Not sure if you are asking for an explanation of how they measured the amount of dark matter, or if you're reading the title as claiming that dark matter has been proven to exist via this galaxy. I'll start with the former and then answer the latter.
Now, I don't know the specifics of this research and haven't been in STEM for over two decades, but I think I can still give a simplified "correct enough" explanation of the principles involved in these measurements.
Recall that gravitational pull is caused by space-time being curved due to mass. Gravity determines the paths of stellar objects, and can also bend light (known as gravitational lensing). Astronomers can "reverse that": make observations related to gravity, then determine how much gravity the observations require, then determine how much mass that requires.
Similarly, the amount of conventional matter in a galaxy (plus a few other things, like age) also affects how many stars you'd expect there to be, and how bright the galaxy should be. So astronomers found ways to use measurements of the brightness of the galaxy to estimate how much visible mass it must have, meaning how much conventional matter there is.
The interesting bit is that whenever we do both of these things, the estimated mass based on visible matter is always lower than the mass estimations based on gravitational effects. Which is why astronomers believe that dark matter exists.
And in the observed galaxy that is discussed in the article those two estimates are really far apart.
Now for the second interpretation: the title is a bit misleading there. The observations of this galaxy do not directly confirm that dark matter exists. It just has a discrepancy between visible matter and "gravitationally inferred" matter that is over 99%, and if the explanation for that is dark matter, then this galaxy consists of 99% dark matter. But you can probably imagine why the current headline is used as a shorthand for that.
However, that difference does speak in favor of dark matter existing. The main alternative theory for the observed matter/gravity discrepancy is that gravity may work differently at large scales (e.g. Modified Newtionian Dynamics or MOND).
One critique of MOND is that if it holds up, then it would imply we should observe the same discrepancy between gravity and observable mass everywhere in space. And we don't: there are galaxies with a lower discrepancy ("less dark matter"), and now this galaxy with a higher discrepancy ("more dark matter").
More Than Meets the Eye
Preliminary analysis indicates that CDG-2 has a total luminosity equivalent to about 6 million suns, with the four globular clusters contributing about 16 percent of that brightness, an unusually large share. This distribution suggests that, despite its low light, the galaxy is a gravitationally bound system, implying a particularly dense dark matter halo. Astronomers estimate that this invisible structure accounts for between 99.94 to 99.98 percent of CDG-2’s total mass.
According to current models, dark matter constitutes roughly 27 percent of the universe’s total energy density and about 85 percent of its matter. Although the exact nature of what makes up dark matter is still unclear, because it neither emits nor reflects light, scientists infer its existence from its gravitational effects on radiation, visible matter, and the large-scale structure of the cosmos.
Dark matter is so pervasive throughout galaxies that its presence explains the stability and motion of stars in systems such as the Milky Way. For example, current models indicate that our galaxy is embedded in a halo composed of about 90 percent dark matter.
However, the case of CDG-2 is extreme: a galaxy with almost no stars, surrounded almost entirely by an invisible halo. These types of systems, so-called “dark galaxies,” are beginning to appear in astronomical records. Beyond their rarity, scientists value them because they serve as natural laboratories for exploring the nature of dark matter and testing current models of galaxy formation.
So they proved the existence of dark matter, but no one knows about it yet because they only published it on a website with a paywall? Sorry, I call shenanigans on that.
I know, I just think it's funny (and pretty stupid) to reference something theoretical to prove something else. I don't think it works that way. That's like saying "I proved Bigfoot is real because the gnome that lives under my front stoop showed me where Bigfoot bit his pet dragon on the wing."
“The more important fundamental laws and facts of physical science have all been discovered…”
-Albert A. Michelson, 1894
Only a few years later, Albert Einstein developed relativity, Max Planck launched quantum theory... Both completely reshaped physics.
You never know what's going to be next. The fact that we're not anywhere close to a Grand Unified Theory suggests we may have everything wrong. Both exciting and depressing.
ASTRONOMERS HAVE JUST identified what appears to be a cosmic anomaly: a faint galaxy with so few visible stars that, according to calculations, as much as 99.9 percent of its mass is dark matter. The remaining 0.1 percent is conventional matter.
This galaxy, located about 300 million light-years away, is practically invisible. Only four globular clusters, small concentrations of stars that look like isolated neighborhoods in the middle of the void, stand out. For years, these star collections in the Perseus cluster were considered independent objects.
Candidate Dark Galaxy-2 is only visible through four globular clusters that contribute to 16 percent of its total brightness. Scientists believe 99.9 percent of this galaxy is dark matter. NASA/ESA
Now, after an exhaustive analysis, a study published in The Astrophysical Journal Letters presents solid evidence that these globular clusters are part of the same galaxy dominated by dark matter. Tentatively named CDG-2 (Candidate Dark Galaxy-2), it is the first galaxy to be detected only by its brightest fragments.
The authors pooled data from the Hubble, Euclid, and Subaru telescopes, three of the most powerful observatories available. The combined readings reveal an extremely faint glow around the four globular clusters. This residual light is a clear sign of an underlying galaxy so dim that the three telescopes missed it on their own.
More Than Meets the Eye
Preliminary analysis indicates that CDG-2 has a total luminosity equivalent to about 6 million suns, with the four globular clusters contributing about 16 percent of that brightness, an unusually large share. This distribution suggests that, despite its low light, the galaxy is a gravitationally bound system, implying a particularly dense dark matter halo. Astronomers estimate that this invisible structure accounts for between 99.94 to 99.98 percent of CDG-2’s total mass.
According to current models, dark matter constitutes roughly 27 percent of the universe’s total energy density and about 85 percent of its matter. Although the exact nature of what makes up dark matter is still unclear, because it neither emits nor reflects light, scientists infer its existence from its gravitational effects on radiation, visible matter, and the large-scale structure of the cosmos.
Dark matter is so pervasive throughout galaxies that its presence explains the stability and motion of stars in systems such as the Milky Way. For example, current models indicate that our galaxy is embedded in a halo composed of about 90 percent dark matter.
However, the case of CDG-2 is extreme: a galaxy with almost no stars, surrounded almost entirely by an invisible halo. These types of systems, so-called “dark galaxies,” are beginning to appear in astronomical records. Beyond their rarity, scientists value them because they serve as natural laboratories for exploring the nature of dark matter and testing current models of galaxy formation.
I think in this case dark matter is basically “unidentified mass”. We know it is something but don’t know what it is. Can’t detect it through anything other than gravitational effects.
Spare-Locksmith-2162 | 21 hours ago
How did they confirm the existence of Dark Matter?
vanderZwan | 11 hours ago
Not sure if you are asking for an explanation of how they measured the amount of dark matter, or if you're reading the title as claiming that dark matter has been proven to exist via this galaxy. I'll start with the former and then answer the latter.
Now, I don't know the specifics of this research and haven't been in STEM for over two decades, but I think I can still give a simplified "correct enough" explanation of the principles involved in these measurements.
Recall that gravitational pull is caused by space-time being curved due to mass. Gravity determines the paths of stellar objects, and can also bend light (known as gravitational lensing). Astronomers can "reverse that": make observations related to gravity, then determine how much gravity the observations require, then determine how much mass that requires.
Similarly, the amount of conventional matter in a galaxy (plus a few other things, like age) also affects how many stars you'd expect there to be, and how bright the galaxy should be. So astronomers found ways to use measurements of the brightness of the galaxy to estimate how much visible mass it must have, meaning how much conventional matter there is.
The interesting bit is that whenever we do both of these things, the estimated mass based on visible matter is always lower than the mass estimations based on gravitational effects. Which is why astronomers believe that dark matter exists.
And in the observed galaxy that is discussed in the article those two estimates are really far apart.
Now for the second interpretation: the title is a bit misleading there. The observations of this galaxy do not directly confirm that dark matter exists. It just has a discrepancy between visible matter and "gravitationally inferred" matter that is over 99%, and if the explanation for that is dark matter, then this galaxy consists of 99% dark matter. But you can probably imagine why the current headline is used as a shorthand for that.
However, that difference does speak in favor of dark matter existing. The main alternative theory for the observed matter/gravity discrepancy is that gravity may work differently at large scales (e.g. Modified Newtionian Dynamics or MOND).
One critique of MOND is that if it holds up, then it would imply we should observe the same discrepancy between gravity and observable mass everywhere in space. And we don't: there are galaxies with a lower discrepancy ("less dark matter"), and now this galaxy with a higher discrepancy ("more dark matter").
meekabo0131 | 29 minutes ago
thanks for such a good explanation
morganational | 2 hours ago
Came here to say this. Confirming dark matter is a much bigger deal than this bullshit.
JrYo15 | 19 hours ago
It explains it in the article
Inner-Boysenberry925 | 19 hours ago
Oh yeah, the paywalled article? The article that I can't read? That article?
elcapitan520 | 19 hours ago
More Than Meets the Eye Preliminary analysis indicates that CDG-2 has a total luminosity equivalent to about 6 million suns, with the four globular clusters contributing about 16 percent of that brightness, an unusually large share. This distribution suggests that, despite its low light, the galaxy is a gravitationally bound system, implying a particularly dense dark matter halo. Astronomers estimate that this invisible structure accounts for between 99.94 to 99.98 percent of CDG-2’s total mass.
According to current models, dark matter constitutes roughly 27 percent of the universe’s total energy density and about 85 percent of its matter. Although the exact nature of what makes up dark matter is still unclear, because it neither emits nor reflects light, scientists infer its existence from its gravitational effects on radiation, visible matter, and the large-scale structure of the cosmos.
Dark matter is so pervasive throughout galaxies that its presence explains the stability and motion of stars in systems such as the Milky Way. For example, current models indicate that our galaxy is embedded in a halo composed of about 90 percent dark matter.
However, the case of CDG-2 is extreme: a galaxy with almost no stars, surrounded almost entirely by an invisible halo. These types of systems, so-called “dark galaxies,” are beginning to appear in astronomical records. Beyond their rarity, scientists value them because they serve as natural laboratories for exploring the nature of dark matter and testing current models of galaxy formation.
quad_damage_orbb | 14 hours ago
Oh right, so it's a somewhat normal galaxy that just has a large amount of unaccounted mass? That makes sense I guess.
bob_in_the_west | 8 hours ago
>normal galaxy that just has a large amount of unaccounted mass
These two don't go together.
gregorydgraham | 9 hours ago
You da MVP!
Critical-Tomorrow-27 | 19 hours ago
Yeah that one
carterartist | 17 hours ago
it wasn't paywalled for me...
Medd- | 13 hours ago
Not OP but it was paywalled for me. There's a set number of articles you can read as part of a free trial.
carterartist | 8 hours ago
Gotcha
JrYo15 | 16 hours ago
It wasn't for me either, it may be region specific, or that redditor may just be full of shit
quad_damage_orbb | 14 hours ago
>Do your own research bro
Only research that is freely available is fox news and Joe Rogan
>No, not like that!
carterartist | 17 hours ago
time to check out archive.is....
ex1stence | 13 hours ago
Why do we even have that article??
vanderZwan | 11 minutes ago
I'm shocked that nobody else got the Emperor's New Groove reference
JrYo15 | 16 hours ago
I had no paywall, calling cap
morganational | 2 hours ago
So they proved the existence of dark matter, but no one knows about it yet because they only published it on a website with a paywall? Sorry, I call shenanigans on that.
JrYo15 | 2 hours ago
i legit still don't have a paywall. Some of you are having a regional problem.
In the article it goes over what and how they are classifying dark matter galaxies.
It seams they are operating from a point of luminosity an not foreign exotic matter
morganational | 2 hours ago
I know, I just think it's funny (and pretty stupid) to reference something theoretical to prove something else. I don't think it works that way. That's like saying "I proved Bigfoot is real because the gnome that lives under my front stoop showed me where Bigfoot bit his pet dragon on the wing."
AbyssDataWatcher | 8 hours ago
Gravity
Helldiver_of_Mars | 4 hours ago
The absense of matter. Just like knocking on a wall. You don't have to be in the wall to know it's hollow.
waffle299 | 18 hours ago
Well, this is going to be even more of a challenge for MoND...
alternatingflan | 14 hours ago
The more we know, the more we don’t.
I_am_a_fern | 13 hours ago
“The more important fundamental laws and facts of physical science have all been discovered…”
-Albert A. Michelson, 1894
Only a few years later, Albert Einstein developed relativity, Max Planck launched quantum theory... Both completely reshaped physics.
You never know what's going to be next. The fact that we're not anywhere close to a Grand Unified Theory suggests we may have everything wrong. Both exciting and depressing.
RestaurantFamous2399 | 12 hours ago
Or we are not wrong, and multiple things can be true at the same time.
silverwolfe2000 | 7 hours ago
ASTRONOMERS HAVE JUST identified what appears to be a cosmic anomaly: a faint galaxy with so few visible stars that, according to calculations, as much as 99.9 percent of its mass is dark matter. The remaining 0.1 percent is conventional matter.
This galaxy, located about 300 million light-years away, is practically invisible. Only four globular clusters, small concentrations of stars that look like isolated neighborhoods in the middle of the void, stand out. For years, these star collections in the Perseus cluster were considered independent objects.
Candidate Dark Galaxy-2 is only visible through four globular clusters that contribute to 16 percent of its total brightness. Scientists believe 99.9 percent of this galaxy is dark matter. NASA/ESA
Now, after an exhaustive analysis, a study published in The Astrophysical Journal Letters presents solid evidence that these globular clusters are part of the same galaxy dominated by dark matter. Tentatively named CDG-2 (Candidate Dark Galaxy-2), it is the first galaxy to be detected only by its brightest fragments.
The authors pooled data from the Hubble, Euclid, and Subaru telescopes, three of the most powerful observatories available. The combined readings reveal an extremely faint glow around the four globular clusters. This residual light is a clear sign of an underlying galaxy so dim that the three telescopes missed it on their own.
More Than Meets the Eye
Preliminary analysis indicates that CDG-2 has a total luminosity equivalent to about 6 million suns, with the four globular clusters contributing about 16 percent of that brightness, an unusually large share. This distribution suggests that, despite its low light, the galaxy is a gravitationally bound system, implying a particularly dense dark matter halo. Astronomers estimate that this invisible structure accounts for between 99.94 to 99.98 percent of CDG-2’s total mass.
According to current models, dark matter constitutes roughly 27 percent of the universe’s total energy density and about 85 percent of its matter. Although the exact nature of what makes up dark matter is still unclear, because it neither emits nor reflects light, scientists infer its existence from its gravitational effects on radiation, visible matter, and the large-scale structure of the cosmos.
Dark matter is so pervasive throughout galaxies that its presence explains the stability and motion of stars in systems such as the Milky Way. For example, current models indicate that our galaxy is embedded in a halo composed of about 90 percent dark matter.
However, the case of CDG-2 is extreme: a galaxy with almost no stars, surrounded almost entirely by an invisible halo. These types of systems, so-called “dark galaxies,” are beginning to appear in astronomical records. Beyond their rarity, scientists value them because they serve as natural laboratories for exploring the nature of dark matter and testing current models of galaxy formation.
theMEtheWORLDcantSEE | 15 hours ago
The Dark Galaxy? Like the dark side of the force where Siths are from?! Or Hell
Psittacula2 | 14 hours ago
*A Galaxy Composed Almost Entirely of “Dark Matterainium” Has Been Confirmed*.
Hmm does not trip off the tongue as well… sounds less plausible than “dark matter”.
stupide- | 4 hours ago
Well dark matter is only a theory, how can you confirm something made of theory ? That's how politics works, not science
VVynn | 3 hours ago
I think in this case dark matter is basically “unidentified mass”. We know it is something but don’t know what it is. Can’t detect it through anything other than gravitational effects.
Opusswopid | 11 hours ago
But does it have a Death Star at its center?