Perseus Cluster.  Credit: NASA, ESA, and Z. Levay (STScI)

Hubble Finds Evidence of Dark Matter Around Small Galaxies

Article Updated: 24 Dec , 2015

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The Hubble Space Telescope has uncovered a strong new line of evidence that galaxies are embedded in halos of dark matter. By looking at the Perseus galaxy cluster, Hubble discovered a large number of small galaxies that have remained intact while larger galaxies around them are being ripped apart by the gravitational tug of other galaxies. “We were surprised to find so many dwarf galaxies in the core of this cluster that were so smooth and round and had no evidence at all of any kind of disturbance,” said astronomer Christopher Conselice of the University of Nottingham, UK, and leader of the team that made the Hubble observations. “These dwarfs are very old galaxies that have been in the cluster for a long time. So if something was going to disrupt them, it would have happened by now. They must be very, very dark-matter-dominated galaxies.”

Observations by Hubble’s Advanced Camera for Surveys spotted 29 dwarf elliptical galaxies in the Perseus Cluster, located 250 million light-years away and one of the closest galaxy clusters to Earth. Of these galaxies, 17 are new discoveries.

Cosmologists estimate that dark matter comprises 23 percent of all energy in the cosmos. An equally mysterious “dark energy,” which drives galaxies apart, is thought to take up another 73 percent or so. The ordinary matter that we can see is believed to represent only four percent of the total mass of the Universe.

Because dark matter cannot be seen, astronomers detected its presence through indirect evidence. The most common method is by measuring the velocities of individual stars or groups of stars as they move randomly in the galaxy or as they rotate around the galaxy. The Perseus Cluster is too far away for telescopes to resolve individual stars and measure their motions. So Conselice and his team derived a new technique for uncovering dark matter in these dwarf galaxies by determining the minimum additional mass contribution from dark matter that the dwarfs must have to protect them from being disrupted by the strong, tidal pull of gravity from larger galaxies.

Galaxies in the Perseus Cluster. Credit: NASA, ESA, and Z. Levay (STScI)

Galaxies in the Perseus Cluster. Credit: NASA, ESA, and Z. Levay (STScI)



The dwarf galaxies may have an even higher amount of dark matter than spiral galaxies. “With these results, we cannot say whether the dark matter content of the dwarfs is higher than in the Milky Way Galaxy,” Conselice said. “Although, the fact that spiral galaxies are destroyed in clusters, while the dwarfs are not, suggests that this is indeed the case.”

But these new images provide evidence that the undisturbed galaxies are enshrouded by a “cushion” of dark matter that protects them from being torn apart.

Source: HubbleSite


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Anaconda
Member
Anaconda
March 12, 2009 1:45 PM
From the post: “The ordinary matter that we can see is believed to represent only four percent of the total mass of the Universe.” So, 96% of total mass is undetected…until now. From the Hubble site: “Astronomers have deduced the existence of dark matter by observing its gravitational influence on normal matter, consisting of stars, gas, and dust.” Translation: if “dark” matter didn’t exist, the gravity “only” model would be falsified.” From the Hubble site: “They must be very, very dark-matter-dominated galaxies.” Unless, of course, the “gravitational tides” have been over-stated. And, yet over in the Leo Ring things are much different: From Nature: “We speculate that the complexes are dwarf galaxies observed during their formation, but distinguished… Read more »
Anaconda
Member
Anaconda
March 12, 2009 4:50 PM

The Nature magazine published paper that discusses the Leo Ring is here:

http://www.nature.com/nature/journal/v457/n7232/full/nature07780.html

Todd Coolen
Member
Todd Coolen
March 12, 2009 1:15 PM

This is extremely exciting news.

Anaconda
Member
Anaconda
March 12, 2009 5:23 PM

@ ThereIsNoSuchThingAsMagic :

First off, you are assuming that “only” gravity can explain the “faster rotation than expected”.

And with that assumption, well, then, there has to be some kind of “dark” matter which has a gravitational effect.

But what if there is also the possibility of an electromagnetic effect?

Plasma physicists at the Los Alamos National Laboratory have produced a computer simulation based on data gained from plasma physics experiments, which demonstrates galaxy formation per electromagnetic principles.

http://www.plasma-universe.com/index.php/Galaxy_formation

Please note at the bottom of the linked webpage the published and peer reviewed papers that explain and support this theory of galaxy formation.

Anaconda
Member
Anaconda
March 12, 2009 6:43 PM
@ ThereIsNoSuchThingAsMagic: Apparently, you couldn’t bring yourself to verify the authority at the bottom of the webpage I linked to. That reveals your bias & prejudice which have no place in science. Take a look at the bottom of the home page for the Plasma Universe website. http://plasmascience.net/tpu/TheUniverse.html See, “Our Sponsors and Associates:” Department of Energy National Science Foundation Los Alamos National Laboratory Plasma International Dupont Air Force Office of Scientific Research IEEE (The Institute of Electrical and Electronics Engineers) Nuclear And Plasma Sciences Society (association identified at upper left-hand corner of homepage website), 360,000 members. All these organizations support Plasma Universe theory. They all have evaluated the scientific observations & measurements that support Plasma Universe theory. The… Read more »
Anaconda
Member
Anaconda
March 12, 2009 8:17 PM

@ ThereIsNoSuchThingAsMagic:

Calvin said it pretty well.

If I misinterpreted your intent and meaning, which you are indicating, I sincerely apologize.

I’m sorry for my reaction, but, yes, I have been subjected to abuse for expressing my opinions on this website, and I suppose that has left me a little touchy — and regrettably liable to misinterpret, which I did in response to your comment.

Again, I’m sorry and I apologize.

Xzr Xza
Guest
Xzr Xza
March 12, 2009 3:01 PM

I agree to an extent with this very intelligent Anaconda. Assume that dark matter is heavily enshrouding these galaxies enough to resist obliteration by larger galaxies- then wouldn’t that mean they were imparted this large amount of dark matter by galaxies previous to these dwarfs? So that would mean that their dark matter content would be determined by the amount around during their formation, and how much of it they managed to snatch up…
Right?
But seriously though, odd inconsistency. I’m going to go look at the article now. Er. Wherever it is.

Calvin
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Calvin
March 12, 2009 10:04 PM
ND/Others: Blehk! >.< Let’s not bring those extremely lengthy and off-topic “debates” in to this. Honestly, what consitutes a “personal comment” is highly debatable and I don’t think Anaconda is by any means the only person to have made them. Olaf: “Dark matter is a mix name of different things, some parts could be neutrino’s, some other could be black holes or brown dwarfs. These are not really detectable if they are out there at this distance. ” This raised an interesting question for me. I guess the most fundamental definition of “dark matter” is simply matter which isn’t detectible through its radition. Is there any way that could include black holes, which obviously are, indeed, a bit… Read more »
David R.
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David R.
March 12, 2009 3:22 PM

At the very least, there is a possibility (or perhaps a probability) of something preserving their shape. Call it what you will, there is the possibility (or probability) that something exists that’s yet to be understood, dammit.

Calvin
Guest
Calvin
March 12, 2009 7:16 PM
ThereIsNoSuchThingAsMagic: Unfortunately I think your “thank you for your time” came off as sarcastic :O that is why Anaconda reacted as he did. One must always watch sarcasm vs. non-sarcasm on the internet… I know from too much personal experience that it is difficult when we are dealing with text! Anyway, I’m glad people are able to have a good scientific discussion on this blog and hope such discussions continue. Personally (and noting that I am only an amateur scientist) I am tentatively in favor of dark matter stuff, although of course I recognise there is still alot about the universe we don’t understand. One of the bests parts about this article about the article in my opinion… Read more »
GekkoNZ
Member
March 12, 2009 4:48 PM

Anaconda, you go into some detail about how dark matter doesnt exist and how the “gravity only” model is incorrect, and from your post it sounds like you have knowledge in this field. So how do you explain the observed gravitational effects that we see in galaxies i.e. the faster rotation than expected, and other observed effects that appear to be caused by mass that does not interact via electromagnetic radiation ?

GekkoNZ
Member
March 12, 2009 5:02 PM

Im sorry anaconda, but i have to pay to view that article, so im unable to read it. The site says “To read this story in full you will need to login or make a payment (see right).”

But from reading the abstract, it doesnt seem to answer the question i asked you.

It seems that you dont accept the current ‘dark matter’ explanation that the majority of scientists in the field have shown, so im just curious as to what theory you are basing your ideas on. Can you please elaborate?

ZomZom
Member
ZomZom
March 12, 2009 5:10 PM

I’d like to know how this data correspond with John Moffat’s Modified theory of Gravity (MOG). If MOG does not fit this finding, then a more-helpful headline would be appreciated. Otherwise, a bias toward dark matter is evident.

GekkoNZ
Member
March 12, 2009 5:35 PM

Plasma Cosmology…..

Thank you for your time Anaconda.

Marco
Member
March 12, 2009 6:22 PM
This thought struck me recently concerning dark matter (DM). The 4% of matter that we can see is made up of various types of particles, or different types of matter to put it another way. DM is said to comprise 23% of all matter, or almost six times the amount of ordinary matter. Why do we think that DM is one thing? Why couldn’t it be a variety of things that share similar properties? I have seen a number of candidates including WIMPs, carbon dust, MACHOs, neutrinos just to name a few. If Dr. Sommerfeld’s tachyons exist, would they have a gravitational effect and be bound by gravity? Again, if they exist, in what proportion to ordinary matter… Read more »
GekkoNZ
Member
March 12, 2009 6:47 PM
That could well be the case Marco… currently, it would be of enormous help just to confirm one of those sources…but once we have a foothold, it will narrow down ( or complete ) the search. It kindof reminds me of the time just before Einstein came out with his papers on relativity….physicists at the time thought they had the laws of nature fully discovered and sorted…there was just that pesky phenomenon of the piezoelectric effect to be figured out…and the rest, as they say…is history. I suspect our discovery of what dark matter ( and dark energy ) really is will be the dawn of a new age of understanding of reality. I just hope i live… Read more »
GekkoNZ
Member
March 12, 2009 6:51 PM

Anaconda: What the hell are you on about? I simply asked you what theory you were basing your ideas on, and you gave me the answer. Question asked, question answered, nothign else was said. Bloody hell man,what else do you want me to say?

You jump to conclusions about bias and all that rubbish, when all i said was thanks for your time….chill out dude!!

geez, no wonder people here have so much bad stuff to say about you…yikes!! Take a chill pill….

Jon Hanford
Member
Jon Hanford
March 12, 2009 6:54 PM
After reading the original paper & studying the accompanying images, I see no reason that these dwarf galaxies couldn’t be the tidally-stripped remnants of what were once larger, old galaxies in the cluster. This would still be consistent with high concentrations of dark matter. Notice also that all 4 dwarfs contain a bright, star-like nucleus. It’s really remarkable that these ancient galaxies still exist at all in this huge, swarming galaxy cluster and have not succumbed to galactic cannibalism. (BTW, comparing the newly discovered dwarf galaxies in the Leo Ring and the dwarfs in the Perseus Cluster is sorta apples and oranges. The galaxy group associated with the Leo Ring is under a dozen galaxies strong while Abell… Read more »
GekkoNZ
Member
March 12, 2009 7:48 PM

Yeah, maybe i used the wrong font or something…but still, talk about being a bit high strung…

I was actually being polite, because he obviously spent some time getting the info for me, but next time ill just not reply.

Myself, i just go where the evidence points, because you can do no less when searching for the truth about things. Ive only started reading about plasma cosmology, and havent read enough of the pros and cons of its theory to make an informed decision yet compared to dark matter theory…but im not going to let the likes of Anaconda cloud my judgment.

Olaf
Member
Olaf
March 12, 2009 8:15 PM

I am wondering if a massive black hole in the core cannot answer this.

First of all, these are old galaxies, so the black hole might have enough time to get bigger. Also these dwarf galaxies are really small, so the gravitational gradient is higher keeping the stars within a certain limit.

Then again, these are older galaxies, so they migth have attracted more dark matter since they are older too.

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