Tag: Active Galactic Nuclei

Astronomy News for February 2025: The latest results from the James Webb Space Telescope. 

It seems as though every time that astronomers build a new instrument, one that’s bigger, or more precise or one that looks at the sky above in a different way the discoveries made by that instrument challenge if not actually break existing theories about the Universe. It all started when Galileo first pointed his primitive telescope skyward and saw the moons of Jupiter, spots on the Sun, the phases of Venus and saw that the Milky Way was actually composed of thousands, millions of stars. As optical telescopes got bigger and bigger they saw more things like nebula and star clusters. Then, when astronomers added spectrographs to their telescopes they were able to discover what elements the stars were made of.

Two Telescope made by Galileo. With these instruments Galileo began the revolution in our understanding of the Universe that continues to this day! (Credit: Britannica)

In the 20th century radio telescopes discovered objects like pulsars and quasars while X-ray telescopes discovered black holes. With each new technological advance in the astronomer’s instruments came a better understanding of the Universe even if that meant tossing aside some older, well established ideas.

Today we build large arrays of radio telescopes in order to get an even clearer view of what lies out there! (Credit: PrimalLuceLab)

Observations by the James Webb Space Telescope (JWST) began to astound astronomers within weeks of its beginning operation in 2022. You see, the JWST was designed primarily to study the early Universe, around a billion years after the Big Bang. If you’re wondering how a telescope can see into the past remember that since the speed of light is a finite 300,000 kilometers per second all you have to do is look at something billions of light years away and you’ll be seeing it as it was billions of years ago.

In operation less than three years the James Webb Space Telescope (JWST) has already shaken up many of our theories about the early Universe. (Credit: European Space Agency)

But you better have a big telescope, and you better put that telescope in space so it can just stare at the object you’re observing for hours or days or longer to gather enough light. Oh, and since the entire Universe is expanding the Doppler effect is going to cause that light from billions of years ago to be shifted to longer wavelengths, you’ll have to build your telescope to see in the infrared. That means you’ll have to get it away from any heat sources like the Sun and Earth, which is why the JWST was placed at the Lagrangian (L1) point in the Earth’s shadow but a million kilometers from our planet.

The five Lagrangian points are the only exact solutions to the ‘Three Body Problem’ in celestial mechanics. Only L4 and L5 are really stable but the JWST is located at Earth’s L1 point where it only requires occasional adjustments to its orbit. (Credit: Australian Space Academy)

So as I said, JWST was primarily designed to study the Universe only a billion or so years after the big bang and those were some of the first images it took. Astronomers were interested in that period because they theorized that was the time that the first stars began to shine, that the first galaxies began to form. (See my post of 6 July 2024.)

Just a few years ago this was our best idea of the evolution of the Universe. After the big bang cooled off there was a period called the dark ages that lasted until about 400 million years after the big bang when the first stars began to shine. The first galaxies formed not long after that. The JWST has already forced us to make some changes to that timetable. (Credit: NASA Science)

One question that it was hoped that the JWST could answer dealt with the supermassive black holes that astronomers are now convinced lie at the heart of every galaxy, at least every big one. Simply put, the question was, which came first? Did galaxies form supermassive black holes in their centers, or do supermassive black holes form galaxies around them? Obviously any theory of how galaxies form needs to know that.

The first ever image of a supermassive black hole in the center of the galaxy M87. What you actually see here is not the hole itself but the ring of material that is falling into the hole and heating up so that it shines! (Credit: Wikipedia)

What the JWST did in fact see when it made its first observations were a large number of what astronomers named ‘Little Red Dots’, that is small but rather bright galaxies with a reddish glow to them. By their brightness the red dots appeared to contain millions of bright stars and some of them were found to have existed less than half a billion years after the big bang, a time so early that according to most theories of galaxy formation no such well developed galaxies should exist. That was why there were so many news articles about JWST having ‘Broken Cosmology’.

Some of the ‘Little Red Dots’ observed by the JWST. These ‘proto-galaxies’ appear to have formed much earlier than cosmologists expected. (Credit: Space.com)

That was about two years ago and since then the JWST has both discovered a lot more ‘Little Red Dots’ and made much more detailed and precise measurements of some of them. Now a team of astronomers headed by Dale Kocevski of Colby College has announced results of their survey of the red dots at a conference of the American Astronomical Society that was held in Maryland the second week in January.

The recent 245th meeting of the American Astronomical Society must have been a fun party!!!! (Credit: Threads)

What the astronomers found was that the better observations of the red dots all showed light signatures indicating that much of their light came from hot gasses spiraling into a growing black hole. So the reason the red dots were so bright wasn’t because they had millions of stars but because they had the beginnings of a Quasar, a feeding black hole in their center. The JWST observations don’t break current theories of cosmology but those theories are certainly going to have to be modified.

Six Quasars as seen in an optical telescope. Today we know that these objects are galaxies with a feeding supermassive black hole at their center that is giving off so much light that it is outshining the entire galaxy around it. (Credit: Britannica)

The case isn’t closed yet however, because about a billion years after the big bang all of the red dots seem to disappear. Dr. Kocevski and the other astronomers in the team think that, as the black hole forms a galaxy around it will start to take on the appearance of a more ‘normal’ active galactic nuclei (AGN).

Quasars are often also referred to as ‘Active Galactic Nuclei’ (AGN). The question for astronomers is how did the ‘Little Red Dots’ evolve into AGN? (Credit: Medium)

So it seems that the JWST has given us the answer to our question about which came first: galaxies or the supermassive black holes inside them. The ‘Little Red Dots’ are black holes that serve as the seeds of galaxy formation. But like every other scientific answer this one breeds another question; where do the black holes that form the ‘Little Red Dots’ come from?

The Active Galactic Nuclei (AGN) at the heart of Galaxy 1ES 1927+654 increased in brightness by over a hundred times for several months back in 2017. What can that tell us about the Supermassive Black Hole that powers the AGN?

The supermassive black hole at the center of our Milky Way galaxy is quiet right now, that is, it is not actively feeding on nearby gas and dust, to say nothing of planets and stars. All of the supermassive black holes in the galaxies close to ours are like that, quiet.

Astronomers are convinced that every large galaxy, this is Andromeda, has a supermassive black hole at their center. So in the early Universe did supermassive black holes form galaxies around them or do galaxies form supermassive black holes inside them? That’s one of the questions the new James Webb Space Telescope was designed to help answer. (Credit: Space.com)

As we look at galaxies further away, the picture changes. The supermassive black holes in distant galaxies are usually surrounded by an ‘accretion disk’ of matter that is slowly falling into the black hole. The energy released by all of that matter falling into the black hole causes the accretion disk to shine as brightly as thousands or even millions of stars. These radiating objects are technically known as ‘Active Galactic Nuclei’ or AGN and are among the brightest objects in the Universe.

Here’s a galaxy with a very active galactic nuclei. The energy released by matter falling into the supermassive black hole at this galaxy’s center is outshining the billions of ordinary stars in the galaxy itself. (Credit: Think Big)

 Now remember in astronomy the further away you look from Earth the further back in time the object you’re seeing is. The brightest star Sirius is about ten light years away so the light you see it by took ten years to reach your eye so what you are seeing is Sirius as it looked ten years ago. The same is true of the pole star Polaris, which is about 500 light years away. When you look at Polaris in the night sky you are seeing it as it was 500 years ago.

Every Boy Scout knows that to find Polaris, the pole star you use the front two stars of the Big Dipper. Now Polaris is about 500 light years away so the light we see at night left the star 500 years ago. Therefore today we see Polaris as it was 500 years ago. (Credit: BBC Science Focus Magazine)

So when astronomers see that the supermassive black holes in nearby galaxies are quiet, that is not feeding, while the supermassive black holes in more distant galaxies are more active it’s telling them that over time those black holes consumed all of the matter close to them and only stopped feeding because there’s nothing left nearby for them to eat. In this way astronomers have been able to model the life cycle of supermassive black holes going from actively feeding to quiet as they deplete the matter around them.

The various parts of an AGN. The Supermassive Black Hole pulling matter into itself powers the whole AGN. (Credit: NASA)

This transition from active to quiet takes a very long time, upwards of a billion years or more making supermassive black holes rather stable objects. It came as something of a shock therefore when in late 2017 the AGN at the center of galaxy 1ES 1927+654 suddenly increased in brightness by a factor of nearly 100 in the visible part of the spectrum. As stated by Nicolas Scepi, a postdoctoral researcher at the University of Colorado and the National Institute of Standards and Technology (NIST) and a member of the team studying 1ES 1927+654, “Normally we would expect black holes to evolve over millions of years.” So unusual was the change in that a large team of astronomers working across the electromagnetic spectrum from radio waves to X-rays was quickly assembled to investigate 1ES 1927+654 at every wavelength.

Image of the Galaxy 1ES 1927+654 (Credit: Poandpo.com

What the researchers found was that, even as the brightness of 1ES 1927+654 increased by a factor of 100 in both the visible and ultra-violet (UV) portions of the spectrum it decreased by a factor of 1000 in the X-ray spectrum. The observation that the intensity of UV and X-rays went in opposite directions was in itself a surprise, as the strength of X-rays and UV generally go hand in hand.

Some of the data taken of galaxy 1ES 1927+654 during the time when its AGN appears to have flipped its magnetic field. (Credit:

But that unexpected decrease in X-ray output was the clue that Doctor Scepi and his colleagues at the University of Colorado needed to solve the puzzle of 1ES 1927+654. In a paper published in the Monthly Notices of the Royal Astronomical Society the astro-physicists argue that the magnetic field generated by the charged particles making up the accretion disk around the supermassive black hole flipped its north and south poles causing the change in the AGNs brightness.

Now scientists already know of two astronomical bodies whose magnetic field flips their poles on occasion. The Sun’s magnetic field flips as a part of its eleven year sunspot cycle. The Earth’s magnetic field also cycles back and forth although the cycle is much longer, the best estimates being about every 200,000 years and we are now overdue for such a flip. See my post of February 8th, 2017 concerning evidence that Earth’s field is currently starting just such a flip. Whether or not other stars and planets, Jupiter perhaps, also flip their magnetic fields is the subject of active research among astronomers and astro-physicists.

Earth’s magnetic field is very messy right now with a big piece of the north pole in the south while bits of the south are poking out of the north. Are these signs that the field is getting ready to flip? (Credit: Extreme Tech)

For the accretion disk of an AGN to flip its magnetic field was unexpected however. The theory put forth by Scepi and his colleagues suggests that new matter being pulled into the accretion disk possesses the opposite orientation of the existing magnetic field, weakening and then flipping it. The team’s calculations showed that the result of the flip would be an increase in the visible and UV spectra at the expense of X-rays, exactly what was observed in 1ES 1927+654.

The light our eyes can see is only a small portion of the Electromagnetic Spectrum. When galaxy 1ES 1929+654 grew in brightness in the visible and ultraviolet parts it also lost intensity in the X-ray portion so the total energy output remained pretty constant! (Credit: NOAA)

If one AGN can flip its magnetic field can’t others. The behaviour exhibited by 1ES 1927+654 may actually be fairly common, astronomers simply haven’t been looking for it. But they certainly will be now that they know what to look for. I think before long astronomers will have found few more oddly behaving AGN and they will provide more data to help the theorists refine their models of their magnetic fields.

Imaged by the Event Horizon Telescope project, the same team that obtained the first picture of a black hole, here is the Supermassive Black Hole at the center of our own Milky Way galaxy known as Sagittarius A. (Credit: CNN)

Even as I was writing this post the Event Horizon Telescope, the same group who gave us the first picture of a black hole back in 2019, see my post of 17th of April 2019, have accomplished the same feat with the supermassive black hole at the center of our Milky Way galaxy. The black hole, known officially as Sagittarius A, is quiet now, its accretion disk is very small. Nevertheless the information gathered from the new image will tell us a great deal as we continue to try to understand the mysteries of Supermassive Black Holes.