From the abstract: “This is the lowest-mass object known to us, by two orders of magnitude, to be detected at a cosmological distance by its gravitational effect. This work demonstrates the observational feasibility of using gravitational imaging to probe the million-solar-mass regime far beyond our local Universe.”
Can someone knowledgeable weigh in: is the "dark object" here believed to be a localized blob of dark matter? A dark star or black hole? Or is "dark" being used generally to mean "not bright enough to see at this distance"?
In this context, “dark object” really does mean a localized blob of dark matter, not a black hole or a dim, normal-matter object.
The research team detected it only through its gravitational lensing effect — the way it slightly distorted the light from a more distant galaxy. There’s no emission at any wavelength (optical, infrared, or radio), and its gravitational signature matches a million-solar-mass clump of invisible mass rather than a compact point source like a black hole.
They specifically interpret it as a dark matter subhalo — one of the small, dense lumps that simulations of “cold dark matter” predict should pepper the universe’s larger halos. It’s too massive to be a single star, far too diffuse to be a stellar remnant, and not luminous enough to be a faint galaxy.
So “dark” here isn’t just shorthand for “too dim to see at this distance” — it’s used in the literal physical sense: matter that doesn’t emit or absorb light at all, detectable only via gravity.
Eventually, all the dark matter clumps into rings around galaxies, but since this one is so distant, ~10B light years, so we are seeing that clump as it was that long ago before it difused into it's ring shape we can see in the galaxies around us.
Dark in the context of astrophysics means specifically that the object/matter does not interact directly with electromagnetic radiation (eg absorb an optical/microwave/radio photon). So it is probably dark matter, but probably unlikely to be a black hole because we can typically detect a black hole's effects in an indirect manner :P
From the paper, it could be the dark-matter halo of an otherwise too faint dwarf galaxy. They state that a “more definitive statement on what type of object [it] is will require deep optical/infrared observations to detect any potential EM emission”.
Definitionally, yes. It’s inert but lenses light around it.
The paper is more about the technical achievement of detecting it, IIUC. It’s not the first dark matter inference we’ve had, and doesn’t really tell us anything new about the stuff.
It challenges warm dark matter and ultralight dark matter theories because they'd be less likely to clump into something so small. Similarly MOND would have trouble explaining a completely isolated chunk of it like this.
They found a statistical anomaly that they're trying to atrribute to new physics, using some novel maths. So a tiny speck of evidence towards a new theory of matter (i know nothing about astro, just my supposition)
I'm an amateur but I feel confident enough to answer -- hopefully not a mistake!
They're explicitly looking for "Dark Matter", which doesn't "interact" with normal ("baryonic") matter or electromagnetic radiation (e.g. light). So it's not a black hole for sure, as those are composed of regular ol' matter.
RE:"dark star", that's really up in the air, I'd say! AFAICT the only academic reference to that term is for normal stars influenced by dark matter[1], but kinda the whole problem here is that we don't know much about what dark matter is composed of or into. Certainly it's not going to be a star in the traditional sense as it can't emit light, but I'm not aware of any reason this object can't end up being a giant sphere.
FWIW, Wikipedia says "One of the most massive stars known is Eta Carinae, with 100–200 [solar masses]", whereas this object "has a mass that is a million times greater than that of our Sun". If we're going to use metaphors, I think "dark dwarf galaxy" might be more appropriate?
I was always surprised that when we talk about BHs mass, charge, and spin that we really mean U(1) (electromagnetic) gauge charge and not charges from global symmetries. (If BHs had global charge, you could at least say that this or that black hole was made out of N baryons, or whatever.)
But it's really so---according to GR, black holes don't have global charges. So even if you see a star made out of baryons collapse into a black hole, once the BH settles down into a steady state you can't say it's "really" got baryons inside: the baryon number gets destroyed.
(Of course, a different model of gravity that preserves unitarity might upset this understanding.)
which doesn't "interact" with normal ("baryonic") matter
I think you mean it doesn't interact electromagnetically with either matter or radiation. It does interact with normal matter via gravity -- that's pretty much the strongest (only?) argument for its existence.
I'm not aware of any reason this object can't end up being a giant sphere
AIUI, most theories posit that solid spheres of dark matter are very unlikely because matter accretion is governed by electromagnetism in addition to gravity, and dark matter is not supposed to obey the former. Most models assume that dark matter is organized in gaseous clouds (halos); strictly speaking that's still a giant sphere, just not in the same way that Jupiter or the Sun or even the Oort Cloud is.
This confused me too from all those solar object size comparisons I’ve seen. Turns out there are stars that are 1000s of times bigger than the sun, but they aren’t the same density.
I'm unaware of any stars in the 1000 Msun range. Wikipedia puts 291 Msun of R136a1 at the largest. After that, 195 M of R136a2 is the next. A star at 100 Msun would be in the most massive stars known.
Is this the first time this article author has seen “image” used like this? We image human anatomy the same way - sophisticated algorithms take the output of CT, ultrasound, MRI and build something we can interpret visually.
Yep, this still blows my mind, has a radius of 330 million light years, of, er, nothing (well 60 galaxies compared to what should be several thousand). https://en.wikipedia.org/wiki/Bo%C3%B6tes_Void
We are surrounded by dark objects, a rock is a dark object, exoplanets are dark objects, and so are black holes. Pretty much everything but stars are dark objects. They are all dark because they don't emit light.
Here, I think they mean stuff (whatever it is) that can only be detected by gravitational lensing, and it makes sense that it has to be extremely heavy, because gravity is so weak.
I'm not a physicist but every definition of dark matter that I read says it does not interact with electromagnetic radiation hence it is invisible, and rocks are not that dark matter (wiki. NASA, etc)
So how do we know that these "dark matter objects" aren't actually just massive collections of normal matter that is dim enough and at such a far distance that it would appear (angular resolution-wise) to be invisible, but we can still detect the lensing?
> ... every definition of dark matter that I read says it does not interact with electromagnetic radiation ...
Actually, dark matter does interact with electromagnetic radiation -- it can deflect it, as in the case of gravitational lensing. But dark matter doesn't either emit nor absorb electromagnetic radiation directly.
We only know about dark matter because of its gravitational effects.
They are much lighter than 1 million solar masses and we know a few of them, with a variety of ways to detect them, including companion stars orbiting around them and gravitational waves during mergers.
Black holes fit the definition of dark matter, as they neither emit nor absorb electromagnetic radiation, not in a way that could be detected anyways. This is the "MACHO" theory of dark matter, which is not the favorite, but it is still taken seriously. Stellar mass black holes have been ruled out, I think, but it doesn't mean dark matter can't be made of black holes. In fact, primordial black holes are a rather hot theory.
If you think that's crazy, it's likely a drop in the bucket comared to the noumenonal world.
There's no reason to think that our senses encompass the vast majority of understanding everything in reality and current evidence that they, in fact, do not, via dark matter as a primary source.
I suspect our senses encompass a meaningless fraction of the noumenon.
It's that it demonstrates that some sort of noumenon can likely have partial but not 'full' overlap as we understand it with a phenomenon.
To elaborate, the noumenon can have properties that are unknown to us and outside the purview of certain senses (if not all) but still have partial phenomenal effects such as gravitational effects.
Given partial overlap, we could, and likely should, surmise that overlap, if partial, can also be zero. In fact, partial overlap with certain things (such as the gravitational field) but no sensory experience is exactly what we'd predict if this were true.
The mistake is thinking I'm asserting that things are phenomenon or noumenon when that's not quite right. Mostly, the supposition is that things can exist and have either 'full' (unlikely I think), partial, or zero overlap with our sensory experience. Things that demonstrably have partial overlap suggest a wider world of things. I simply find the idea that our evolved sensory experience encompass even a sizable fraction of reality to lack epistemic humility.
It's our descendants. They had to travel back in time to escape entropy and find sufficient quantities of energy to sustain them, which is why they're 10 billion light years away.
I have nothing but admiration for people who can study space and not melt down into a permanent existential crisis.
This is cool as heck, and now I’m going to go back to my computer job and try not to think about how ridiculously tiny and fragile my little life is.
Not a "distant universe" but our universe distant in time ( aka our universe in the past when it was younger ).
The title reads like astronomers found a mysterious dark object in another universe. Like a distant solar system or a distant galaxy.
Or am I misunderstanding the findings here?
Actual paper: https://www.nature.com/articles/s41550-025-02651-2
From the abstract: “This is the lowest-mass object known to us, by two orders of magnitude, to be detected at a cosmological distance by its gravitational effect. This work demonstrates the observational feasibility of using gravitational imaging to probe the million-solar-mass regime far beyond our local Universe.”
And when you are trying out a new imaging method, the selection bias for "long tail weird stuff" that shows up is pretty high.
Assuming this is repeatable, it will take a while to contextualize.
Can someone knowledgeable weigh in: is the "dark object" here believed to be a localized blob of dark matter? A dark star or black hole? Or is "dark" being used generally to mean "not bright enough to see at this distance"?
In this context, “dark object” really does mean a localized blob of dark matter, not a black hole or a dim, normal-matter object.
The research team detected it only through its gravitational lensing effect — the way it slightly distorted the light from a more distant galaxy. There’s no emission at any wavelength (optical, infrared, or radio), and its gravitational signature matches a million-solar-mass clump of invisible mass rather than a compact point source like a black hole.
They specifically interpret it as a dark matter subhalo — one of the small, dense lumps that simulations of “cold dark matter” predict should pepper the universe’s larger halos. It’s too massive to be a single star, far too diffuse to be a stellar remnant, and not luminous enough to be a faint galaxy.
So “dark” here isn’t just shorthand for “too dim to see at this distance” — it’s used in the literal physical sense: matter that doesn’t emit or absorb light at all, detectable only via gravity.
Eventually, all the dark matter clumps into rings around galaxies, but since this one is so distant, ~10B light years, so we are seeing that clump as it was that long ago before it difused into it's ring shape we can see in the galaxies around us.
Dark in the context of astrophysics means specifically that the object/matter does not interact directly with electromagnetic radiation (eg absorb an optical/microwave/radio photon). So it is probably dark matter, but probably unlikely to be a black hole because we can typically detect a black hole's effects in an indirect manner :P
From the paper, it could be the dark-matter halo of an otherwise too faint dwarf galaxy. They state that a “more definitive statement on what type of object [it] is will require deep optical/infrared observations to detect any potential EM emission”.
Definitionally, yes. It’s inert but lenses light around it.
The paper is more about the technical achievement of detecting it, IIUC. It’s not the first dark matter inference we’ve had, and doesn’t really tell us anything new about the stuff.
It challenges warm dark matter and ultralight dark matter theories because they'd be less likely to clump into something so small. Similarly MOND would have trouble explaining a completely isolated chunk of it like this.
They found a statistical anomaly that they're trying to atrribute to new physics, using some novel maths. So a tiny speck of evidence towards a new theory of matter (i know nothing about astro, just my supposition)
Or a cloaked ship?
If so it's a big one, 1M solar masses.
That’s just how warp drives happen to appear from the outside.
EXCESSION
... and its heading right for us :P
I'm an amateur but I feel confident enough to answer -- hopefully not a mistake!
They're explicitly looking for "Dark Matter", which doesn't "interact" with normal ("baryonic") matter or electromagnetic radiation (e.g. light). So it's not a black hole for sure, as those are composed of regular ol' matter.
RE:"dark star", that's really up in the air, I'd say! AFAICT the only academic reference to that term is for normal stars influenced by dark matter[1], but kinda the whole problem here is that we don't know much about what dark matter is composed of or into. Certainly it's not going to be a star in the traditional sense as it can't emit light, but I'm not aware of any reason this object can't end up being a giant sphere.
FWIW, Wikipedia says "One of the most massive stars known is Eta Carinae, with 100–200 [solar masses]", whereas this object "has a mass that is a million times greater than that of our Sun". If we're going to use metaphors, I think "dark dwarf galaxy" might be more appropriate?
[1] https://arxiv.org/pdf/1004.1258
(I’m an astrophysics undergrad.) Black holes aren’t composed of anything, they’re just defined by their charge, spin and mass equivalent.
Dust clouds have those mass ranges. It’s not a galaxy-scale mass by any measure.
This thread has a lot of CS people being confident about physics.
I was always surprised that when we talk about BHs mass, charge, and spin that we really mean U(1) (electromagnetic) gauge charge and not charges from global symmetries. (If BHs had global charge, you could at least say that this or that black hole was made out of N baryons, or whatever.)
But it's really so---according to GR, black holes don't have global charges. So even if you see a star made out of baryons collapse into a black hole, once the BH settles down into a steady state you can't say it's "really" got baryons inside: the baryon number gets destroyed.
(Of course, a different model of gravity that preserves unitarity might upset this understanding.)
And that a BH made from matter and one made from antimatter are mathematically identical, and merging them would not cause any explosion.
which doesn't "interact" with normal ("baryonic") matter
I think you mean it doesn't interact electromagnetically with either matter or radiation. It does interact with normal matter via gravity -- that's pretty much the strongest (only?) argument for its existence.
I'm not aware of any reason this object can't end up being a giant sphere
AIUI, most theories posit that solid spheres of dark matter are very unlikely because matter accretion is governed by electromagnetism in addition to gravity, and dark matter is not supposed to obey the former. Most models assume that dark matter is organized in gaseous clouds (halos); strictly speaking that's still a giant sphere, just not in the same way that Jupiter or the Sun or even the Oort Cloud is.
100-200 solar masses is not one of the largest known. There are many that are 1000s of times more massive than the sun.
This confused me too from all those solar object size comparisons I’ve seen. Turns out there are stars that are 1000s of times bigger than the sun, but they aren’t the same density.
I'm unaware of any stars in the 1000 Msun range. Wikipedia puts 291 Msun of R136a1 at the largest. After that, 195 M of R136a2 is the next. A star at 100 Msun would be in the most massive stars known.
https://en.wikipedia.org/wiki/List_of_most_massive_stars#Lis...
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Is this the first time this article author has seen “image” used like this? We image human anatomy the same way - sophisticated algorithms take the output of CT, ultrasound, MRI and build something we can interpret visually.
why would you get that impression?
my read on it.
- the quotes around image in the title
- the commenter believes image is the correct word in a more literal sense
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Yep, this still blows my mind, has a radius of 330 million light years, of, er, nothing (well 60 galaxies compared to what should be several thousand). https://en.wikipedia.org/wiki/Bo%C3%B6tes_Void
sssh, that's where we store the hammers
I think there is a shortcut being taken here.
We are surrounded by dark objects, a rock is a dark object, exoplanets are dark objects, and so are black holes. Pretty much everything but stars are dark objects. They are all dark because they don't emit light.
Here, I think they mean stuff (whatever it is) that can only be detected by gravitational lensing, and it makes sense that it has to be extremely heavy, because gravity is so weak.
I'm not a physicist but every definition of dark matter that I read says it does not interact with electromagnetic radiation hence it is invisible, and rocks are not that dark matter (wiki. NASA, etc)
So how do we know that these "dark matter objects" aren't actually just massive collections of normal matter that is dim enough and at such a far distance that it would appear (angular resolution-wise) to be invisible, but we can still detect the lensing?
> ... every definition of dark matter that I read says it does not interact with electromagnetic radiation ...
Actually, dark matter does interact with electromagnetic radiation -- it can deflect it, as in the case of gravitational lensing. But dark matter doesn't either emit nor absorb electromagnetic radiation directly.
We only know about dark matter because of its gravitational effects.
How about stellar mass black holes?
They are much lighter than 1 million solar masses and we know a few of them, with a variety of ways to detect them, including companion stars orbiting around them and gravitational waves during mergers.
Black holes fit the definition of dark matter, as they neither emit nor absorb electromagnetic radiation, not in a way that could be detected anyways. This is the "MACHO" theory of dark matter, which is not the favorite, but it is still taken seriously. Stellar mass black holes have been ruled out, I think, but it doesn't mean dark matter can't be made of black holes. In fact, primordial black holes are a rather hot theory.
yeah all those other things absorb light so they can be detected by the light they block and the infrared light the re-emit.
Dark matter seems more ghostly , like gravitational shadow of matter
If you think that's crazy, it's likely a drop in the bucket comared to the noumenonal world.
There's no reason to think that our senses encompass the vast majority of understanding everything in reality and current evidence that they, in fact, do not, via dark matter as a primary source.
I suspect our senses encompass a meaningless fraction of the noumenon.
In what way is dark matter not a phenomenon? Just because we don't know what it is doesn't make it a noumenon.
It's that it demonstrates that some sort of noumenon can likely have partial but not 'full' overlap as we understand it with a phenomenon.
To elaborate, the noumenon can have properties that are unknown to us and outside the purview of certain senses (if not all) but still have partial phenomenal effects such as gravitational effects.
Given partial overlap, we could, and likely should, surmise that overlap, if partial, can also be zero. In fact, partial overlap with certain things (such as the gravitational field) but no sensory experience is exactly what we'd predict if this were true.
The mistake is thinking I'm asserting that things are phenomenon or noumenon when that's not quite right. Mostly, the supposition is that things can exist and have either 'full' (unlikely I think), partial, or zero overlap with our sensory experience. Things that demonstrably have partial overlap suggest a wider world of things. I simply find the idea that our evolved sensory experience encompass even a sizable fraction of reality to lack epistemic humility.
This is obviously speculative.
Related: https://news.ycombinator.com/item?id=45538113
It’s nothing, mostly empty space.
Probably a small bug in the matrix
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a far away civilization probably draining energy from the emptiness of space to power some AI datacenters /s
That would be about 2.5 on the Kardashev scale, and in terms of heat, between Kim and Khloé on the Kardashian scale.
Haha, superb
Is that from the sci-fi novel "Dyson Fear" :)
That vacuum is scary. Scary overpriced.
AI to the edge meant they had to port CUDA to a JS framework.
That is literally the plot of the game Dyson Sphere Program.
https://www.youtube.com/watch?v=t_XqHWx-v_Y
I look forwards to the python tutorial for building gpt-2 with string theory
Those gen AI images of cats playing poker won't create their own energy, you know T_T
It's our descendants. They had to travel back in time to escape entropy and find sufficient quantities of energy to sustain them, which is why they're 10 billion light years away.
also, they didn't like what the future looked like
They're blaming Tylenol?! That's it, we're out of here.