Mysterious ‘ghost’ galaxy with no dark matter puzzles astronomers

It may not look like much, but this giant, fuzzy blob of a galaxy has astronomers perplexed.

The galaxy, called NGC 1052-DF2, or DF2 for short, contains virtually no dark matter.

“Finding a galaxy without dark matter is unexpected because this invisible, mysterious substance is the most dominant aspect of galaxies,” lead author Pieter van Dokkum of Yale University said.

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Could dark matter have existed before the big bang?

Tau.Neutrino said:

Could dark matter have existed before the big bang?

Um, next question. OK, I’ll have a go at an answer.

Dark energy could have existed before the big bang, in the eternal inflation multiverse it probably did. But dark matter is an entirely different kettle of fish.

All we know so far about the nature of dark matter is that every proposed explanation has already been disproved.

If dark matter is made of WIMPs then the simple anrwer is “no”. The universe after the big bang and before inflation was too small to contain even one WIMP.

On the other hand if dark matter arises from the f® model of gravity then the answer is possibly yes. I don’t believe that the f® model of gravity has a hope in hell of being correct, but you did ask.

This of course begs the question of whether time as we know it could have existed before the big bang.

mollwollfumble said:

Tau.Neutrino said:

Could dark matter have existed before the big bang?

Um, next question. OK, I’ll have a go at an answer.

Dark energy could have existed before the big bang, in the eternal inflation multiverse it probably did. But dark matter is an entirely different kettle of fish.

All we know so far about the nature of dark matter is that every proposed explanation has already been disproved.

If dark matter is made of WIMPs then the simple anrwer is “no”. The universe after the big bang and before inflation was too small to contain even one WIMP.

On the other hand if dark matter arises from the f® model of gravity then the answer is possibly yes. I don’t believe that the f® model of gravity has a hope in hell of being correct, but you did ask.

This of course begs the question of whether time as we know it could have existed before the big bang.

Thanks for that.

The dragon fly telescope which looked at the ghost galaxy is interesting, Now has an array of 48 lenses.

Dragonfly Telephoto Array

Astronomers Invent New Telescope By Tying Telephoto Lenses Together

At the other end of the scale.

Massive galaxy discovered made almost entirely of dark matter

Using the W. M. Keck Observatory and the Gemini North telescope — both on Maunakea, Hawaii — an international team of astronomers has discovered a massive galaxy that consists almost entirely of dark matter. The findings are being published in The Astrophysical Journal.

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Dang autocorrect. Not f® but f ( r ).

Now, as to the ghost galaxy, it’s already known that galaxy collisions can strip a small galaxy of its dark energy.

I need to look up the dark matter concentration of globular clusters. Hmm, not quite trivial, the dark matter concentration seems to vary with age at formation.

Ah, here we are, “globular clusters are normally considered to be almost devoid of dark matter” from wikipedia.

Tau.Neutrino said:

At the other end of the scale.

Massive galaxy discovered made almost entirely of dark matter

Using the W. M. Keck Observatory and the Gemini North telescope — both on Maunakea, Hawaii — an international team of astronomers has discovered a massive galaxy that consists almost entirely of dark matter. The findings are being published in The Astrophysical Journal.

more…

Yes. I’ve struck that before. The galaxies with the highest concentration of dark matter tend to be the dwarf irregulars.

Thanks for drawing my attention to the dragonfly telescope. From Canada, which is why I hadn’t heard of it.

> At the moment we only know its older than 10 billion years, but we’d like to know if it’s 10 billion years old or 13 billion years old.

As you’ve no doubt realised, the smart money is on 10 billion years.