnant. Shades of green and blue show where the expanding shock wave from the exploding star meets the ring of matter around the supernova. Green indicates the brightness of visible light captured by NASA’s Hubble Space Telescope. The blue color reveals the hottest gas and is based on data from NASA’s Chandra X-ray Observatory. The ring was originally made so that it would illuminate from the flash of the initial explosion. In subsequent years, the material of the ring brightened considerably when a wave of explosion struck it.
While Matsuura and her team were excited about this result, they wondered about the brightness of the cloud. “We thought the neutron star might be too bright to exist, but then Dany Page [an astrophysicist at the National Autonomous University of Mexico] and his team has released a study stating that a neutron star can actually be as bright because it’s so young, ”Matsuura said.
“I was halfway through my doctorate when the supernova happened,” Pageas said, “it was one of the biggest events of my life that forced me to change my career path to try to solve this mystery. It was like a modern holy grail. “
“Despite the highest complexity of the supernova explosion and the extreme conditions in which the interior of the neutron star reigns, the detection of a warm dust bubble is a confirmation of several predictions,” said Pus and in his theoretical study. team, published today in the Astrophysical Journal, which strongly supports the ALMA team’s proposal that the neutron star be feeding the dust block.
Forecasts – location and temperature
These predictions were the location and temperature of the neutron star. According to supernova computer models, an explosion at a speed of hundreds of kilometers per second “threw” a neutron star from its homeland (ten times faster than the fastest rocket). The whip is exactly where astronomers think a neutron star would be today. And the temperature of the neutron star, which was predicted to be about 5 million degrees Celsius, provides enough energy to explain the brightness of the cloud.
“Probably not a pulsar”
“The power of a pulsar depends on how fast it rotates and on the strength of its magnetic field. Both of these parameters should be matched very precisely to match the observations, while the thermal energy emitted by the hot surface of the young neutron star is naturally consistent with the data, says a page suggesting that, contrary to expectations, the neutron star is 25 km wide, extremely hot a ball of matter – probably not a pulsar. A teaspoon of its material weighs more than all the buildings in New York. As it may only be 33 years old, she would be the youngest neutron star ever found. The second youngest neutron star we know of is in the supernova remnant Cassiopeia A and is 330 years old.
“The Neutron Star is behaving exactly as we expected,” added James Lattimer of Stony Brook University in New York and a member of the Page team. Lattimer also closely monitored SN 1987A before publishing predictions of the supernova neutrino signal, which later corresponded to the observations. Those neutrinos said the black hole never formed, and it seems difficult for the black hole to explain the observed brightness of the bubble. We compared all the possibilities and concluded that the quickest explanation is a hot neutron star. “
Waiting for the dust to settle
Only a direct image of a neutron star would provide clear evidence that it exists, but that may require astronomers to wait several more decades for the dust and gas in the supernova remnant to become more transparent.
Although many telescopes made images of the SN 1987A, none of them were able to observe its core with such high accuracy as the ALMA. Previous (3-D) observations with ALMA have already shown the types of molecules found in the supernova remnant and confirmed that it releases large amounts of dust.
“This discovery is based on many years of ALMA observations, increasingly detailing the supernova core as it continually improves telescope and data processing,” said Remy Indebetouw of the National Radio Astronomical Observatory and the University of Virginia. was part of the ALMA imaging team.
Sources: Spotting of ALMA: High Angle Images of ALMA Dust and Molecules SN 1987A Ejecta, by P. Cigan et al., Astrophysical Journal. https://doi.org/10.3847/1538-4357/ab4b46
Theoretical study in favor of the neutron star: NS 1987A SN 1987A, by D. Page et al., Astrophysical Journal. https://doi.org/10.3847/1538-4357/ab93c2
The Daily Galaxy, Max Goldberg, through the NRAO
Videos: Chandra X-ray Observatory at the top of the page and inserts ALMA (ESO / NAOJ / NRAO), P. Cigan and R. Indebetouw; NRAO / AUI / NSF, B. Saxton; NASA / ESA