How do you make a galaxy without dark matter?

  • How do you make a galaxy without dark matter?

How do you make a galaxy without dark matter?

Luckily, their studies might be given an early boost as Hubble images of 23 other ultra-diffuse galaxies seem to suggest that three of them are similar to NGC 1052-DF2.

'So finding a galaxy without it is unexpected.

Dark matter and dark energy comprise the rest, and scientists have yet to directly observe either.

Astronomers have discovered a unique galaxy, from which dark matter appears to be completely missing. The galaxy is as large as our Milky Way, but it had escaped attention because it contains only 1/200th the number of stars. Another idea, first proposed more than two decades ago by Yale astronomer Priyamvada Natarajan, suggests that galaxies like NGC 1052-DF2 may form from galaxy-sized gobs of gas clumping together in jets ejected by feasting supermassive black holes. What they found shocked them: The clusters were hardly moving at all. However, just recently they observed a galaxy without dark matter, which brought even more confusion to them, given that dark matter makes up so much of the mass of the universe. "The standard paradigm has gas falling into halos - or lumps - of dark matter and turning into stars to make a galaxy", he said.

We don't really know what dark matter is and why it exists... or why it doesn't. "So finding the opposite, namely an absence of dark matter, really came out of the blue for us", he said.

The research was published online in the journal Nature.

Now, while using a new telescope, known as the Dragonfly Telescope Array, astronomers looking for faint, hard-to-find objects out in the universe, have found what they call an "Ultra-Diffuse Galaxy", named NGC1052-DF2 (DF2 for short), which has them scratching their collective heads.

In fact, it is so thinly populated that scientists can see right through it to galaxies behind it.

For Mack, the most exciting aspect of this galaxy is its potential to prove that dark matter - until now widely theorised but not directly observed - is real.

Dark matter is an invisible and mysterious substance that is thought to be crucial to the formation of galaxies. But how it formed is a complete mystery.

Speculative explanations include that a collision or cataclysmic event within the galaxy resulted in all the dark matter being swept away.

"The hunt is on", van Dokkum said. It does not look like a typical spiral galaxy, but it does not look like an elliptical galaxy either.

The observation also raises questions about how galaxies formed in the first place.

"It is conventionally believed to be an integral part of all galaxies, the glue that holds them together and the underlying scaffolding on which they are built", said co-author Allison Merritt from the Max Planck Institute for Astronomy, in Germany.

This is certainly not the case with the other galaxies.

Speaking with Space.com, Pieter van Dokkum of Yale University explained that for a galaxy with a star mass of 200 million solar masses, the "normal" would be 80 billion solar masses of dark matter. It appears to contain virtually no dark matter.

"Paradoxically, the presence of NGC1052- DF2 might misstate options to dark issue", the writers end, keeping in mind that those choices consist of both variants of MOND and also emergent gravity.

"I find this unlikely in all possible contexts", said McGaugh, who is a proponent of a "modified gravity" theory that excludes the existence of dark matter altogether. One suggestion is that the gas obtained focused as it was being expelled from a galaxy merging; an additional is that it created from issue gushed out by quasars.

Still, van Dokkum pointed out, his study was based only on the movements of the 10 globular clusters in this galaxy because those were all that were available.