JWST Reveals the Sombrero Galaxy's Massive Hidden Secret

[00:00:00]Hello everyone, this is Anton, and today we're going to discuss one of the most iconic galaxies out there, Messier 104 or the Sombrero Galaxy, named after the iconic Mexican hat. And well, for decades this galaxy has been a favorite for both amateur astronomers and professionals, mostly because it was relatively easy to find and because of its iconic shape. Specifically, this very bright bulbous core and relatively thick dark dust lane that basically that makes it resemble a sombrero. But the thing is, when it comes to various things in space, looks can be very deceiving. Because as recent studies based on the James Webb Space Telescope observations, along with the observations from the Dark Energy Camera revealed, this galaxy has a bit of a split personality. And it also seems to be much more violent than we once thought. And so, let's talk about some of the recent discoveries about this galaxy, but first a little bit of history. Because as you can imagine, this was discovered a long time ago, 1781.

[00:01:04]And it was actually originally found by Pierre Méchain, a slightly [clears throat] less known astronomer, who was a colleague of Charles Messier, and who basically told him about it.

[00:01:15]Because originally, this was not part of the famous Charles Messier's catalog that we now refer to as the Messier catalog. But Messier did write about this in his personal copy, and so it was not officially added to the catalog until 1921. But because this was such an easily visible object, it was also independently discovered by William Herschel, who also described this galaxy in 1784 and was actually the first to notice the bizarre dark lane. He actually called it a dark stratum, which today we know is essentially a massive amount of dust or basically a dust lane that forms a kind of a ring around this galaxy, encircling the core. And so, because of this ring and because of additional observations, for a very long time astronomers classified this galaxy as a standard spiral galaxy, not so different from the Milky Way, except that in this case visible from the edge.

[00:02:09]But, our understanding of this object changed dramatically once additional telescopes, especially infrared telescopes, started to take a look as well. And specifically telescopes like the Spitzer Space Telescope that allowed astronomers to discover something in entirely different and invisible to some of these earlier astronomers. And the first discovery here was the galactic halo, the sphere of stars surrounding this galaxy that seems to be much larger and much more massive than expected from a typical spiral galaxy. And that's because usually these large halos are kind of a definition and a signature for elliptical galaxies, such as the famous M87. These are normally galaxies that are much more rounded and contain a huge amount of stars, usually very ancient stars, moving in a somewhat random motion. And we believe they are very likely the result of multiple collisions where the entire spiral structure of the galaxy gets destroyed with time. But, in this case, it looks like the Sombrero Galaxy is sort of both, two galaxies in one, a flat dusty disk that's embedded inside a massive old elliptical spheroid. So, it's essentially a hybrid.

[00:03:23]And for a very long time, nobody knew exactly how it got that way, which of course made this galaxy suddenly way more interesting. How exactly did this form? But, the mysteries here did not end because even its center seems to be somewhat strange. And that's because the nucleus of this galaxy, or the center of the galaxy, is classified as a LINER, low ionization nuclear emission line region. Or just to rephrase this, the nucleus seems to ionize a lot of gas inside of it because something extremely powerful is happening right in the center. And this suggests that there is a very powerful active galactic nucleus or a massive black hole. But because the gas is only weakly ionized, it's not a black hole that's super loud. And so in the '90s, using the Hubble Space Telescope, researchers definitely confirmed the evidence for this supermassive black hole with the initial estimate to be in approximately 1 billion solar masses. So I'm actually quite a massive giant, at least 200 times more massive than the black hole in the Milky Way. But more recent studies and some more recent observations actually suggest that it's even bigger. It's possibly up to 9 billion solar masses or 2,000 times more massive than the Sagittarius A* in the Milky Way and two times more massive than the black hole in the center of M87 whose picture scientists took not so long ago. And because this galaxy is only about 20 to 30 million light years away from us, or basically it's closer than M87, in theory, if this is actually true, the black hole from this galaxy would actually appear at least twice as large as the black hole from M87, meaning that its picture would be even easier to take and would produce a lot more detail. And so hopefully the team from the Event Horizon Telescope will be able to produce another picture of a black hole sometimes in the future.

[00:05:20]Because as of today, they've only conducted some initial observations confirming its existence and confirming its location, but not recreating its image yet. But interestingly, despite its enormous size, it also seems to be kind of docile. It's not actually producing that many emissions and is only slowly snacking on some of the surrounding gas instead of having a massive feast which would produce incredibly bright X-rays. But I guess one day it might wake up again and thus become visible in a lot of different wavelengths. But, we also had some more recent discoveries about the galaxy itself because in 2024 and more recently in 2026, James Webb produced some of the new pictures and specifically focusing on the famous dust ring. And while previous telescopes showed this ring as a kind of a very smooth and very continuous structure, which is why a lot of scientists believed that this was maybe in this galaxy. But, according to Webb, that definitely does not seem to be the case because in high resolution, we actually see a lot of clumpiness and a lot [clears throat] of broken structures. And many of these clumps contain carbon-rich molecules such as polycyclic aromatic hydrocarbons, which in most galaxies represent building blocks for many new stars. As a matter of fact, almost every galaxy seen so far that contains these types of molecules is normally some kind of a starburst galaxy and produces a lot of bright emissions. But, surprisingly here, Sombrero Galaxy is not a hotbed for star formation and actually produces less stars than the Milky Way. It actually seems to be about half as efficient in star production as our own galaxy. And that's a bit of a mystery. It seems to have a lot of ingredients and it definitely seems to have the right structure, but for some reason it's just not very active, which is yet another mystery of this somewhat strange Mexican Hat. But, one of the biggest discoveries and I guess one of the biggest aha moments [clears throat] came from the recent observations of the Dark Energy Camera, whose main purpose is to look at various galaxies and to try to discover as much about them as possible in order to study the dark energy. And so here the DECam, as it's known, along with the Hubble telescope, managed to capture the galactic halo with a lot of detail, showing that it stretches over three times the width of the galaxy itself. This is essentially what you're seeing in this video. But on top of this, they also found a faint sweeping stellar stream extending to the south, which in most cases represents some kind of an ancient collision or some kind of a leftover from a destroyed galaxy. And so these are definitely stars that have been torn away from another galaxy, implying ancient mergers. And so by combining this with the discovery that the halo seems to contain metal-rich stars, it essentially points at just one conclusion. Billions of years ago, the Sombrero Galaxy has gone through a major galactic merger between two relatively massive galaxies, and it was most likely this collision that first of all created a giant elliptical halo, while also creating the disc-like shape in the center. And so all of these halo stars potentially represent the leftover from the destroyed galaxy, which was maybe just a little bit smaller. With a central disc galaxy representing the larger, more massive giant that seems to shred any galaxy that gets too close. And so this is definitely one of the more important galaxies known to us because it represents a natural laboratory for studying various astronomical effects.

[00:08:56]For example, we know it contains nearly 2,000 globular clusters, which is 10 times more than the Milky Way. And because many of them are also very ancient, by studying these clusters, we can maybe one day figure out how they usually form, while also helping us understand how galaxies and galactic shapes evolve following collisions, and how some galaxies acquire incredibly massive black holes. But this galaxy still has quite a few mysteries too. For example, a decade ago, astronomers discovered unusual radiation coming from the core in terahertz frequencies, and it seems to not fit any modern model in how these frequencies are usually produced. And so here these emissions do not seem to come from any dust or any nebula and do not seem to come from synchrotron radiation usually produced by fast-moving electrons. Or just to rephrase this, these strange emissions in 850 micrometers in wavelength that seem to come from the center of the galaxy do not have any physical explanation at the moment. And though it could be coming from the black hole, it could also be coming from some really bizarre star formation phenomenon or some other very powerful interaction we've never seen before. And so, essentially, even after several centuries and years and years of observations, this relatively close galaxy is still hiding quite a lot of mysteries. But, the more we look at it, the more we understand how the universe seems to work and the more we learn about how galaxies tend to merge, how black holes grow larger, and how some galaxies end up with very bizarre shapes. And so, what started as a fuzzy object in a 1781 notebook turned out to be a massive hybrid survivor of a cosmic collision that seems to also contain one of the largest and most massive black holes known to us, at least in the local neighborhood. This is actually the closest over massive black hole to the Milky Way. [music] And on that note, well, once we discover something else, we'll come back and talk about this galaxy in some of the future videos. Until then, thank you for watching, subscribe, come back tomorrow to learn something else, support the show on Patreon where you can find additional videos, videos without any ads, and can DM me directly, or by joining channel membership that grants you early access. You can also support the show by buying a wonderful person t-shirt in the description below. Stay wonderful. I'll see you tomorrow. And as always, bye-bye.