A study shows the unexpected effect of black holes beyond their own galaxies


Research News


At the heart of almost every sufficiently massive galaxy there is a black hole whose gravitational field, although very intense, affects only a small region around the centre of the galaxy. Even though these objects are thousands of millions of times smaller than their host galaxies our current view is that the Universe can be understood only if the evolution of galaxies is regulated by the activity of these black holes, because without them the observed properties of the galaxies cannot be explained.

Theoretical predictions suggest that as these black holes grow they generate sufficient energy to heat up and drive out the gas within galaxies to great distances. Observing and describing the mechanism by which this energy interacts with galaxies and modifies their evolution is therefore a basic question in present day Astrophysics.

With this aim in mind, a study led by Ignacio Martín Navarro, a researcher at the Instituto de Astrofísica de Canarias (IAC), has gone a step further and has tried to see whether the matter and energy emitted from around these black holes can alter the evolution, not only of the host galaxy, but also of the satellite galaxies around it, at even greater distances. To do this, the team has used the Sloan Digital Sky Survey, which allowed them to analyse the properties of the galaxies in thousands of groups and clusters. The conclusions of this study, started during Ignacio’s stay at the Max Planck Institute for Astrophysics, are published today in Nature magazine.

“Surprisingly we found that the satellite galaxies formed more or fewer stars depending on their orientation with respect to the central galaxy”, explains Annalisa Pillepich, researcher at the Max Planck Institute for Astronomy (MPIA, Germany) and co-author of the article. To try to explain this geometrical effect on the properties of the satellite galaxies the researchers used a cosmological simulation of the Universe called Illustris-TNG whose code contains a specific way of handling the interaction between central black holes and their host galaxies. “Just as with the observations, the Illustris-TNG simulation shows a clear modulation of the star formation rate in satellite galaxies depending on their position with respect to the central galaxy”, she adds.

This result is doubly important because it gives observational support for the idea that central black holes play an important role in regulating the evolution of galaxies, which is a basic feature of our current understanding of the Universe. Nevertheless, this hypothesis is continually questioned, given the difficulty of measuring the possible effect of the black holes in real galaxies, rather than considering only theoretical implications.

These results suggest, then, that there is a particular coupling between the black holes and their galaxies, by which they can expel matter to great distances from the galactic centres, and can even affect the evolution of other nearby galaxies. “So not only can we observe the effects of central black holes on the evolution of galaxies, but our analysis opens the way to understand the details of the interaction”, explains Ignacio Martín Navarro, who is the first author of the article.

“This work has been possible due to collaboration between two communities: the observers and the theorists which, in the field of extragalactic Astrophysics, are finding that cosmological simulations are a useful tool to understand how the Universe behaves”, he concludes.


Article: Ignacio Martín Navarro, Annalisa Pillepich, et al. “Anisotropic satellite quenching modulated by black hole activity”. Nature, June 10, 2021. DOI: 10.1038/s41586-021-03545-9

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M Courtney
June 10, 2021 12:31 am

This work has been possible due to collaboration between two communities: the observers and the theorists

Sounds like proper science to me.

John Tillman
Reply to  M Courtney
June 10, 2021 5:46 am

Here’s a proper use of models and observation to determine whether the excess of gamma rays in the galactic center comes from pulsars or dark matter:


June 10, 2021 1:25 am

Interestingly the observations tend to follow the analysis and modelling unlike climate science. Real data, real science.

Reply to  Quilter52
June 10, 2021 4:00 am

except the modeling is based on even worse math than in climate…. half the equations assholephysicists use to support their fantasy violate the rules of the source equations and the laws of physics.

Reply to  Prjindigo
June 11, 2021 2:49 pm

Nonsense. Show us one.

June 10, 2021 1:57 am

Paper over at [2106.04587] Anisotropic satellite galaxy quenching modulated by supermassive black hole activity (arxiv.org)
‘The evolution of satellite galaxies is shaped by their constant interaction with the circum galactic medium surrounding central galaxies, which in turn may be affected by gas and energy ejected from the central supermassive black hole. However, the nature of this coupling between black holes and galaxies is highly debated and observational evidence remains scarce. Here we report an analysis of archival data on 124,163 satellite galaxies in the potential wells of 29,631 dark matter halos with masses between 1012 and 1014 solar masses. We find that quiescent satellites are relatively less frequent along the minor axis of their central galaxies. This observation might appear counterintuitive as black hole activity is expected to eject mass and energy preferentially in the direction of the minor axis of the host galaxy. However, we show that the observed signal results precisely from the ejective nature of black hole feedback in massive halos, as active galactic nuclei-powered outflows clear out the circumgalactic medium, reducing the ram pressure and thus preserving star formation. This interpretation is supported by the IllustrisTNG suite of cosmological numerical simulations, where a similar modulation is observed even though the sub-grid implementation of black hole feedback is effectively isotropic. Our results provide compelling observational evidence for the role of black holes in regulating galaxy evolution over spatial scales differing by several orders of magnitude.’

This involves dark matter feedback when ‘observational evidence remains scarce’ !

I wonder have they some astro-climateers onboard?

Reply to  bonbon
June 10, 2021 6:44 am

Whereas the astros paint gray holes with dark matter, the climateers smooth chaos with brown matter. Both infer plausible systems and processes from assumed/asserted signals of variable or unverifiable fidelity outside of a limited frame of reference. That said, it should be interesting to one day learn if there is a consensus between theory and reality in the scientific domain.

June 10, 2021 2:39 am

Post says: ““Surprisingly we found that the satellite galaxies formed more or fewer stars depending on their …”

I did not know that we knew the correct number of stars that satellite galaxies were suppose to form so that we could judge whether “more or fewer” were in fact formed.

James Donald Bailey
Reply to  mkelly
June 10, 2021 8:58 am

More or fewer can be judged without reference to some ideal. E.g. More new stars created in this galaxy than created in that galaxy. Or more stars created in this galaxy per the number of existing stars in said galaxy compared to the same ratio of that galaxy.

It is more bothersome that the simulation is different than what they think is happening yet it produces the same results. Simulation uses isotropic mass source, same in all directions, produces non-isotropic results, agreeing with observations that are believed to be due to non-isotropic mass source.

The most a simulation can achieve is proof that you are wrong. “I made an accurate simulation of my theory and the simulation failed to produce the results the theory predicted.” Really hard to prove that the simulation is accurate to reality, as opposed to accurate to a theory. So when the simulation shows the same results, you don’t have proof that you are right, just that you haven’t proven yourself wrong.

This simulation can’t prove their theory wrong, because they didn’t correctly apply their theory in the simulation. Except, it comes close to disproving it by achieving the desired results by different means. It also contains a hint that could possibly lead to better understanding. Some mechanism in their simulation did produce the desired results.

But it is also possible that bad theories can produce desired results. Physics has a history of accepting and then overturning bad theories.

And I switched from a neutral producing the results of the theory to a proactive producing the desired results. Producing the results seen in observations fits in between. That is of course the desired result of any theory, but the scientific process is supposed to not let that desire affect the results or the interpretation of the results. What I am bothered about hints at the latter.

Joseph Zorzin
June 10, 2021 2:59 am

black holes matter

Reply to  Joseph Zorzin
June 10, 2021 4:00 am

they cease to exist when created, actually something about time and mass

Reply to  Joseph Zorzin
June 10, 2021 6:48 am

black whores matter h/t NAACP

June 10, 2021 3:58 am

except they just finally discovered that there aren’t any black holes at the centers of galaxies… something about the galaxies being inductive motors at their cores and flinging everything out along the axis

Reply to  Prjindigo
June 11, 2021 2:50 pm

perhaps you’d like to cite a reference?

Toby Nixon
June 10, 2021 4:38 am

And why exactly is taxpayer money spent on this stuff?

Tom in Florida
Reply to  Toby Nixon
June 10, 2021 8:44 am

So said those who turned down Christopher Columbus.

Joseph Zorzin
Reply to  Tom in Florida
June 10, 2021 12:59 pm

some once thought the Earth was flat- but ironically, astronomers now think the universe is flat or so flat on such a large scale, any curvature can’t yet be measured

Reply to  Joseph Zorzin
June 11, 2021 2:51 pm

I hope this was a joke. Flat in 3-D is not the same as flat in 4-D.

Reply to  Tom in Florida
June 11, 2021 5:54 pm

Columbus wanted to get to Asia by sailing west from Europe. He had trouble getting funded because most of the people he approached knew that such a trip would be much too far for the amount of food and fresh water he could carry with him. Only the then-unknown presence of the Americas saved him and his crews from a lonely and miserable death when he finally did scare up funding.

Reply to  Steve
June 18, 2021 3:53 am

Not quite. Columbus had a map with data from Venice’s Marco Polo. It showed Cipango where Mexico actually is. In other words Polo had exaggerated scale of his adventures. Columbus, as his son wrote, always believed he had reached Cipango. In other words he knew he had enough food. What was really going on is that trip west was a mortal threat to the Venice chokehold on Asian trade. One ever tried to scare sailors into murdering Columbus and turning back when a bird saved the day.
There is some evidence that Columbus, after waiting 7 years for funding, got the green light after Granada was seized during the ongoing Moor expulsion. That after all is a grain store, and there were petroglyphs of corn cobs found there from earlier. Columbus’ Basque captains regularly fished off Newfoundland, even selling salted fish in Rotterdam.

Reply to  Toby Nixon
June 10, 2021 1:12 pm


“The Effect of Climate Change on Star Formation Rates in Satellite Galaxies”

June 10, 2021 4:42 am

black hole whose gravitational field, although very intense, affects only a small region around the centre of the galaxy”


Galactic collisions end up with the celestial bodies of two galaxies rotating around a common barycentric center of rotation. Often with the two galactic blackholes are locked into orbits around the barycentric center until one black hole feeds/collides on the other.
As we live, the Milky Way Galaxy is on collision course with the Andromeda Galaxy and is believed to have previously collided with other galaxies.
Post collision with Andromeda, the combined ‘Milky Way’-Andromeda galactic mass will collide with smaller galaxies.

Triangulum galaxy, M33, will join in the collision and perhaps later merge with the M31/Milky Way pair. There is a small chance that M33 will hit the Milky Way first.”

June 10, 2021 6:06 am

…there is a particular coupling between the black holes and their galaxies…

It’s the battle of the bulge.

Last edited 1 year ago by strativarius
June 10, 2021 6:56 am

So how long before “studies” come out blaming people of modern western civilizations of life style choices that are harming black holes?

Reply to  AWG
June 10, 2021 7:44 am

So how long before “studies” come out blaming people white men of modern western civilizations of life style choices that are harming black holes?

There, fixed.

paul courtney
Reply to  AWG
June 10, 2021 1:01 pm

AWG: It’s here, it’s called AGW (Anthropogenic Galactic Warming). To stop it, we must stop burning coal and oil.
The left has problems explaining things, but the answer is always the same, so that helps.

June 10, 2021 7:36 am

Black hole subject almost always brings forth black hole trolls.

Reply to  Anti_griff
June 10, 2021 2:42 pm

Isn’t it the truth!

June 10, 2021 9:29 am

How the universe works. Still working on it.

June 10, 2021 11:59 am

Not long ago I was listening to an up to date interview with Roger Penrose, and he himself said that (to paraphrase) ‘there too many things we don’t know and there too few facts we do know about black holes’. In view of such assessment as it is usually said ‘more research is required’. It is good to hear about a new hypothesis or conjecture but I remain sceptic on many of the pronouncements regarding black holes, and even more so on the matters regarding Big bang ( Roger Penrose also talked about it too), dark matter and dark energy.

Reply to  Vuk
June 10, 2021 12:56 pm

There are too many things on this planet we do not understand, let alone depths of distant cosmos. Egyptian or Maya Pyramids, Stone henge etc all fascinating and make sense but here is something built by humans that hardly makes any sense whatsoever.
These Google Earth coordinates 43°42’10″N , 15°43’40E do not show human fingerprint, but something even more complex.
It is a small island just 1/20th of a square mile (14 hectares) in the Adriatic sea, it has an incomprehensible labyrinth of approximately 14 miles long of 6+ foot high dry stone walls all hand built.
If intrigued enough there is drone video overflight here
It is assumed these were olive growing plots of individual families from the nearby mainland.

J Mac
June 10, 2021 11:59 am

Curiouser and curiouser…….

June 10, 2021 12:02 pm

My my my, I just love the learned pronouncements of today’s astrophysicists, who, seeing through a glass so dark as to be almost entire opaque, are so certain that their theoretical (merely hypothesized) ideas are facts that can be checked against data so speculative that it, if looked at pragmatically, renders any and all judgements nonsensical.

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