Did NASA just observe the brightest burst of all-time?
1.9 billion years ago, a star's explosive death created a black hole. Its light just arrived at Earth. But did it set a cosmic record?
Swift’s X-Ray Telescope captured the afterglow of GRB 221009A about an hour after it was first detected. The bright rings form as a result of X-rays scattered from otherwise unobservable dust layers within our galaxy that lie in the direction of the burst.
(Credit: NASA/Swift/A. Beardmore (University of Leicester))
Key Takeaways
- 1.9 billion years ago, a massive star died in a spectacular explosion, producing a supernova, a gamma-ray burst, and likely a black hole in the process.
- On October 9, 2022, its light arrived here on Earth, including gamma-rays, X-rays, and an optical afterglow that still endures.
- But was it truly the brightest burst of all time? Although it's bright and impressive, it has a long way to go to set the ultimate energy record.
For most of us, the brightest object we’ll ever see is our Sun.
The Sun’s light is due to nuclear fusion, which primarily converts hydrogen into helium. When we measure the rotation rate of the Sun, we find that it’s one of the slowest rotators in the entire Solar System, taking from 25-to-33 days to make one 360-degree rotation, dependent on latitude. Emitting a near-constant 3.8 × 10^26 W of power, the Sun is the brightest thing most of us will ever see. Although many other sources are intrinsically brighter, they’re much farther away.
Delivering nearly 130,000 lumens per square meter to Earth, no other astronomical source compares.
The (modern) Morgan–Keenan spectral classification system, with the temperature range of each star class shown above it, in kelvin. The overwhelming majority of stars today are M-class stars, with only 1 known O- or B-class star within 25 parsecs. Our Sun is a G-class star. However, in the early Universe, almost all of the stars were O or B-class stars, with an average mass 25 times greater than average stars today.
But it’s not particularly intrinsically luminous; it’s simply nearby.
The central concentration of this young star cluster found in the heart of the Tarantula Nebula is known as R136, and contains many of the most massive stars known. Among them is R136a1, which comes in at about ~260 solar masses, making it the heaviest known star. All told, this is the largest star-forming region within our Local Group, and it will likely form hundreds of thousands of new stars that will bind together in a globular cluster, while the brightest stars within it shine several millions of times as bright as our Sun.
Massive, young, blue stars can shine millions of times as bright.
The two largest, brightest galaxies in the M81 Group, M81 (right) and M82 (left), are shown in the same frame in these 2013 and 2014 photos. In 2014, M82 experienced a supernova, visible in the 2014 (blue) image just above the galactic center.
During stellar cataclysms, like supernovae, dying stars can achieve ~ten billion solar luminosities.
The anatomy of a very massive star throughout its life, culminating in a Type II (core-collapse) Supernova when the core runs out of nuclear fuel. The final stage of fusion is typically silicon-burning, producing iron and iron-like elements in the core for only a brief while before a supernova ensues. The most massive core-collapse supernovae typically result in the creation of black holes, while the less massive ones create only neutron stars.
But some supernovae achieve — albeit temporarily — even greater brightnesses.
In a normal supernova, (left) there’s plenty of surrounding material preventing the core from becoming exposed, even years or decades after the explosion first occurs. However, with a Cow-like supernova, the copious material surrounding the stellar core is broken apart, exposing the core in short order, possibly related to the excessive brightness seen in such events.
During their final stages, stellar interiors get so hot that photons spontaneously produce electron-positron pairs.
Although many interactions are possible between charged particles and photons, at sufficiently high energies, those photons can behave as electron-positron pairs, which can drain a charged particle’s energy far more efficiently than simple scattering with mere photons. When photons convert to electron-positron pairs inside hot, massive stars, the pressure inside plummets, leading to a pair-instability supernova.
This matter-antimatter conversion triggers a superluminous pair-instability supernova.
This diagram illustrates the pair production process that astronomers once thought triggered the hypernova event known as SN 2006gy. When high-enough-energy photons are produced, they will create electron/positron pairs, causing a pressure drop and a runaway reaction that destroys the star. This event is known as a pair-instability supernova. Peak luminosities of a hypernova, also known as a superluminous supernova, are many times greater than that of any other, ‘normal’ supernova.
Cocooned, detonating stars and remnants can outshine them, albeit temporarily.
An event like AT2018cow, now known as either FBOTs or Cow-like events, is thought to be the result of a breakout shock from a cocooned supernova. With five such events now discovered, the hunt is on to uncover precisely what causes them, as well as what makes them so unique. “New physics,” which some had theorized, is entirely unnecessary to explain this class of objects.
But collimated jets emitted from hypernova events — already brilliantly luminous supernovae — outshine them all.
This artist’s impression shows a supernova and associated gamma-ray burst driven by a rapidly spinning neutron star with a very strong magnetic field — an exotic object known as a magnetar. Many of the most powerful cataclysms in the Universe are also powered by either an accreting black hole or a millisecond magnetar like this one, but some don’t produce gamma-ray bursts, but rather X-rays, along with them.
Fast rotations and magnetic fields collimate material, creating ultrarelativistic motions.
This illustration of superluminous supernova SN 1000+0216, the most distant supernova ever observed at a redshift of z=3.90, from when the Universe was just 1.6 billion years old, is the current record-holder for individual supernovae in terms of distance. In terms of brightness, it easily outshines an entire galaxy; in terms of power, it can rival most of the stars in the Universe, all combined together, for brief intervals.
They illuminate and ionize the surrounding particles, producing extremely energetic photons.
On October 9, 2022, a brilliant gamma-ray burst arrived at Earth.
This sequence constructed from Fermi Large Area Telescope data reveals the sky in gamma rays centered on the location of GRB 221009A. Each frame shows gamma rays with energies greater than 100 million electron volts (MeV), where brighter colors indicate a stronger gamma-ray signal. In total, they represent more than 10 hours of observations. The glow from the midplane of our Milky Way galaxy appears as a wide diagonal band. The image is about 20 degrees across.
At ~2 billion light-years distant, it’s an especially close, bright cataclysm.
This series of images taken by Swift’s Ultraviolet/Optical Telescope shows how the afterglow of GRB 221009A (circled) faded over the course of about 10 hours. Swift was behind the Earth when GRB 221009A occurred, but emerged from our planet’s shadow to capture these images of the afterglow. The explosion appeared in the constellation Sagitta and occurred about 1.9 billion years ago. The image is approximately 4 arcminutes across.
But it hasn’t outshone the current record-holder.
Illustration of a fast gamma-ray burst, long thought to occur from the merger of neutron stars. The gas-rich environment surrounding them could delay the arrival of the signal, but the mechanism that produces it could also cause a delay in the emission of the signal. Light and gravity should both travel, through the vacuum of space, at the same speed.
2008’s GRB 080319B peaked at 21 quadrillion times the Sun’s brightness.
The extremely luminous afterglow of GRB 080319B was imaged by Swift’s X-ray Telescope (left) and Optical/Ultraviolet Telescope (right). This was by far the brightest gamma-ray burst afterglow ever seen, peaking with a power output of 21 quadrillion (2.1 × 10^16) Suns.
Only merging black holes release greater energies.
A mathematical simulation of the warped space-time near two merging neutron stars that result in the creation of a black hole. The colored bands are gravitational-wave peaks and troughs, with the colors getting brighter as the wave amplitude increases. The strongest waves, carrying the greatest amount of energy, come just before and during the merger event itself. What occurs outside the event horizon is not practically affected by whether there is a ring singularity at the center, or some other, extended object that is non-singular.
Peaking at over 1049 Watts, they overpower all stars combined over millisecond timescales.
Although most galaxies have only a single supermassive black hole at their centers, some galaxies have two: a binary supermassive black hole. When these black holes inspiral and merge, they represent the most energetic events to occur in our cosmos since the Big Bang, and can outshine all the stars in the sky, combined, by a factor of many millions.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.
