Super Massive Black Holes and Binary Stars

Supermassive black holes, packing millions to billions of suns, are fundamentally invisible because nothing—not even light—can escape their gravitational pull. To detect them, astronomers look for their dramatic effects on the surrounding environment: superheated accretion disks emitting blinding X-rays, the bending of light, and the erratic, high-speed orbits of nearby stars.Unveiling the Invisible GiantsThe European Southern Observatory (ESO) has been instrumental in utilizing state-of-the-art instruments, like the GRAVITY instrument on the Very Large Telescope Interferometer (VLTI), to track the frantic orbits of stars at the center of the Milky Way. These stellar motions provided the definitive proof that an invisible, dormant black hole (Sagittarius A) with a mass of about 4 million Suns resides in our galactic core.Visualizing the ShadowBecause direct imaging was long thought impossible, the global Event Horizon Telescope (EHT) collaboration changed the landscape by capturing the first-ever images of supermassive black holes. By linking radio telescopes across the globe, they successfully photographed the glowing ring of gas and the distinct dark shadow of the supermassive black hole at the center of the Messier 87 (M87) galaxy, as well as our own Sagittarius A.Active vs. DormantNot all of these cosmic behemoths remain quiet. In "active" galaxies, quasars, and blazars, the supermassive black hole is surrounded by a violently churning accretion disk. The intense magnetic fields and extreme gravity cause streams of matter to be ejected into space at nearly the speed of light, producing high-energy radiation that spans across the electromagnetic spectrum.