Neutron star and Manhattan, which is bigger or smaller?
Summary: Magnetic superars emit up to 100 trillion times the energy of the Sun in about a tenth of a second during an eruption. Such events are very rare, and studying this phenomenon can give us a lot of insight into the interior of neutron stars and their magnetic fields.
A work depicting magnetic superflars, erupting spectacular energy from the surface of a neutron star. Image copyright source: NASA (United States Aeronautics and Space Administration)/Goddard Space Flight Center
As someone who deals a lot with the phenomena of destruction in astronomy, many people ask me, what is the phenomenon in the universe that scares me the most? Asteroid impact? Solar flares? A black hole that is unpredictable?
None of them, far from it. My answer is magnetic superflecks.
Why, you ask? So I tell you, a recently observed magnetic superfoar, in an explosion of about 1/10th of a second, spewed out the equivalent of 100 trillion solar energies.
！！！
This phenomenon was observed by NASA's Fermi satellite, which is used to detect cosmic rays. These are the highest forms of energy of light, and can only come from violent events of astonishing energy: stellar explosions, black holes devouring matter, and so on.
NGC 253, a lateral spiral galaxy about 1.1 million light-years from Earth (Image copyright source: Adam Bullock/Mount Lemmon Astronomical Center/University of Arizona)
Gamma-ray bursts were observed on April 15, 2020, and were quickly identified as coming from NGC 253, a lateral spiral galaxy about 1.1 million light-years from Earth. For galaxies, this distance seems to be very close, but there is still a long way to go from Earth... Even from such a long distance, Fermi could easily detect the radiation generated by this event.
Previous such eruptions have only been observed 3 times: twice in our Milky Way (1998 and 2004) and once in our satellite galaxy, the Great Magellanic Cloud (1979), 160,000 light-years from Earth.
A work depicting the magnetic field around a neutron star. Image copyright source: Kathy Reed / University of Pennsylvania
I once wrote about that outbreak in 2004, and everything panicked me. The bursts of gamma rays were so intense that the detectors of several astronomical satellites were at full capacity at the same time, and the Earth's magnetic field sounded, while also having a physical effect on our atmosphere, partially ionizing the upper layers of the atmosphere.
Notice that SGR 1806-20, the magneto star that erupted in 2004, is 50,000 light-years away, about half the diameter of the Milky Way. Still, it can cause us these problems.
So, yes, magnetostar freaked me out.
[Note: I know a lot of people get frightened by things like this, so I've noticed that, as far as we know, no magneto star is capable of producing huge flares close enough to us, causing severe damage.] They only scare you when you think about it. Actually, I'm more worried about larger solar events than cold ones like the magneto explosion. ]
What is the driving force behind all this chaos? A magnetostar is a type of neutron star that is the super-dense remnant of the core of a massive star after forming a supernova. When the star explodes outside, the core collapses. If it is massive enough, it will form a black hole, but if its mass is 1-3 times that of the Sun, it will be compressed into a neutron ball that is only a dozen kilometers wide. Think about it: the mass of the entire star is pressed into a city-sized sphere. It's incredible.
There's something even more amazing. The gravity of the neutron star's surface may be 1 billion times that of Earth, but even then it is dwarfed by a magnetic field that can be 1,000 billion times the strength of Earth. Except for those we call magnetostars, this magnetic field is rare. Their magnetic strength is so high that it affects everything around them even more than the incredible force of gravity.
But when you combine the two, things become as terrible as the end of the world.
Neutron stars are incredibly small, and at the same time have super high densities, and they can compress the entire sun into a ball of just a few kilometers. The work depicts a neutron star contrasting to Manhattan. Image copyright source: NASA (Nasa) Goddard Space Flight Center.
These magnetic fields exist in the crust of neutron stars and originate deep within the star's interior. Sometimes the crust moves, similar to the movement of the earth's crust during an earthquake, which is called a stellar earthquake for neutron stars. The energy involved in this vibration is enough to shake your soul.
Remember that neutron stars have 1 billion times the gravity of Earth, so throwing marshmallows onto the surface of a neutron star releases as much energy as a properly sized nuclear bomb. But at the same time, the crustal density of stars is very high, so the mass of moving in stellar earthquakes is also enormous. Although the Earth's crust may have moved only a centimeter, the seismic energy released is enormous, billions of times or more than the Sun's output.
This, in turn, triggered a violent vibration of the magnetic field that stored a large amount of energy. Together, these resulted in a catastrophic burst of energy: a magnetic superflint, an event equivalent to the entire energy output of thousands of galaxies.
A huge stream of plasma roared out of the magnetar, moving at a speed equivalent to the speed of light. While the initial burst may last only a fraction of a second, the plasma continues to emit high-energy radiation until it expands, cools, and declines.
At the very least, that's what we think is happening. The details are a bit unclear. Part of the problem is that only a small fraction is observed (magnetic superlashes that occurred in 1998 and 2004 are difficult to observe because they are too bright in gamma rays). We hope to get some help from studying the NGC 253 incident.
Magnetostars are very rare; we've only found 29 in the entire Milky Way, and only a small percentage of them have had these phenomena (maybe more magnetostars have erupted, but it's hard to observe them because the events are so rare). ）
I have two opinions on this matter. One is that they're too rare, and it's a terrible thing; these are fascinating events that can give us more insight into the interiors of neutron stars and their magnetic fields. We know they're also the source of fast radio wave bursts, but we don't know much about them, so it would be pretty cool to figure out the connection.
Another view is that their rarity is a blessing for us. I wish we didn't see too many magnetic superflabies! Or even if there were, hopefully they came from other galaxies and had no place for humans to live. I think that's more reasonable.
BY: Phil Plait
FY: Fuuin
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