In the center of the heart of our galaxy lives a supermassive black hole that we know as Sagittarius A* and of which, recently, we were able to see images and a realistic simulation of it. A black hole is an extremely dense object in space from which no light can escape.
These very mysterious and exotic objects are a key consequence of how gravity works: when a large amount of mass is squeezed into a small enough space, the resulting object rips through the very fabric of space and time, becoming a singularity. The gravity of a black hole is so powerful that it can attract all kinds of nearby material and “eat” it.
Astronomers know that in most galaxies, a black hole resides at their center but… what would happen if, hypothetically, this supermassive black hole with a high power of gravitational attraction disappeared?
Eliminating Sagittarius A* from the center of the galaxy
Would we plunge into a stage of galactic chaos in its absence? Would it pulverize the solar system as we know it? Nothing is further from reality. The expert astrophysicist in black holes at the University of Oxford, Becky Smethurst, explains that the truth is that the Milky Way would hardly even realize that the supermassive black hole at its center had disappeared. There would be no cataclysm in the galaxy.
The immense gravity of supermassive black holes also distorts space itself , so it is possible to see the influence of an invisible gravitational pull on stars and other objects. Everything would suggest that “supermassive” black holes, which can weigh millions or billions of times the mass of the Sun and can take less than a billion years to reach a very large size, and which have this tremendous force in our cosmos, would represent a significant change in the modus vivendi of the galaxy in which they exist.
The short answer: no.
In the event that the supermassive black hole disappeared… not much would happen. Everything would work as usual… as if it had never existed . Wouldn’t there be gravitational effects? They would be minimal, since the Milky Way has about 1,000,000,000,000 solar masses, so, in short, the total gravitational consequences would be minimal. And it is that the mass fraction of the black hole compared to that of the rest of the galaxy is insufficient.
The biggest effect would be on stars near the center of the galaxy (for which most of the gravity of the Milky Way stars cancels out fairly evenly, so they mostly feel the pull of the center). These stars, as the black hole disappears, would move in whatever direction their current orbit is headed; they would scatter. However, once we get a little further away from the galactic heart, the effect of Sagittarius A* is quite small in the grand scheme of an entire galaxy. Most of the stars in the galaxy would not even know that this compact radio source had vanished. Everything would continue spinning as usual.
It would be different if what disappeared from our galaxy was our star, obviously. Without the Sun, there would be nothing to support their orbits on that journey around the star. Without going any further, the Sun, that spherical figure composed mainly of hydrogen, represents 99.86% of the mass of our solar system (around 330,000 times that of the Earth).
And if you have ever wondered if it would be possible for a black hole to ‘eat’ a galaxy, we have the same explanation for this question. The gravitational reach of supermassive black holes, although titanic, is not great enough to ‘gobble up’ an entire galaxy.
Referencia: Black hole versus cosmological horizon entropy Tamara M. Davis (1), P. C. W. Davies (2), Charles H. Lineweaver (1) ((1) University of New South Wales, (2) Macquarie University, Australia) DOI: https://doi.org/10.1088/0264-9381/20/13/322
NASA 10 questions you might have about black holes, Elizabeth Landau.
Youtube channel: Becky Smethurst, astrophysicist at the University of Oxford
