The Science Behind Our Images and Videos

The next generation Event Horizon Telescope (ngEHT) will transform our understanding of black holes.  It will improve on the state-of-the-art technology of the original Event Horizon Telescope (EHT), which produced the first-ever image of a black hole. The ngEHT will capture better black hole images—and even movies—than ever before. These revolutionary images and videos will further one of the greatest scientific achievements of the century, shedding light on some of the most fundamental questions of our universe.

Testing Einstein’s Theory of General Relativity

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Image Credit: ESO, ESA/Hubble, M. Kornmesser/N. Bartmann

Under the watchful eye of the next generation Event Horizon Telescope, Einstein’s Theory of General Relativity will face one of its greatest challenges yet. Supermassive black holes are found at the centers of galaxies. They have the strongest gravitational force in the universe. Nothing, not even light, can escape their pull once it crosses the point of no return, called the event horizon. This gravity warps the very fabric of spacetime into a singularity, an infinitely dense point at the center where all the mass is located. Because they are such extreme objects, black holes act as the perfect laboratories to put Einstein’s theory to the test. 

With high-resolution black hole images and videos, the ngEHT will detail the size, shape, and variability of the accretion disk, the glowing hot ring of gas that surrounds black holes. It will further explore the stream of outflowing particles that mysteriously accelerate away from the black hole. These observations will test the predictions of General Relativity. 

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Accretion and photon ring layers. Image Credit: George Wong and Michael Johnson

Photon ring and spin. Video Credit: Michael Johnson and Ziri Younsi

Because black holes curve spacetime itself, rays of light bend as they pass near it, forming arcs and even rings. The ngEHT will elucidate the photon ring: the thin loops of light that orbit just outside the black hole. The ngEHT will even provide insight into advanced astrophysical concepts like the black hole’s spin, the Kerr metric, and the no-hair theorem. Scientists will compare each of these findings to their predictions to see if Einstein’s theory holds up in the most extreme environment in the universe.

Mapping Magnetic Fields Near the Horizon

Just one magnet, small enough to fit in your hand, can produce a magnetic force powerful enough to resist the entire Earth’s gravity. Despite its power, the magnetic field can be devilishly tricky to measure in space. Scientists suspect the magnetic field plays a crucial role in shaping a black hole’s accretion disk (the hot cloud of gas orbiting the black hole) and relativistic jets (the fountain of particles often rushing at near-light speed away from the black hole). However, scientists have struggled to map the structure of the magnetic field surrounding a black hole.

Video Credit: Hotaka Shiokawa

Using clues found in polarized light, the EHT has begun to uncover how the magnetic field shapes black holes through the first polarized image of a black hole ever. The ngEHT will take this research to the next level. These discoveries may finally expose secrets about the accretion disk, such as its electron density and temperature, and the powerful relativistic jets. Scientists will at last be able to answer some of the most important mysteries surrounding these voracious black enigmas. 

Video Credit: Smithsonian Astrophysical Observatory and Crazybridge Studios

Discovering the Origin of Black Hole Jets

One of the most remarkable features of black holes are their relativistic jets. Despite a black hole’s almost unfathomable power to suck in matter, particles at its north and south poles can slingshot away from the black hole at near-light speeds. Scientists suspect the magnetic field plays a primary role in this bizarre phenomenon, but it will take a telescope with the power of the ngEHT to confirm this hypothesis. 

Video Credit: Koushik Chatterjee

With a variety of new observational techniques, the next generation Event Horizon Telescope will capture videos that reveal how black hole jets form, collimate (get focused into a thin beam), and accelerate. These videos may show that relativistic jets are key factors driving the evolution of galaxies. Findings like these would connect science at the horizon scale with science at the galactic scale, opening new windows into the study of black holes, galaxies, and even the universe itself.

Video Credit: EHT Multiwavelength Working Group, EHT Collaboration, EAVN, H.E.S.S., MAGIC and VERITAS; EVN; VLBA; GMVA; HST; Swift; Chandra; NuSTAR; Fermi; NASA, ESA and ESO