The answer largely depends on what we consider an “object” – in any case, there are inconceivably huge beasts in the universe. Beware, horrible numbers are coming!
The Universe is full of objects of gigantic mass – they have a mass that we cannot even fathom. However, it is very difficult to say which is the most massive object in the Universe, and there are two reasons for this: one is that it is difficult to define what can be considered an object at all, and the other is that we are discovering more and more things with increasingly better and more powerful telescopes. so if an object can get on top of the podium, another one can quickly push it off.
In the case of the most massive objects, two heavenly bodies can strike us from the get-go – since they are quite well-known, and we know about them that they have multiples of the mass of the most massive object in our star system, the Sun: these two candidates are therefore the neutron star and the black hole.
Let’s start with the neutron star! Stars with a significantly larger mass than our (otherwise average-sized) Sun end their lives with a supernova explosion. Depending on how big these stars are, two things can happen: the biggest ones explode under their own massive gravitational force and become smaller (stellar mass) black holes. The smaller ones, on the other hand, which are not massive enough to collapse into black holes, eventually transform into dense neutron stars.
As can be seen from the above, neutron stars are less massive than even smaller black holes, so let’s move on to these real, mysterious monsters! The mass of black holes is truly incomprehensible. Even the name of supermassive black holes in the core of galaxies suggests that their mass is more than respectable, but there are many different types of black holes. The most common are the smaller, so-called stellar-mass black holes mentioned above, the smallest of which have three times the mass and the largest twenty times that of our Sun.
That’s pretty significant, but it’s nothing compared to the supermassive black holes at the center of galaxies—these behemoths can be billions of times more massive than our Sun. To put this into context: the mass of the Sun is about 333,000 times that of the Earth (which is estimated at 13 billion trillion tons). To put it another way, about 1.3 million Earths fit inside the Sun. And if we think about a billion times this – that is, we try to think – then we can see that there can’t be many people who would really understand these dimensions and proportions.
Scientists still do not fully understand how supermassive black holes are formed, but according to current assumptions, there is one at the center of every galaxy, including our own, the Milky Way.
At the center of the Milky Way is Sagittarius A*, which has a mass about 4 million times that of the Sun. But it dwarfs the recently discovered M87*, which is about 1,000 times more massive than Sagittarius A* – despite being at the center of a galaxy only twice as massive as our own.
However, even M87* is a tiny dwarf compared to Phoenix A, which according to a 2016 study is the most massive black hole to date: Phoenix A is so massive that it has a mass equivalent to 100 billion solar masses and more may exceed the theoretical maximum for the size of black holes. By the way, the mass of these distant objects can be measured in two ways: on the one hand, the speed of the objects orbiting around them is measured, and on the other hand, the speed at which they feed on the gas surrounding them.
With this, in principle, we can close the question: the largest known object is Phoenix A. However, this is where the problem of definition, which has already been discussed before, comes into play: what do we mean by object?
These black holes are located in galaxies, and only a part of their mass is the black hole – so by definition they are more massive than these. So the question is, do we perceive a galaxy as a single object or as a randomly assembled group of stars, planets and black holes? When treated as a single object, even our own Milky Way, at about 800 billion solar masses, is far more massive than any black hole we know or are likely to ever find. However, the problem is that even with galaxies we do not necessarily get to the end of the question: what about the group of galaxies, for example the Local Group of Galaxies, which includes the Milky Way, or the Virgo supercluster, which also includes the latter?
And this list can be continued for a very long time, so there is no really precise answer to this question, and the answer depends on our perception, that is, on how long we think we can talk about an object.
(Source: IFLScience, Treehugger, Image: Pixabay/spirit111)