What If a Magnetar Collided With a Black Hole?

In the center of our galaxy, the Milky Way, there is a supermassive black hole feeding on nearby stars. It’s called Sagittarius A*. And if a giant gravitational monster slowly eating the galaxy isn’t terrifying enough, there is another cosmic monstrosity lurking around it.

Could they, one day, come a little too close and collapse on each other? What would be left of the Milky Way if they did? Would there be even a slight chance that the Earth could get out of that safely?

This monstrosity creeping through the Milky Way is a remnant of a giant, exploded star. But it’s not just any remnant. It’s an extremely dense and very magnetic collapsed stellar core — a magnetar.

Let me refresh your knowledge of magnetars. They are born when a star at least eight times more massive than our Sun reaches its expiration date, and explodes in a beautiful supernova.

Much of that star is gone, but the dense core of it remains. Most of these remnants become neutron stars. They spin very fast, usually a few times per second. And they are composed of neutrons.

Some neutron stars have such strong magnetic fields that they emit electromagnetic radiation from their poles. That makes them pulsars, and you can observe them with a telescope when their poles face the Earth.

Only a few such pulsars develop the extremely powerful magnetic field. They become the strongest magnets in the Universe, the magnetars. They spin once every ten seconds, but their magnetic field is a hundred times stronger than that of a neutron star.

If one of those magnets came halfway between the Moon and the Earth…well, you know, it wouldn’t be pretty. But would it be as bad from a distance of 26 light-years away?

What I’d like to know is, would a magnetar swallow a black hole, or would a black hole gobble up a magnetar? The collision of these two giants wouldn’t end up in an explosion, but in a quiet cosmic merger, stretched over billions of years.

Although magnetars are incredibly powerful, they would lose the battle with a black hole. Depending on the trajectory of the magnetar, as well as the size and mass of both the magnetar and the black hole, the magnetic monster would be eaten up either whole, or slowly, piece by piece.

As the magnetar was being torn apart by the black hole, it would be sending gravitational waves throughout the Universe, disturbing the curvature of spacetime. Once the black hole consumed the magnetar, its mass would increase and expand its event horizon.

Thanks to this expansion, more and more stars would be flung into its dark density. The black hole would be slowly eating our galaxy, star by star.

Sagittarius A* might already have a record of consuming neutron stars. Eventually, after quadrillions of years of star consumption, the black hole could gobble up the Milky Way, all of it. By that time, humanity would most likely be long gone anyway.

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