#m87

Messier 87 is a supergiant elliptical galaxy in the constellation Virgo that contains several trillion stars. One of the largest and most massive galaxies in the local universe,it has a large population of globular clusters—about 15,000 compared with the 150–200 orbiting the Milky Way—and a jet of energetic plasma that originates at the core and extends at least 1,500 parsecs (4,900 light-years), traveling at a relativistic speed. It is one of the brightest radio sources in the sky.

there's this thing called "multimessenger astronomy," where basically, instead of looking at things in the visible light spectrum all the time, we have multiple ways of observing an event in space. you guys have probably all seen the first-ever image of the event horizon of a black hole (M87) in 2019:

but, direct imaging is HARD. real hard. especially for objects like black holes, where light is bent so much that it cannot escape the spacetime curvature. however, M87's black hole is spinning! meaning, gravitational waves (like, ripples in really tightly stretched fabric), are traveling through spacetime and eventually reaching us.

you cannot see gravitational waves in visible light, but if you have a laser interferometer, like, say.... LIGO (Laser Interferometer Gravitational-Wave Observatory) from Caltech and MIT, then you can detect these gravitational waves and confirm the existence of this black hole. (in fact, this is how we confirmed that black hole mergers really were a thing!)

now, that was kind of a side tangent, so back to what I wanted to talk about: if Betelgeuse, the closest red supergiant to Earth, were to go supernova tomorrow, we would be able to see it in visible light eventually. we would be able to detect the gravitational waves from the event a few hours before the light reaches us, and so folks at LIGO could inform telescope operators all around the world that there would be a supernova for us to see soon.

however, even faster than this is if we detect neutrinos from a supernova. this is the cool part!! neutrinos are small and weakly interacting, so they are very efficient in taking excess energy out of a supernova and zooming away with it. since supernovae are HIGHLY energetic events, you will have SO MANY (like, on the order of 10^58) neutrinos escaping the explosion.

there are a few neutrino detectors that are active right now, and many in the making. one of the most prominent ones is IceCube. IceCube definitely warrants its own post, so I won't go into it just now, but it is what it sounds like.

literally :)

these energetic neutrinos would reach us around the same time the gravitational waves would, but it wouldn't be an event that is easily confused with another thing. few events in space create so many neutrinos, and spikes in the amount of neutrinos detected, along with confirmation from LIGO, would inform you, with nearly dead certainty, that you would be about to see a supernova with a telescope.

which is sooo freaking cool! we don't understand a lot about neutrinos yet (especially not me), because they are so small and weakly interacting. however, the fact that they can inform us greatly about events happening in the universe makes them very valuable mailmen for cosmic events.

Black holes with accretion disks do give off some angbang energy with all that fierce fire and energy enthusiastically swirling around a massive, mighty, and deep dark center of attention.

Image: Messier 87 as imaged by the Event Horizon Telescope | CC-BY 4.0

Post it for fun, why not