Black Holes

This gallery gathers together visualizations and narrated videos about black holes. A black hole is a celestial object whose gravity is so intense that even light cannot escape it. Astronomers observe two main types of black holes. Stellar-mass black holes contain three to dozens of times the mass of our Sun. They form when the cores of very massive stars run out of fuel and collapse under their own weight, compressing large amounts of matter into a tiny space. Supermassive black holes, with masses up to billions of times the Sun’s, can be found at the centers of most big galaxies. Although a black hole does not emit light, matter falling toward it collects in a hot, glowing accretion disk that astronomers can detect.

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Most Recent Black Hole Stories

  • NASA's Field Guide to Black Holes
    2021.04.12
    Thinking about doing some black hole watching the next time you’re on an intergalactic vacation, but you’re not quite sure where to start? Well, look no further! This series of videos shows you everything you need to know. With topics ranging from basic black holes, to fancy black holes, to giant black holes and their companions, you’ll be more than ready for your next adventure. In addition to the videos, you can also download a printable guide that has even more information. Note: While these videos can be shared in their entirety without permission, their music has been licensed and may not be excised or remixed in other products.
  • NASA Visualization Probes the Doubly Warped World of Binary Black Holes
    2021.04.15
    A pair of orbiting black holes millions of times the Sun’s mass perform a hypnotic dance in this NASA visualization. The movie traces how the black holes distort and redirect light emanating from the maelstrom of hot gas – called an accretion disk – that surrounds each one. Viewed from near the orbital plane, each accretion disk takes on a characteristic warped look. But as one passes in front of the other, the gravity of the foreground black hole transforms its partner into a rapidly changing sequence of arcs. These distortions play out as light from the accretion disks navigates the tangled fabric of space and time near the black holes. The simulated binary contains two supermassive black holes, a larger one with 200 million solar masses and a smaller companion weighing half as much. Astronomers think that in binary systems like this, both black holes could maintain accretion disks for millions of years. The disks have different colors, red and blue, to make it easier to track the light sources, but the choice also reflects reality. Gas orbiting lower-mass black holes experiences stronger effects that produce higher temperatures. For these masses, both accretion disks would actually emit most of their light in the UV, with the blue disk reaching a slightly higher temperature. Visualizations like this help scientists picture the fascinating consequences of extreme gravity’s funhouse mirror. Seen nearly edgewise, the accretion disks look noticeably brighter on one side. Gravitational distortion alters the paths of light coming from different parts of the disks, producing the warped image. The rapid motion of gas near the black hole modifies the disk’s luminosity through a phenomenon called Doppler boosting – an effect of Einstein’s relativity theory that brightens the side rotating toward the viewer and dims the side spinning away. The visualization also shows a more subtle phenomenon called relativistic aberration. The black holes appear smaller as they approach the viewer and larger when moving away. These effects disappear when viewing the system from above, but new features emerge. Both black holes produce small images of their partners that circle around them each orbit. Looking closely, it’s clear that these images are actually edge-on views. To produce them, light from the black holes must be redirected by 90 degrees, which means we’re observing the black holes from two different perspectives – face on and edge on – at the same time. Zooming into each black hole reveals multiple, increasingly distorted images of its partner. The visualization, created by astrophysicist Jeremy Schnittman at NASA's Goddard Space Flight Center in Greenbelt, Maryland, involved computing the path taken by light rays from the accretion disks as they made their way through the warped space-time around the black holes. On a modern desktop computer, the calculations needed to make the movie frames would have taken about a decade. So Schnittman teamed up with Goddard data scientist Brian P. Powell to use the Discover supercomputer at the NASA Center for Climate Simulation. Using just 2% of Discover’s 129,000 processors, these computations took about a day. Astronomers expect that, one day, they’ll be able to detect gravitational waves – ripples in space-time – produced when two supermassive black holes in a system much like the one Schnittman depicted spiral together and merge.
  • Hubble Uncovers Concentration of Small Black Holes
    2021.02.11
    Astronomers on the hunt for an intermediate-mass black hole at the heart of the globular cluster NGC 6397, found something they weren’t expecting: a concentration of smaller black holes lurking there instead of one massive black hole. For more information, visit https://nasa.gov/hubble. Music Credits: "Glass Ships" by Chris Constantinou [PRS] and Paul Frazer [PRS] via Killer Tracks [BMI] and Universal Production Music. Visual Credits: Artist’s Impression of the Black Hole Concentration in NGC 6397 Video credit: ESA/Hubble, N. Bartmann Callout of the Black Hole Concentration in NGC 6397 Video credit: ESA/Hubble, N. Bartmann Artist Rendition of Gaia Spacecraft Image credit: ESA, C. Carreau
  • Swift Links Neutrino to Star-destroying Black Hole
    2021.02.22
    For only the second time, astronomers have linked an elusive particle called a high-energy neutrino to an object outside our galaxy. Using ground- and space-based facilities, including NASA’s Neil Gehrels Swift Observatory, they traced the neutrino to a black hole tearing apart a star, a rare cataclysmic occurrence called a tidal disruption event. Neutrinos are fundamental particles that far outnumber all the atoms in the universe but rarely interact with other matter. Astrophysicists are particularly interested in high-energy neutrinos, which have energies up to 1,000 times greater than those produced by the most powerful particle colliders on Earth. They think the most extreme events in the universe, like violent galactic outbursts, accelerate particles to nearly the speed of light. Those particles then collide with light or other particles to generate high-energy neutrinos. The first confirmed high-energy neutrino source, announced in 2018, was a type of active galaxy called a blazar. Tidal disruption events occur when an unlucky star strays too close to a black hole. Gravitational forces create intense tides that break the star apart into a stream of gas. The trailing part of the stream escapes the system, while the leading part swings back around, surrounding the black hole with a disk of debris. In some cases, the black hole launches fast-moving particle jets. Scientists hypothesized that tidal disruptions would produce high-energy neutrinos within such particle jets. They also expected the events would produce neutrinos early in their evolution, at peak brightness, whatever the particles’ production process. Tidal disruption event AT2019dsg was discovered on April 9, 2019, by the Zwicky Transient Facility (ZTF), a robotic camera at Caltech’s Palomar Observatory in Southern California. The event occurred over 690 million light-years away in a galaxy called 2MASX J20570298+1412165, located in the constellation Delphinus. As part of a routine follow-up survey of tidal disruptions, scientists requested visible, ultraviolet, and X-ray observations with Swift. They also took X-ray measurements using the European Space Agency’s XMM-Newton satellite and radio measurements with facilities including the National Radio Astronomy Observatory’s Karl G. Jansky Very Large Array in Socorro, New Mexico, and the South African Radio Astronomy Observatory's MeerKAT telescope. Peak brightness came and went in May. No clear jet appeared. According to theoretical predictions, AT2019dsg was looking like a poor neutrino candidate. Then, on Oct. 1, 2019, the National Science Foundation’s IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station in Antarctica detected a high-energy neutrino called IC191001A and backtracked along its trajectory to a location in the sky. About seven hours later, ZTF noted that this same patch of sky included AT2019dsg. Astronomers think there is only one chance in 500 that the tidal disruption is not the neutrino’s source. Because the detection came about five months after the event reached peak brightness, it raises questions about when and how these occurrences produce neutrinos.
  • Black Hole Accretion Disk Visualization
    2019.09.25
    This new visualization of a black hole illustrates how its gravity distorts our view, warping its surroundings as if seen in a carnival mirror. The visualization simulates the appearance of a black hole where infalling matter has collected into a thin, hot structure called an accretion disk. The black hole’s extreme gravity skews light emitted by different regions of the disk, producing the misshapen appearance. Bright knots constantly form and dissipate in the disk as magnetic fields wind and twist through the churning gas. Nearest the black hole, the gas orbits at close to the speed of light, while the outer portions spin a bit more slowly. This difference stretches and shears the bright knots, producing light and dark lanes in the disk. Viewed from the side, the disk looks brighter on the left than it does on the right. Glowing gas on the left side of the disk moves toward us so fast that the effects of Einstein’s relativity give it a boost in brightness; the opposite happens on the right side, where gas moving away us becomes slightly dimmer. This asymmetry disappears when we see the disk exactly face on because, from that perspective, none of the material is moving along our line of sight. Closest to the black hole, the gravitational light-bending becomes so excessive that we can see the underside of the disk as a bright ring of light seemingly outlining the black hole. This so-called “photon ring” is composed of multiple rings, which grow progressively fainter and thinner, from light that has circled the black hole two, three, or even more times before escaping to reach our eyes. Because the black hole modeled in this visualization is spherical and non-rotating, the photon ring looks nearly circular and identical from any viewing angle. Inside the photon ring is the black hole’s shadow, an area roughly twice the size of the event horizon — its point of no return. This visualization is “mass invariant,” which means it can represent a black hole of any mass. The size of the black hole's shadow is proportional to its mass, but so is the size of the accreetion disk, so its properties scale accordingly. Simulations and movies like these really help us visualize what Einstein meant when he said that gravity warps the fabric of space and time.
  • NASA's Guide To Black Hole Safety
    2019.09.23
    Have you ever thought about visiting a black hole? We sure hope not. However, if you're absolutely convinced that a black hole is your ideal vacation spot, watch this video before you blast off to learn more about them and (more importantly) how to stay safe. You can also download a handy safety brochure, watch short clips to learn different things about black holes, and even get some short glimpses into the lives of black holes and the explorers that want to visit them.
  • Mysterious ‘Cow’ Blast Studied with NASA Telescopes
    2019.01.10
    A brief and unusual flash spotted in the night sky on June 16, 2018, puzzled astronomers and astrophysicists across the globe. The event, called AT2018cow and nicknamed “the Cow” after the coincidental last letters of its official designation, is unlike any celestial outburst ever seen before, prompting multiple theories about its source. Over three days, the Cow produced a sudden explosion of light at least 10 times brighter than a typical supernova, and then it faded over the next few months. This unusual event occurred near a star-forming galaxy known as CGCG 137-068, located about 200 million light-years away in the constellation Hercules. Using data from multiple NASA missions, including the Neil Gehrels Swift Observatory and the Nuclear Spectroscopic Telescope Array (NuSTAR) and ESA’s (the European Space Agency's) XMM-Newton and INTEGRAL missions, two groups have provided possible explanations for the Cow’s origins. One group argues that the Cow is a monster black hole shredding a passing star. The second group hypothesizes that it is a supernova — a stellar explosion — that gave birth to a black hole or a neutron star. Whatever its source, the Cow represents a stellar death scenario not previously seen.
  • Zoom In on Galaxy M87
    2019.09.24
    This movie zooms into galaxy M87 using real visible light, X-ray and radio pictures of the galaxy, its jet of high-speed particles, and the shadow of its central black hole.
  • New Simulation Sheds Light on Spiraling Supermassive Black Holes
    2018.10.02
    A new model is bringing scientists a step closer to understanding the kinds of light signals produced when two supermassive black holes, which are millions to billions of times the mass of the Sun, spiral toward a collision. For the first time, a new computer simulation that fully incorporates the physical effects of Einstein’s general theory of relativity shows that gas in such systems will glow predominantly in ultraviolet and X-ray light. The new simulation shows three orbits of a pair of supermassive black holes only 40 orbits from merging. The models reveal the light emitted at this stage of the process may be dominated by UV light with some high-energy X-rays, similar to what’s seen in any galaxy with a well-fed supermassive black hole. Three regions of light-emitting gas glow as the black holes merge, all connected by streams of hot gas: a large ring encircling the entire system, called the circumbinary disk, and two smaller ones around each black hole, called mini disks. All these objects emit predominantly UV light. When gas flows into a mini disk at a high rate, the disk’s UV light interacts with each black hole’s corona, a region of high-energy subatomic particles above and below the disk. This interaction produces X-rays. When the accretion rate is lower, UV light dims relative to the X-rays. Based on the simulation, which ran on the National Center for Supercomputing Applications’ Blue Waters supercomputer at the University of Illinois at Urbana-Champaign, the researchers expect X-rays emitted by a near-merger will be brighter and more variable than X-rays seen from single supermassive black holes. The pace of the changes links to both the orbital speed of gas located at the inner edge of the circumbinary disk as well as that of the merging black holes.
  • NASA's Fermi Links Cosmic Neutrino to Monster Black Hole
    2018.07.12
    For the first time ever, scientists using NASA’s Fermi Gamma-ray Space Telescope have found the source of a high-energy neutrino from outside our galaxy. This neutrino travelled 3.7 billion years at nearly light speed before being detected on Earth -- farther than any other neutrino we know the origin of. High-energy neutrinos are hard-to-catch particles that scientists think are created by the most powerful events in the cosmos, like galaxy mergers and material falling onto supermassive black holes. They travel a whisker shy of the speed of light and rarely interact with other matter, so they can travel unimpeded across billions of light-years. On Sept. 22, 2017, the IceCube Neutrino Observatory at the South Pole detected signs of a neutrino striking the Antarctic ice with an energy of about 300 trillion electron volts -- more than 45 times the energy achievable in the most powerful particle accelerator on Earth. This high energy strongly suggested that the neutrino had to be from beyond our solar system. Backtracking the path through IceCube indicated where in the sky the neutrino came from, and automated alerts notified astronomers around the globe to search this region for flares or outbursts that could be associated with the event. Data from Fermi’s Large Area Telescope revealed enhanced gamma-ray emission from a well-known active galaxy at the time the neutrino arrived. This active galaxy is a type called a blazar, where a supermassive black hole with millions to billions of times the Sun’s mass that blasts particle jets outward in opposite directions at nearly the speed of light. Blazars are especially bright and active because one of these jets happens to point almost directly toward Earth. Fermi showed that at the time of the neutrino detection, the blazar TXS 0506+056 was the most active it had been in a decade. The discovery is a giant leap forward in a growing field called multimessenger astronomy, where new cosmic signals like neutrinos and gravitational waves are definitively linked to sources that emit light.
  • Star Gives Birth to Possible Black Hole in Hubble and Spitzer Images
    2017.05.25
    A team of astronomers at The Ohio State University watched a star disappear and possibly become a black hole. Instead of becoming a black hole through the expected process of a supernova, the black hole candidate formed through a "failed supernova." The team used NASA's Hubble and Spitzer Space Telescopes and the Large Binocular Telescope to observe and monitor the star throughout the past decade. If confirmed, this would be the first time anyone has witnessed the birth of a black hole and the first discovery of a failed supernova. Read the NASA web feature here. Find the full image release package at HubbleSite.org. Read the full science paper in the Monthly Notices of the Royal Astronomical Society.
  • Swift Charts a Star's 'Death Spiral' into Black Hole
    2017.03.20
    Some 290 million years ago, a star much like the sun wandered too close to the central black hole of its galaxy. Intense tides tore the star apart, which produced an eruption of optical, ultraviolet and X-ray light that first reached Earth in 2014. Now, a team of scientists using observations from NASA's Swift satellite have mapped out how and where these different wavelengths were produced in the event, named ASASSN-14li, as the shattered star's debris circled the black hole. Astronomers discovered brightness changes in X-rays that occurred about a month after similar changes were observed in visible and UV light, which means the optical and UV emission arose far from the black hole, likely where elliptical streams of orbiting matter crashed into each other. ASASSN-14li was discovered Nov. 22, 2014, in images obtained by the All Sky Automated Survey for SuperNovae (ASASSN), which includes robotic telescopes in Hawaii and Chile. Follow-up observations with Swift's X-ray and Ultraviolet/Optical telescopes began eight days later and continued every few days for the next nine months. ASASSN-14li was produced when a sun-like star wandered too close to a 3-million-solar-mass black hole. A star grazing a black hole with 10,000 or more times the sun's mass experiences enormous tides that tear it into a stream of debris. Astronomers call this a tidal disruption event. Matter falling toward a black hole collects into a spinning accretion disk, where it becomes compressed and heated before eventually spilling over the black hole's event horizon, the point beyond which nothing can escape and astronomers cannot observe. Tidal disruption flares carry important information about how this debris initially settles into an accretion disk.
  • Hubble Detects a Rogue Supermassive Black Hole
    2017.03.23
    The Hubble Space Telescope captured an image of a quasar named 3C 186 that is offset from the center of its galaxy. Astronomers hypothesize that this supermassive black hole was jettisoned from the center of its galaxy by the recoil from gravitational waves produced by the merging of two supermassive black holes. Read the press release here - https://www.nasa.gov/feature/goddard/2017/feature/gravitational-wave-kicks-monster-black-hole-out-of-galactic-core Download the Hubble images here - http://hubblesite.org/news_release/news/2017-12 Read the science paper here - http://imgsrc.hubblesite.org/hvi/uploads/science_paper/file_attachment/231/3c186.pdf
  • Blazar Animations
    2018.07.12
    This animation shows the central supermassive black hole of a blazar. The black hole is surrounded by a bright accretion disk and a darker torus of gas and dust. A bright jet of particles emerges from above and below the black hole. Collisions within the jet produce high-energy photons such as gamma rays. A flare from the blazar results in an additional burst of gamma rays and neutrinos.
  • Milky Way Center in Multiple Wavelengths
    2018.06.04
    Our solar system and sun is located inside a pancake shaped galaxy. Imagine a scale model where the plane of the Milky Way is a DVD, and the central bulge is a ping pong ball glued in the center. It is this narrow plane that we see across the sky on a sufficiently dark night from Earth, from our vantage point inside it. Dust blocks much of our view. But at other wavelengths astronomers can probe the heart of our galaxy. The center of our Milky Way Galaxy, located 26,000 light-years away, houses a black hole as massive as a million suns, surrounded by very dense nest of stars and bright clouds. The density of stars in the innermost regions of the Milky Way is up to one million times greater than in our portion of the galaxy. This region contains extreme and unusual conditions that can influence the types of stars that reside there. The density of stars and clouds creates streaming patterns. There are large massive star clusters that cannot not be found outside that region. The radiation environment is intense in the galactic center. The near-infrared image (Hubble) shows the knots of cloud edges and emission that mark the plane of our galaxy. The mid-infrared image (Spitzer) highlights the clouds of gas and dust and star forming regions. The X-ray image (Chandra) tracks the most luminous and powerful stars in the area conspicuously revealing the galactic center region itself - including the million-solar mass black hole at the very hub of our galaxy. In addition, several other X-ray emitting locations can be seen, linked to massive star clusters.
  • Spiral Galaxy M106
    2019.02.11
    This portrait of nearby galaxy M106 is a composite of separate exposures acquired by various instruments on NASA’s Hubble Space Telescope as well as ground-based telescopes. It shows the active galaxy’s chaotic center, where large amounts of gas are thought to be falling into and fueling a supermassive black hole. In addition to the starry arms we typically see in spiral galaxies, this image shows red “anomalous arms” of hot gas. Astronomers think the gas is being expelled from the galaxy’s active central nucleus.

    Cepheid variable stars in this galaxy were used to refine the cosmic “distance ladder,” which helps us to understand the vast distances of deep space, and how objects there relate to each other in spacetime. Certain Cepheids have a regular cycle of brightness changes, and this special property of these stars reveals how far away they are from us, providing benchmarks for measuring other objects in the universe.

    The image was created by astrophotographer Robert Gendler, who is not a professional astronomer but a civilian who took an interest in space and has been photographing the night sky for decades. He used publicly available Hubble data, combined with his own work and that of another astrophotographer, Jay GaBany, to create this hybrid image.

  • Swift, TESS Catch Eruptions from an Active Galaxy
    2021.01.12
    Using data from facilities including NASA’s Neil Gehrels Swift Observatory and Transiting Exoplanet Survey Satellite (TESS), scientists have studied 20 instances and counting of regular outbursts of an event called ASASSN-14ko. Astronomers classify galaxies with unusually bright and variable centers as active galaxies. These objects can produce much more energy than the combined contribution of all their stars, including higher-than-expected levels of visible, ultraviolet, and X-ray light. Astrophysicists think the extra emission comes from near the galaxy’s central supermassive black hole, where a swirling disk of gas and dust accumulates and heats up because of gravitational and frictional forces. The black hole slowly consumes the material, which creates random fluctuation in the disk’s emitted light. But astronomers are interested in finding active galaxies with flares that happen at regular intervals, which might help them identify and study new phenomena and events. ASASSN-14ko was first detected on Nov. 14, 2014, by the All-Sky Automated Survey for Supernovae (ASAS-SN), a global network of 20 robotic telescopes. It occurred in ESO 253-3, an active galaxy over 570 million light-years away in the southern constellation Pictor. At the time, astronomers thought the outburst was most likely a supernova, a one-time event that destroys a star. Six years later, scientists examined the ESO 253-3 ASAS-SN light curve, or the graph of its brightness over time, and noticed a series of evenly spaced flares – a total of 17, all separated by 114 days. Each flare reaches its peak brightness in about five days, then steadily dims. They predicted that the galaxy would flare again on May 17, 2020, so they coordinated joint observations with ground- and space-based facilities, including multiwavelength measurements with Swift. ASASSN-14ko erupted right on schedule. Subsequent flares were predicted and observed on Sept. 7 and Dec. 20. Using measurements of these and previous flares from ASAS-SN, TESS, Swift and other observatories, including NASA’s NuSTAR and the European Space Agency’s XMM-Newton, scientists propose the repeating flares are most likely a partial tidal disruption event. A tidal disruption event occurs when an unlucky star strays too close to a black hole. Gravitational forces create intense tides that break the star apart into a stream of gas. The trailing part of the stream escapes the system, while the leading part swings back around the black hole. Astronomers see bright flares from these events when the shed gas strikes the black hole’s accretion disk. In this case, the astronomers suggest that one of the galaxy’s supermassive black holes, one with about 78 million times the Sun’s mass, partially disrupts an orbiting giant star. The star's orbit isn’t circular, and each time it passes closest to the black hole, it bulges outward, shedding mass but not completely breaking apart. Every encounter strips away an amount of gas equal to about three times the mass of Jupiter.

Significant Black Hole Stories

  • NICER Charts the Area Around a New Black Hole
    2019.01.30
    Scientists have mapped the environment surrounding a black hole that is 10 times the mass of the Sun using NASA’s Neutron star Interior Composition Explorer (NICER) payload aboard the International Space Station. NICER detected X-ray light from a recently discovered black hole, called MAXI J1820+070 (J1820 for short), as it consumed material from a companion star. Waves of X-rays formed "light echoes" that reflected off the swirling gas near the black hole and revealed changes in the environment’s size and shape. A black hole can siphon gas from a nearby star and into a ring of material called an accretion disk that glows in X-rays. Above this disk is the corona, a region of subatomic particles that glows in higher-energy X-rays. Astrophysicists want to better understand how the inner edge of the accretion disk and the corona change in size and shape as a black hole accretes material from its companion star. If they can understand how and why these changes occur in stellar-mass black holes over a period of weeks, they could shed light on how supermassive black holes evolve over millions of years and how they affect the galaxies in which they reside. One method used to chart those changes is called X-ray reverberation mapping, which uses X-ray reflections in much the same way sonar uses sound waves to map undersea terrain. From 10,000 light-years away, the scientists estimated that the corona contracted vertically from roughly 100 to 10 miles — that’s like seeing something the size of a blueberry shrink to something the size of a poppy seed at the distance of Pluto.
  • New Simulation Sheds Light on Spiraling Supermassive Black Holes
    2018.10.02
    A new model is bringing scientists a step closer to understanding the kinds of light signals produced when two supermassive black holes, which are millions to billions of times the mass of the Sun, spiral toward a collision. For the first time, a new computer simulation that fully incorporates the physical effects of Einstein’s general theory of relativity shows that gas in such systems will glow predominantly in ultraviolet and X-ray light. The new simulation shows three orbits of a pair of supermassive black holes only 40 orbits from merging. The models reveal the light emitted at this stage of the process may be dominated by UV light with some high-energy X-rays, similar to what’s seen in any galaxy with a well-fed supermassive black hole. Three regions of light-emitting gas glow as the black holes merge, all connected by streams of hot gas: a large ring encircling the entire system, called the circumbinary disk, and two smaller ones around each black hole, called mini disks. All these objects emit predominantly UV light. When gas flows into a mini disk at a high rate, the disk’s UV light interacts with each black hole’s corona, a region of high-energy subatomic particles above and below the disk. This interaction produces X-rays. When the accretion rate is lower, UV light dims relative to the X-rays. Based on the simulation, which ran on the National Center for Supercomputing Applications’ Blue Waters supercomputer at the University of Illinois at Urbana-Champaign, the researchers expect X-rays emitted by a near-merger will be brighter and more variable than X-rays seen from single supermassive black holes. The pace of the changes links to both the orbital speed of gas located at the inner edge of the circumbinary disk as well as that of the merging black holes.
  • NASA's Fermi Links Cosmic Neutrino to Monster Black Hole
    2018.07.12
    For the first time ever, scientists using NASA’s Fermi Gamma-ray Space Telescope have found the source of a high-energy neutrino from outside our galaxy. This neutrino travelled 3.7 billion years at nearly light speed before being detected on Earth -- farther than any other neutrino we know the origin of. High-energy neutrinos are hard-to-catch particles that scientists think are created by the most powerful events in the cosmos, like galaxy mergers and material falling onto supermassive black holes. They travel a whisker shy of the speed of light and rarely interact with other matter, so they can travel unimpeded across billions of light-years. On Sept. 22, 2017, the IceCube Neutrino Observatory at the South Pole detected signs of a neutrino striking the Antarctic ice with an energy of about 300 trillion electron volts -- more than 45 times the energy achievable in the most powerful particle accelerator on Earth. This high energy strongly suggested that the neutrino had to be from beyond our solar system. Backtracking the path through IceCube indicated where in the sky the neutrino came from, and automated alerts notified astronomers around the globe to search this region for flares or outbursts that could be associated with the event. Data from Fermi’s Large Area Telescope revealed enhanced gamma-ray emission from a well-known active galaxy at the time the neutrino arrived. This active galaxy is a type called a blazar, where a supermassive black hole with millions to billions of times the Sun’s mass that blasts particle jets outward in opposite directions at nearly the speed of light. Blazars are especially bright and active because one of these jets happens to point almost directly toward Earth. Fermi showed that at the time of the neutrino detection, the blazar TXS 0506+056 was the most active it had been in a decade. The discovery is a giant leap forward in a growing field called multimessenger astronomy, where new cosmic signals like neutrinos and gravitational waves are definitively linked to sources that emit light.
  • Massive Black Hole Shreds Passing Star
    2015.10.21
    This artist’s rendering illustrates new findings about a star shredded by a black hole. When a star wanders too close to a black hole, intense tidal forces rip the star apart. In these events, called “tidal disruptions,” some of the stellar debris is flung outward at high speed while the rest falls toward the black hole. This causes a distinct X-ray flare that can last for a few years. NASA’s Chandra X-ray Observatory, Swift Gamma-ray Burst Explorer, and ESA/NASA’s XMM-Newton collected different pieces of this astronomical puzzle in a tidal disruption event called ASASSN-14li, which was found in an optical search by the All-Sky Automated Survey for Supernovae (ASAS-SN) in November 2014. The event occurred near a supermassive black hole estimated to weigh a few million times the mass of the sun in the center of PGC 043234, a galaxy that lies about 290 million light-years away. Astronomers hope to find more events like ASASSN-14li to test theoretical models about how black holes affect their environments.
  • X-ray Echoes Map a 'Killer' Black Hole
    2016.06.22
    Some 3.9 billion years ago in the heart of a distant galaxy, the tidal pull of a monster black hole shredded a star that wanderd too close. X-rays produced in this event first reached Earth on March 28, 2011, when they were detected by NASA's Swift satellite. Within days, scientists concluded that the outburst, now known as Swift J1644+57, represented both the tidal disruption of a star and the sudden flare-up of a previously inactive black hole. Now astronomers using archival observations from Swift, the European Space Agency's XMM-Newton observatory and the Japan-led Suzaku satellite have identified the reflections of X-ray flares erupting during the event. Led by Erin Kara, a postdoctoral researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland, College Park, the team has used these light echoes, or reverberations, to map the flow of gas near a newly awakened black hole for the first time. Swift J1644+57 is one of only three tidal disruptions that have produced high-energy X-rays, and to date it remains the only event caught at the peak of this emission. While astronomers don't yet understand what causes flares near the black hole, when one occurs they can detect its echo a couple of minutes later as its light washes over structures in the developing accretion disk. The technique, called X-ray reverberation mapping, has been used before to explore stable disks around black holes, but this is time it has been applied to a newly formed disk produced by a tidal disruption. Swift J1644+57's accretion disk was thicker, more turbulent and more chaotic than stable disks, which have had time to settle down into an orderly routine. One surprise is that high-energy X-rays arise from the innermost regions of the disk instead of a narrow jet of accelerated particles, as originally thought. The researchers estimate the black hole has a mass about a million times that of the sun. They expect future improvements in understanding and modeling accretion flows will allow them to measure the black hole's spin using this data.
  • NASA's RXTE Satellite Catches the Beat of a Midsize Black Hole
    2014.08.18
    Astronomers from the University of Maryland, College Park (UMCP) and NASA's Goddard Space Flight Center have uncovered rhythmic pulsations from a rare breed of black hole in archival data from NASA's Rossi X-ray Timing Explorer (RXTE) satellite. The signals provide compelling evidence that the object, known as M82 X-1, is one of only a few midsize black holes known. Dying stars form modest black holes measuring up to around 25 times the mass of our sun. At the opposite extreme, most large galaxies contain a supermassive black hole with a mass tens of thousands of times greater. Just as drivers traveling a highway packed with compact cars and monster trucks might start looking for sedans, astronomers are searching for a middle range of the black hole population and wondering why they see so few. M82 X-1 is the brightest X-ray source in Messier 82, a galaxy located about 12 million light-years away in the constellation Ursa Major. While astronomers have suspected the object of being a midsize, or intermediate-mass, black hole for at least a decade, estimates have varied from 20 to 1,000 solar masses, preventing a definitive classification. Working with Mushotzky and Strohmayer, UMCP graduate student Dheeraj Pasham sifted through about 800 RXTE observations of M82 in a search for specific types of brightness changes that would help pin down the mass of the X-ray source. As gas streams toward the black hole it piles up into a disk around it. Friction within the disk heats the gas to millions of degrees, which is hot enough to emit X-rays. Cyclical intensity variations in these X-rays reflect processes occurring within the disk. Scientists think the most rapid changes occur near the inner edge of the disk on the brink of the black hole's event horizon, the point beyond which nothing, not even light, can escape. With such close proximity to the black hole, the effects of Einstein's general relativity come into play, resulting in X-ray variations that repeat at nearly regular intervals. Astronomers call these signals quasi-periodic oscillations, or QPOs, and have shown that for black holes produced by stars, their frequencies scale up or down depending on the size of the black hole. When astronomers study X-ray fluctuations from many stellar-mass black holes, they see both slow and fast QPOs, but the fast ones often come in pairs with a specific 3:2 rhythmic relationship. For every three flashes from one member of the QPO pair, its partner flashes twice. The combined presence of slow QPOs and a faster pair in a 3:2 rhythm effectively sets a standard scale that gives scientists a powerful tool for establishing the masses of stellar black holes. A decade ago, Strohmayer and Mushotzky showed the presence of slow QPO signals from M82 X-1. In order to apply the tried-and-true relationship used for stellar-mass black holes, the researchers needed to identify a pair of steady fluctuations exhibiting the same 3:2 beat in RXTE observations. By analyzing six years of data, they located X-ray variations that reliably repeated about 3.3 and 5.1 times each second, just the 3:2 relationship they needed. This allowed them to calculate that M82 X-1 weighs about 400 solar masses — the most accurate determination to date for this object and one that clearly places it in the category of intermediate-mass black holes. Read the paper at http://www.nature.com/nature/journal/vaop/ncurrent/full/nature13710.html. Read the press release at http://www.nasa.gov/topics/universe/index.html.
  • Turning Black Holes into Dark Matter Labs
    2015.06.23
    A new computer simulation tracking dark matter particles in the extreme gravity of a black hole shows that strong, potentially observable gamma-ray light can be produced. Detecting this emission would provide astronomers with a new tool for understanding both black holes and the nature of dark matter, an elusive substance accounting for most of the mass of the universe that neither reflects, absorbs nor emits light. Jeremy Schnittman, an astrophysicist at NASA's Goddard Space Flight Center, developed a computer simulation to follow the orbits of hundreds of millions of dark matter particles, as well as the gamma rays produced when they collide, in the vicinity of a black hole. He found that some gamma rays escaped with energies far exceeding what had been previously regarded as theoretical limits. In the simulation, dark matter takes the form of Weakly Interacting Massive Particles, or WIMPS, now widely regarded as the leading candidate class. In this model, WIMPs that crash into other WIMPs mutually annihilate and convert into gamma rays, the most energetic form of light. But these collisions are extremely rare under normal circumstances. Over the past few years, theorists have turned to black holes as dark matter concentrators, where WIMPs can be forced together in a way that increases both the rate and energies of collisions. The concept is a variant of the Penrose process, first identified in 1969 by British astrophysicist Sir Roger Penrose as a mechanism for extracting energy from a spinning black hole. The faster it spins, the greater the potential energy gain. In this process, all of the action takes place outside the black hole's event horizon, the boundary beyond which nothing can escape, in a flattened region called the ergosphere. Within the ergosphere, the black hole's rotation drags space-time along with it and everything is forced to move in the same direction at nearly speed of light. This creates a natural laboratory more extreme than any possible on Earth. Previous work indicated that the maximum gamma-ray energy from the collisional version of the Penrose process was only about 1.3 times the rest mass of the annihilating particles. In addition, only a small portion of high-energy gamma rays managed to escape the ergosphere. These results suggested that a conclusive annihilation signal might never be seen from a supermassive black hole. However, earlier work made simplifying assumptions about the locations of the highest-energy collisions. Schnittman's model instead tracks the positions and properties of hundreds of millions of randomly distributed particles as they collide and annihilate near a black hole. The new model reveals processes that produce gamma rays with much higher energies, as well as a better likelihood of escape and detection, than ever thought possible. He identified previously unrecognized trajectories where collisions produce gamma rays with a peak energy 14 times the rest mass of the annihilating particles. The simulation tells astronomers that there is an astrophysically interesting signal they may be able to detect as gamma-ray telescopes improve.
  • Neutron Stars Rip Each Other Apart to Form Black Hole
    2014.05.13
    This supercomputer simulation shows one of the most violent events in the universe: a pair of neutron stars colliding, merging and forming a black hole. A neutron star is the compressed core left behind when a star born with between eight and 30 times the sun's mass explodes as a supernova. Neutron stars pack about 1.5 times the mass of the sun — equivalent to about half a million Earths — into a ball just 12 miles (20 km) across. As the simulation begins, we view an unequally matched pair of neutron stars weighing 1.4 and 1.7 solar masses. They are separated by only about 11 miles, slightly less distance than their own diameters. Redder colors show regions of progressively lower density. As the stars spiral toward each other, intense tides begin to deform them, possibly cracking their crusts. Neutron stars possess incredible density, but their surfaces are comparatively thin, with densities about a million times greater than gold. Their interiors crush matter to a much greater degree densities rise by 100 million times in their centers. To begin to imagine such mind-boggling densities, consider that a cubic centimeter of neutron star matter outweighs Mount Everest. By 7 milliseconds, tidal forces overwhelm and shatter the lesser star. Its superdense contents erupt into the system and curl a spiral arm of incredibly hot material. At 13 milliseconds, the more massive star has accumulated too much mass to support it against gravity and collapses, and a new black hole is born. The black hole's event horizon — its point of no return — is shown by the gray sphere. While most of the matter from both neutron stars will fall into the black hole, some of the less dense, faster moving matter manages to orbit around it, quickly forming a large and rapidly rotating torus. This torus extends for about 124 miles (200 km) and contains the equivalent of 1/5th the mass of our sun. The entire simulation covers only 20 milliseconds. Scientists think neutron star mergers like this produce short gamma-ray bursts (GRBs). Short GRBs last less than two seconds yet unleash as much energy as all the stars in our galaxy produce over one year. The rapidly fading afterglow of these explosions presents a challenge to astronomers. A key element in understanding GRBs is getting instruments on large ground-based telescopes to capture afterglows as soon as possible after the burst. The rapid notification and accurate positions provided by NASA's Swift mission creates a vibrant synergy with ground-based observatories that has led to dramatically improved understanding of GRBs, especially for short bursts.
  • NASA-led Study Explains How Black Holes Shine in Hard X-rays
    2013.06.14
    A new study by astronomers at NASA, Johns Hopkins University and the Rochester Institute of Technology confirms long-held suspicions about how stellar-mass black holes produce their highest-energy light.

    By analyzing a supercomputer simulation of gas flowing into a black hole, the team finds they can reproduce a range of important X-ray features long observed in active black holes. Jeremy Schnittman, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md., led the research.

    Black holes are the densest objects known. Stellar black holes form when massive stars run out of fuel and collapse, crushing up to 20 times the sun's mass into compact objects less than 75 miles (120 kilometers) wide.

    Gas falling toward a black hole initially orbits around it and then accumulates into a flattened disk. The gas stored in this disk gradually spirals inward and becomes greatly compressed and heated as it nears the center, ultimately reaching temperatures up to 20 million degrees Fahrenheit (12 million C), or some 2,000 times hotter than the sun's surface. It glows brightly in low-energy, or soft, X-rays.

    For more than 40 years, however, observations show that black holes also produce considerable amounts of "hard" X-rays, light with energy tens to hundreds of times greater than soft X-rays. This higher-energy light implies the presence of correspondingly hotter gas, with temperatures reaching billions of degrees.

    The new study involves a detailed computer simulation that simultaneously tracked the fluid, electrical and magnetic properties of the gas while also taking into account Einstein's theory of relativity. Using this data, the scientists developed tools to track how X-rays were emitted, absorbed, and scattered in and around the disk.

    The study demonstrates for the first time a direct connection between magnetic turbulence in the disk, the formation of a billion-degree corona above and below the disk, and the production of hard X-rays around an actively "feeding" black hole.

    Watch this video on YouTube.

  • Radio Telescopes Capture Best-Ever Snapshot of a Black Hole's Jets
    2011.05.20
    Centaurus A is a giant elliptical active galaxy 12 million light years away. Radio and X-ray images reveal features associated with jets emanating from near the galaxy's central supermassive black hole, which has a mass of 55 million suns. Now, the TANAMI project has provided the best-ever view of these jets. In the radio image of the galaxy's core, the black hole is invisible but the jets show in great detail. Features as small as 15 light-days across can be resolved. The powerful jets feed vast lobes of radio-emitting gas that reach far beyond the visible galaxy.
  • Simulations Uncover 'Flashy' Secrets of Merging Black Holes
    2012.09.27
    According to Einstein, whenever massive objects interact, they produce gravitational waves — distortions in the very fabric of space and time — that ripple outward across the universe at the speed of light. While astronomers have found indirect evidence of these disturbances, the waves have so far eluded direct detection. Ground-based observatories designed to find them are on the verge of achieving greater sensitivities, and many scientists think that this discovery is just a few years away.

    Catching gravitational waves from some of the strongest sources — colliding black holes with millions of times the sun's mass — will take a little longer. These waves undulate so slowly that they won't be detectable by ground-based facilities. Instead, scientists will need much larger space-based instruments, such as the proposed Laser Interferometer Space Antenna, which was endorsed as a high-priority future project by the astronomical community.

    A team that includes astrophysicists at NASA's Goddard Space Flight Center in Greenbelt, Md., is looking forward to that day by using computational models to explore the mergers of supersized black holes. Their most recent work investigates what kind of "flash" might be seen by telescopes when astronomers ultimately find gravitational signals from such an event.

    To explore the problem, a team led by Bruno Giacomazzo at the University of Colorado, Boulder, and including Baker developed computer simulations that for the first time show what happens in the magnetized gas (also called a plasma) in the last stages of a black hole merger.

    In the turbulent environment near the merging black holes, the magnetic field intensifies as it becomes twisted and compressed. The team suggests that running the simulation for additional orbits would result in even greater amplification.

    The most interesting outcome of the magnetic simulation is the development of a funnel-like structure — a cleared-out zone that extends up out of the accretion disk near the merged black hole.

    The most important aspect of the study is the brightness of the merger's flash. The team finds that the magnetic model produces beamed emission that is some 10,000 times brighter than those seen in previous studies, which took the simplifying step of ignoring plasma effects in the merging disks.

  • The Cloudy Cores of Active Galaxies
    2014.02.19
    At the hearts of most big galaxies, including our own Milky Way, there lurks a supermassive black hole weighing millions to billions of times the sun's mass. As gas falls toward a supermassive black hole, it gathers into a so-called accretion disk and becomes compressed and heated, ultimately emitting X-rays. The centers of some galaxies produce unusually powerful emission that exceeds the sun's energy output by billions of times. These are active galactic nuclei, or AGN.

    Using data from NASA's Rossi X-ray Timing Explorer (RXTE) satellite, an international team has uncovered a dozen instances where X-ray signals from active galaxies dimmed as a result of a cloud of gas moving across our line of sight. The new study triples the number of cloud events previously identified in the 16-year archive.

    The study is the first statistical survey of the environments around supermassive black holes and is the longest-running AGN-monitoring study yet performed in X-rays. Scientists determined various properties of the occulting clouds, which vary in size and shape but average 4 billion miles (6.5 billion km) across – greater than Pluto's distance from the sun — and twice the mass of Earth. They orbit a few light-weeks to a few light-years from the black hole.

  • Briefing Materials: NASA Missions Explore Record-Setting Cosmic Blast
    2013.11.21
    On Thursday, Nov. 21, 2013, NASA held a media teleconference to discuss new findings related to a brilliant gamma-ray burst detected on April 27.