If confirmed, this discovery would represent the widest reach ever seen for a black hole acting as a stellar kick-starter — enhancing star formation more than one million light-years away. (One light year is equal to 6 trillion miles.)
A black hole is an extremely dense object from which no light can escape. The black hole’s immense gravity pulls in surrounding gas and dust. Sometimes, black holes hinder star birth. Sometimes — like perhaps in this case — they increase star birth.
A quiet, starry night sky might not seem like a very spooky spectacle, but space can be a creepy place! Monsters lurk in the shadowy depths of the universe, sometimes hidden in plain sight. Many of them are invisible to our eyes, so we have to use special telescopes to see them. Read on to discover some of these strange cosmic beasts, but beware — sometimes fact is scarier than fiction.
Monster Black Holes ⚫
You know those nightmares where no matter how fast you try to run you never seem to get anywhere? Black holes are a sinister possible version of that dream — especially because they’re real! If you get too close to a black hole,there is no possibility of escape.
This fiendish specter lives in the center of the Milky Way, haunting our galaxy’s supermassive black hole. But it’s not as scary as it looks! Our SOFIA observatory captured streamlines tracing a magnetic field that appears to be luring most of the material quietly into orbit around the black hole. In other galaxies, magnetic fields seem to be feeding material into hungry black holes — beware! Magnetic fields might be the answer to why some black holes are starving while others are feasting.
Bats in the Belfry 🦇
The universe has bats in the attic! Hubble spotted the shadow of a giant cosmic bat in the Serpens Nebula. Newborn stars like the one at the center of the bat, called HBC 672, are surrounded by disks of material, which are hard to study directly. The shadows they cast, like the bat, can clue scientists in on things like the disk’s size and density. Our solar system formed from the same type of disk of material, but we can only see the end result of planet building here — we want to learn more about the process!
Trick-or-treat! Add a piece of glowing cosmic candy to your Halloween haul, courtesy of Hubble! This image shows the Saturn Nebula, formed from the outer layers ejected by a dying star, destined to be recycled into later generations of stars and planets. Our Sun will experience a similar fate in around five billion years.
The universe is brimming with galaxies, but it’s also speckled with some enormous empty pockets of space, too. These giant ghost towns, called voids, may be some of the largest things in the cosmos, and since the universe is expanding, galaxies are racing even farther away from each other all the time! Be grateful for your place in space — the shadowy patches of the universe are dreadful lonely scenes.
About 45 million light-years away, in another corner of the cosmos, lies spiral galaxy NGC 1097. Though this Hubble Space Telescope image zooms in toward the core, the galaxy’s vast spiral arms span over 100,000 light-years as they silently sweep through space. At the heart of this galaxy lurks a black hole that is about 100 million times as massive as the Sun.
The supermassive black hole is voraciously eating up surrounding matter, which forms a doughnut-shaped ring around it. Matter that’s pulled into the black hole releases powerful radiation, making the star-filled center of the galaxy even brighter. Hubble’s observations have led to the discovery that while the material that is drawn toward NGC 1097’s black hole may be doomed to die, new stars are bursting into life in the ring around it.
This sparkling spiral galaxy is especially interesting to both professional scientists and amateur astronomers. It is a popular target for supernova hunters ever since the galaxy experienced three supernovas in relatively rapid succession — just over a decade, between 1992 and 2003. Scientists are intrigued by the galaxy’s satellites — smaller “dwarf” galaxies that orbit NGC 1097 like moons. Studying this set of galaxies could reveal new information about how galaxies interact with each other and co-evolve.
Confused? Don’t be! We get a ton of questions about Fermi and figured we’d take a moment to answer a few of them here.
1. Who was this Fermi guy?
The Fermi telescope was named after Enrico Fermi in recognition of his work on how the tiny particles in space become accelerated by cosmic objects, which is crucial to understanding many of the objects that his namesake satellite studies.
Enrico Fermi was an Italian physicist and Nobel Prize winner (in 1938) who immigrated to the United States to be a professor of physics at Columbia University, later moving to the University of Chicago.
Original image courtesy Argonne National Laboratory
Over the course of his career, Fermi was involved in many scientific endeavors, including the Manhattan Project, quantum theory and nuclear and particle physics. He even engineered the first-ever atomic reactor in an abandoned squash court (squash is the older, English kind of racquetball) at the University of Chicago.
There are a number of other things named after Fermi, too: Fermilab, the Enrico Fermi Nuclear Generating Station, the Enrico Fermi Institute and more. (He’s kind of a big deal in the physics world.)
Fermi even had something to say about aliens! One day at lunch with his buddies, he wondered if extraterrestrial life existed outside our solar system, and if it did, why haven’t we seen it yet? His short conversation with friends sparked decades of research into this idea and has become known as the Fermi Paradox — given the vastness of the universe, there is a high probability that alien civilizations exist out there, so they should have visited us by now.
2. So, does the Fermi telescope look for extraterrestrial life?
Fermi does not look for aliens, extraterrestrial life or anything of the sort! If aliens were to come our way, Fermi would be no help in identifying them, and they might just slip right under Fermi’s nose. Unless, of course, those alien spacecraft were powered by processes that left behind traces of gamma rays.
Fermi detects gamma rays, the highest-energy form of light, which are often produced by events so far away the light can take billions of years to reach Earth. The satellite sees pulsars, active galaxies powered by supermassive black holes and the remnants of exploding stars. These are not your everyday stars, but the heavyweights of the universe.
Nope. In movies and comic books, the hero has a tragic backstory and a brush with death, only to rise out of some radioactive accident stronger and more powerful than before. In reality, that much radiation would be lethal.
In fact, as a form of radiation, gamma rays are dangerous for living cells. If you were hit with a huge amount of gamma radiation, it could be deadly — it certainly wouldn’t be the beginning of your superhero career.
5. That sounds bad…does that mean if a gamma-ray burst hit Earth, it would wipe out the planet and destroy us all?
Thankfully, our lovely planet has an amazing protector from gamma radiation: an atmosphere. That is why the Fermi telescope is in orbit; it’s easier to detect gamma rays in space!
Gamma-ray bursts are so far away that they pose no threat to Earth. Fermi sees gamma-ray bursts because the flash of gamma rays they release briefly outshines their entire home galaxies, and can sometimes outshine everything in the gamma-ray sky.
If a habitable planet were too close to one of these explosions, it is possible that the jet emerging from the explosion could wipe out all life on that planet. However, the probability is extremely low that a gamma-ray burst would happen close enough to Earth to cause harm. These events tend to occur in very distant galaxies, so we’re well out of reach.
We hope that this has helped to clear up a few misconceptions about the Fermi Gamma-ray Space Telescope. It’s a fantastic satellite, studying the craziest extragalactic events and looking for clues to unravel the mysteries of our universe!
We’re going to talk about some of the amazing new things NICER is showing us about black holes. But first, let’s talk about black holes — how do they work, and where do they come from? There are two important types of black holes we’ll talk about here: stellar and supermassive. Stellar mass black holes are three to dozens of times as massive as our Sun while supermassive black holes can be billions of times as massive!
Stellar black holes begin with a bang — literally! They are one of the possible objects left over after a large star dies in a supernova explosion. Scientists think there are as many as a billion stellar mass black holes in our Milky Way galaxy alone!
Supermassive black holes have remained rather mysterious in comparison. Data suggest that supermassive black holes could be created when multiple black holes merge and make a bigger one. Or that these black holes formed during the early stages of galaxy formation, born when massive clouds of gas collapsed billions of years ago. There is very strong evidence that a supermassive black hole lies at the center of all large galaxies, as in our Milky Way.
Imagine an object 10 times more massive than the Sun squeezed into a sphere approximately the diameter of New York City — or cramming a billion trillion people into a car! These two examples give a sense of how incredibly compact and dense black holes can be.
Because so much stuff is squished into such a relatively small volume, a black hole’s gravity is strong enough that nothing — not even light — can escape from it. But if light can’t escape a dark fate when it encounters a black hole, how can we “see” black holes?
Scientists can’t observe black holes directly, because light can’t escape to bring us information about what’s going on inside them. Instead, they detect the presence of black holes indirectly — by looking for their effects on the cosmic objects around them. We see stars orbiting somethingmassive but invisible to our telescopes, or even disappearing entirely!
When a star approaches a black hole’s event horizon — the point of no return — it’s torn apart. A technical term for this is “spaghettification” — we’re not kidding! Cosmic objects that go through the process of spaghettification become vertically stretched and horizontally compressed into thin, long shapes like noodles.
Scientists can also look for accretion disks when searching for black holes. These disks are relatively flat sheets of gas and dust that surround a cosmic object such as a star or black hole. The material in the disk swirls around and around, until it falls into the black hole. And because of the friction created by the constant movement, the material becomes super hot and emits light, including X-rays.
At last — light! Different wavelengths of light coming from accretion disks are something we can see with our instruments. This reveals important information about black holes, even though we can’t see them directly.
So what has NICER helped us learn about black holes? One of the objects this instrument has studied during its time aboard the International Space Station is the ever-so-forgettably-named black hole GRS 1915+105, which lies nearly 36,000 light-years — or 200 million billion miles — away, in the direction of the constellation Aquila.
Scientists have found disk winds — fast streams of gas created by heat or pressure — near this black hole. Disk winds are pretty peculiar, and we still have a lot of questions about them. Where do they come from? And do they change the shape of the accretion disk?
It’s been difficult to answer these questions, but NICER is more sensitive than previous missions designed to return similar science data. Plus NICER often looks at GRS 1915+105 so it can see changes over time.
NICER’s observations of GRS 1915+105 have provided astronomers a prime example of disk wind patterns, allowing scientists to construct models that can help us better understand how accretion disks and their outflows around black holes work.
NICER has also collected data on a stellar mass black hole with another long name — MAXI J1535-571 (we can call it J1535 for short) — adding to information provided by NuSTAR, Chandra, and MAXI. Even though these are all X-ray detectors, their observations tell us something slightly different about J1535, complementing each other’s data!
This rapidly spinning black hole is part of a binary system, slurping material off its partner, a star. A thin halo of hot gas above the disk illuminates the accretion disk and causes it to glow in X-ray light, which reveals still more information about the shape, temperature, and even the chemical content of the disk. And it turns out that J1535’s disk may be warped!
Image courtesy of NRAO/AUI and Artist: John Kagaya (Hoshi No Techou)
NICER primarily studies neutron stars — it’s in the name! These are lighter-weight relatives of black holes that can be formed when stars explode. But NICER is also changing what we know about many types of X-ray sources. Thanks to NICER’s efforts, we are one step closer to a complete picture of black holes. And hey, that’s pretty nice!