This system, OJ287, is perhaps the most important system we have for understanding what happens to supermassive black holes after a galaxy merger. This is the so-called "Last Parsec Problem."
When two galaxies merge, their supermassive black holes fairly rapidly sink to the center of mass of the newly combined galaxy via dynamical friction and enter into a slow orbit around each other. Over time, the SMBHs kick out interloping stars, which removes energy from the orbit and causes the two SMBHs to come closer together. If the SMBHs were able to get within ~0.1 parsecs of each other, gravitational wave radiation could take over and cause the orbit to shrink fairly rapidly and lead to the merger of the two SMBHs.
However, the theoretical models we have generally predict that at about 1 parsec, the SMBHs have kicked out all the stars in their neighborhood, so the process stalls out. In practice we don't observe many SMBH binary systems (OJ287 being the main exception), so there must be some mechanism that causes these systems to shrink from 1 pc to 0.1 pc. But we don't know what it is. The hope is that detailed studies of the orbit of OJ287 can provide some clues as to what that missing mechanism is.
Why can't they dissipate momentum by ejecting interloping matter that is smaller than individual stars, such as regions of interstellar-medium density gas?
In Figure 3 (left panel), we show a detail of Paper II: the primary black hole is at the center, and the secondary black hole is at a PA of about 35°, at the distance of 20 μas from the primary black hole.
> The existence of two black holes in OJ287 was first suggested in 1982. Aimo Sillanpää, then a graduate student at the University of Turku, observed that the brightness of the quasar changed regularly over a 12-year cycle.
Damn, that's about the time it takes Jupiter to orbit the sun. That feels wildly close together for objects that mass 18 billion & 150 million times that of our own sun.
These black holes (according to a calculator I found online) have radii of 53 billion km and 400 million km, so I'm guessing they must be orbiting significantly further away, and significantly faster than Jupiter (which is ~800 million km away from the sun) - which makes sense, given the monstrous 18b figure. I wonder how far apart they are, but I don't really know how to easily calculate that right now.
Feature Primary Black Hole Secondary Black Hole
----------------------- ------------------------------ ------------------------------
Mass 1.8 × 10^10 M 1.5 × 10^8 M
Schwarzschild Radius 356 AU 3.0 AU
--- Circular / Average Orbital Properties ---
Orbital Period 12 years
Semi-Major Axis 13,800 AU (~0.22 ly)
Orbital Speed (avg) 282 km/s (0.094% c) 33,900 km/s (11.3% c)
--- Elliptical Orbit (e ≈ 0.65) ---
Pericenter Distance 4,830 AU (same)
Orbital Speed (peri) 613 km/s (0.20% c) 73,600 km/s (24.5% c)
Apocenter Distance 22,800 AU (same)
Orbital Speed (apo) 130 km/s (0.043% c) 15,600 km/s (5.2% c)
So the "smaller" SMBH is punching through the larger one's disk at a significant fraction of c twice every 12 years. But it's losing energy to gravitational waves so quickly that they'll probably merge in around 10,000 years [1]
Such a system would make easy[1] for any civilization living nearby to launch spaceships at a large fraction of the speed of light. But the tricky part would be braking at the destination, unless your destination is a similar and suitably aligned system.
> the "smaller" SMBH is punching through the larger one's disk at a significant fraction of c twice every 12 years. But it's losing energy to gravitational waves so quickly
Bro should get in shape before they start to clap cheeks
In Newtonian gravity, the relation between the orbital period T and the semimajor axis a of the orbital ellipse is a^3 / T^2 = GM / 4π^2, where M is the reduced mass of the system (in this case, with 99% of the mass being in one of the two black holes, it's simply the mass of the heavier one).
Plugging 12 years and 18e9 solar masses gives about 2e12 kilometers, or roughly a fifth of a lightyear. This also means the smaller black hole is zipping around the bigger one at around 6% of the speed of light, which is low enough that the Newtonian approximation is probably reasonable accurate (at least to give a rough idea of how large the distances must be).
Kepler’s laws should still provide a pretty good estimate, at least until black holes get much closer. I did a quick back of the envelope calculation, and looks like they’ll be roughly 14k astronomical units, or 0.22 light years apart.
You made me wonder about the orbital speed of a planet circling one of these supermassive black holes, and how fast it would be... and then I realized, of course, the orbital speed would approach the speed of light at the event horizon.
There's a SF story waiting to be written about a planet just over that radius, traveling at something like 0.99c. Years would takes seconds, and seem even faster since they'd be significantly time-dilated. Of course, they'd quickly spiral in.
How much time dilation do you get at those masses though?
I’m having more trouble visualizing how accretion disks would work for a binary black hole. Because the light is coming from the disks, not the black holes. So those are what are actually pulsing/girating.
One more flare happened since then, in 2022, but because of instrumental limitations, it was caught only at a prestage (M. J. Valtonen et al. 2023; M. J. Valtonen 2024). At the same time, more flares were discovered in historical photographic plate studies so that only eight of the expected 26 flares remain unconfirmed (R. Hudec et al. 2013). All the unconfirmed ones are due to lack of known photographs at the expected epochs.
I understand that patterns and confirmations often come from data captured years ago and reanalyzed. That’s how some comets are discovered.
What I don’t get is how you can say we are publishing the first picture and then post a picture that was published three years ago.
It looks like HN has now changed the title from the “all editors should be fired” exhibit list to something more reasonable, but the linked article is still titled, “Scientists capture first image of two black holes in orbit.”
which editors should be fired? You mean the scientific journal editors?
As to the image, "The image shows two bright points, each representing a jet of high-energy particles emitted by one of the black holes.
The black holes themselves remain invisible, but the image provides clear visual evidence of their position, motion, and dual existence. "
My best guess is that it took a few years to interpret the data. Frankly, I don't get the math. The numbers are so big! But I feel pretty small when considering this... and, of course, soon we'll hear of even more of these systems.
Do you think that gravitational lens effects will be studied when "the stars are aligned" for other studies?
It’s died down lately but there has been a lot of spleen venting here about how shit article titles are compared to their contents. Often implying the exact opposite of the contents. The usual explanation is that editors pick the titles. And then there is a lot of uncharitable speculation about what exactly editors are good for given they are so overwhelmingly awful at titles. Which I am all too happy to participate in.
What’s interesting is the policy here used to be no editorializing on titles. But the title of this thread has been changed to something more like the paper and less like the article describing it. Seemingly in violation of that old policy. I hope that means I’ve missed a shift in policy happening.
This system, OJ287, is perhaps the most important system we have for understanding what happens to supermassive black holes after a galaxy merger. This is the so-called "Last Parsec Problem."
When two galaxies merge, their supermassive black holes fairly rapidly sink to the center of mass of the newly combined galaxy via dynamical friction and enter into a slow orbit around each other. Over time, the SMBHs kick out interloping stars, which removes energy from the orbit and causes the two SMBHs to come closer together. If the SMBHs were able to get within ~0.1 parsecs of each other, gravitational wave radiation could take over and cause the orbit to shrink fairly rapidly and lead to the merger of the two SMBHs.
However, the theoretical models we have generally predict that at about 1 parsec, the SMBHs have kicked out all the stars in their neighborhood, so the process stalls out. In practice we don't observe many SMBH binary systems (OJ287 being the main exception), so there must be some mechanism that causes these systems to shrink from 1 pc to 0.1 pc. But we don't know what it is. The hope is that detailed studies of the orbit of OJ287 can provide some clues as to what that missing mechanism is.
Why can't they dissipate momentum by ejecting interloping matter that is smaller than individual stars, such as regions of interstellar-medium density gas?
They do, but there's just not that much mass compared to stars.
The diagram in the article shows them 0.02 apart, with no units that I can see. Parsecs? Light years? Arc-seconds? Does anybody know?
Other commenters have proposed 0.22 light years, but if that's it, it's off from the diagram by a factor of 10...
In Figure 3 (left panel), we show a detail of Paper II: the primary black hole is at the center, and the secondary black hole is at a PA of about 35°, at the distance of 20 μas from the primary black hole.
https://iopscience.iop.org/article/10.3847/1538-4357/ae057e
Aha! Micro arc seconds!
Thank you.
> The existence of two black holes in OJ287 was first suggested in 1982. Aimo Sillanpää, then a graduate student at the University of Turku, observed that the brightness of the quasar changed regularly over a 12-year cycle.
Damn, that's about the time it takes Jupiter to orbit the sun. That feels wildly close together for objects that mass 18 billion & 150 million times that of our own sun.
These black holes (according to a calculator I found online) have radii of 53 billion km and 400 million km, so I'm guessing they must be orbiting significantly further away, and significantly faster than Jupiter (which is ~800 million km away from the sun) - which makes sense, given the monstrous 18b figure. I wonder how far apart they are, but I don't really know how to easily calculate that right now.
[1] https://archive.is/Ccy5M
Such a system would make easy[1] for any civilization living nearby to launch spaceships at a large fraction of the speed of light. But the tricky part would be braking at the destination, unless your destination is a similar and suitably aligned system.
[1] https://www.centauri-dreams.org/2023/06/08/freeman-dysons-gr...
Orbiting at c/6 - WOW!
The relativistiv effects must be wild there!
> the "smaller" SMBH is punching through the larger one's disk at a significant fraction of c twice every 12 years. But it's losing energy to gravitational waves so quickly
Bro should get in shape before they start to clap cheeks
In Newtonian gravity, the relation between the orbital period T and the semimajor axis a of the orbital ellipse is a^3 / T^2 = GM / 4π^2, where M is the reduced mass of the system (in this case, with 99% of the mass being in one of the two black holes, it's simply the mass of the heavier one).
Plugging 12 years and 18e9 solar masses gives about 2e12 kilometers, or roughly a fifth of a lightyear. This also means the smaller black hole is zipping around the bigger one at around 6% of the speed of light, which is low enough that the Newtonian approximation is probably reasonable accurate (at least to give a rough idea of how large the distances must be).
Kepler’s laws should still provide a pretty good estimate, at least until black holes get much closer. I did a quick back of the envelope calculation, and looks like they’ll be roughly 14k astronomical units, or 0.22 light years apart.
You made me wonder about the orbital speed of a planet circling one of these supermassive black holes, and how fast it would be... and then I realized, of course, the orbital speed would approach the speed of light at the event horizon.
There's a SF story waiting to be written about a planet just over that radius, traveling at something like 0.99c. Years would takes seconds, and seem even faster since they'd be significantly time-dilated. Of course, they'd quickly spiral in.
How much time dilation do you get at those masses though?
I’m having more trouble visualizing how accretion disks would work for a binary black hole. Because the light is coming from the disks, not the black holes. So those are what are actually pulsing/girating.
Unless I screwed up the math, they would be quarter of a light year apart. Plenty of space for each black hole to form its own accretion disk.
Oh that chart is really awful then. It’s showing an accretion disk that’s half a light year in diameter at least.
Yeah, good point on that, too. I bet someone's written a simulator that I could run locally, but I've got a busy day ahead of me :(
I thought that in this case, the light that they detected was coming from the jets coming from the poles, not the disk itself directly.
Since black holes are black holes, the jets are generated by the disk.
Why “just released” if the paper the image came from is dated 2022?
maybe this:
One more flare happened since then, in 2022, but because of instrumental limitations, it was caught only at a prestage (M. J. Valtonen et al. 2023; M. J. Valtonen 2024). At the same time, more flares were discovered in historical photographic plate studies so that only eight of the expected 26 flares remain unconfirmed (R. Hudec et al. 2013). All the unconfirmed ones are due to lack of known photographs at the expected epochs.
https://iopscience.iop.org/article/10.3847/1538-4357/ae057e
I understand that patterns and confirmations often come from data captured years ago and reanalyzed. That’s how some comets are discovered.
What I don’t get is how you can say we are publishing the first picture and then post a picture that was published three years ago.
It looks like HN has now changed the title from the “all editors should be fired” exhibit list to something more reasonable, but the linked article is still titled, “Scientists capture first image of two black holes in orbit.”
which editors should be fired? You mean the scientific journal editors?
As to the image, "The image shows two bright points, each representing a jet of high-energy particles emitted by one of the black holes. The black holes themselves remain invisible, but the image provides clear visual evidence of their position, motion, and dual existence. "
My best guess is that it took a few years to interpret the data. Frankly, I don't get the math. The numbers are so big! But I feel pretty small when considering this... and, of course, soon we'll hear of even more of these systems.
Do you think that gravitational lens effects will be studied when "the stars are aligned" for other studies?
> You mean the scientific journal editors?
It’s died down lately but there has been a lot of spleen venting here about how shit article titles are compared to their contents. Often implying the exact opposite of the contents. The usual explanation is that editors pick the titles. And then there is a lot of uncharitable speculation about what exactly editors are good for given they are so overwhelmingly awful at titles. Which I am all too happy to participate in.
What’s interesting is the policy here used to be no editorializing on titles. But the title of this thread has been changed to something more like the paper and less like the article describing it. Seemingly in violation of that old policy. I hope that means I’ve missed a shift in policy happening.
where is the image ?
*Muse starts playing somewhere in the cosmos