In the fall of 1967, the great quantum physicist at Princeton, John Archibald Wheeler, gave a lecture on pulsars in a lecture in which he argued that we should consider the possibility that the center of a pulsar was a totally gravitational object. He remarked that one could not continue to say “gravitationally collapsed object” over and over again. That we needed a shorter descriptive sentence. What about the black hole? asked someone in the audience, giving birth to the name of one of the most paradoxical objects in the universe.
As early as 2020, two teams of astronomers searched for a missing compact object that should have formed in the remnants of the 1987A Supernova light two-year explosion, leading them to wonder if instead of a neutron star would have collapsed into a black hole. A compelling case has been made in the 33-year mystery based on observations from the Atacama Large Millimeter / Submillimeter Array (ALMA) and a theoretical follow-up study. Scientists provide a new insight into the argument that a neutron star hides in the remnants of the exploded star, the youngest neutron star known to date.
Evidence is missing
Because particles known as neutrinos were detected on Earth on February 23, 1987, astronomers expected a neutron star to have formed at the collapsed center of the star. But when scientists found no evidence for this star, they began to wonder if it could be Wheeler’s “gravitationally completely collapsed object.” For decades, the scientific community has been eagerly awaiting a sign of this object hiding behind a very thick cloud of dust.
The “Blob” in Core of SN 1987A
Recently, observations from the ALMA radio telescope provided the first indication of the missing neutron star after the explosion. Extremely high-resolution images revealed a hot “bomb” in the dusty core of SN 1987A, brighter than its surroundings and coinciding with the presumed location of the neutron star.
“We were very surprised to see that this warm light bulb made by a thick cloud of dust on the remnant of the supernova,” said Mikako Matsuura of Cardiff University and a team member who found the group with ALMA. “There must be something in the cloud that has warmed the dust and made it glow. That’s why we suggested there be a neutron star hiding inside the dust cloud.”
The high-resolution ALMA images shown at the top revealed the hot “good” of the dusty nucleus of Supernova 1987A (inserted), which could be the location of the missing neutron star. The red color shows dust and cold gas in the center of the supernova remnant, taken at the wavelengths of the radio with ALMA. The green and blue hues reveal where the expanding shock wave of the exploded star collides with a ring of material around the supernova. Green represents the glow of visible light, captured by NASA’s Hubble Space Telescope. The color blue reveals the hottest gas and is based on data from NASA’s Chandra X-ray Observatory. The ring was initially glowed by the beam of light from the original explosion. Over the years, the ring material has shone considerably as the shock wave of the explosion climbs toward it.
Although Matsuura and his team were excited about this result, they wondered about the brilliance of the temperament. “We thought the neutron star might be too bright to exist, but Dany Page [an astrophysicist at the National Autonomous University of Mexico] and his team published a study that indicated that the neutron star can actually be so bright because it’s very young, ”Matsuura said.
“I was halfway through my doctorate when the supernova passed,” Page said, “it was one of the big events of my life that made me change the course of my career to try to solve this mystery. a modern holy grail. ”
“Despite the supreme complexity of a supernova explosion and the extreme conditions prevailing inside a neutron star, the detection of a hot spot of dust is a confirmation of several predictions,” Page explained in ‘theoretical study of Page and his. a team, published today in The Astrophysical Journal, that strongly supports the ALMA team’s suggestion that a neutron star is feeding dust.
Predictions: location and temperature
These predictions were the location and temperature of the neutron star. According to supernova computer models, the explosion has “pulled” the neutron star from its birthplace at a speed of hundreds of kilometers per second (tens of times faster than the fastest rocket). The bubble is exactly where astronomers believe it would be the neutron star today. And the temperature of the neutron star, which was projected to be about 5 million degrees Celsius, provides enough energy to explain the brightness of the lid.
“Probably not a boost”
“The power of a pulsar depends on the rotating speed and its magnetic field strength, both should have very fine-tuned values to match the observations, while the thermal energy emitted by the hot surface of the star of young neutrons naturally adapts to The data, said Page, which suggest that, contrary to common expectations, the neutron star – a 25 km wide ball and an extremely hot ball of ultra-dense matter – “Probably not a bracelet. A teaspoon of its material would weigh more than all the buildings in New York City combined. Since it can only be 33 years old, it would be the youngest neutron star ever found.” The youngest neutron star we know is in the rest of the supernova Cassiopeia A and is 330 years old.
“The neutron star is behaving exactly as expected,” added James Lattimer, of Stony Brook University in New York and a member of Page’s research team. Lattimer has also closely followed SN 1987A, having published SN 1987A predictions about the neutrino signal of a supernova that later coincided with the observations. “These neutrinos suggested that a black hole never formed, and moreover, it seems difficult for a black hole to explain the observed brightness of the ink. We compared all the possibilities and came to the conclusion that a hot neutron star is the most likely explanation. “
Waiting for the dust to settle
Only a direct image of the neutron star will certainly prove that it exists, but it is possible that astronomers will have to wait a few more decades until the dust and gas in the supernova’s remnant become more transparent.
Although many telescopes have taken images of SN 1987A, none of them have been able to observe its core as accurately as ALMA. Previous observations (3-D) with ALMA already showed the types of molecules found in the supernova remnant and confirmed that they produced massive amounts of dust.
“This discovery is based on years of ALMA observations, showing more and more detail about the supernova’s core thanks to continuous telescope improvements and data processing,” said Remy Indebetouw of the National Radio Astronomy Observatory and of the University of Virginia, which has been part of the ALMA imaging team.
Sources: ALMA observation of the “blob”: “High Angular Resolution ALMA Images of Dust and Molecules in the SN 1987A Ejecta”, by P. Cigan et al., The Astrophysical Journal. https://doi.org/10.3847/1538-4357/ab4b46
Theoretical study favoring a neutron star: “NS 1987A in SN 1987A,” by D. Page et al., The Astrophysical Journal. https://doi.org/10.3847/1538-4357/ab93c2
The Daily Galaxy, Max Goldberg, via NRAO
Image credits: Chandra X-ray Observatory at the top of the page and ALMA plate (ESO / NAOJ / NRAO), P. Cigan and R. Indebetouw; NRAO / AUI / NSF, B. Saxton; NASA / ESA