In a significant development, the Event Horizon Telescope (EHT) has observed a powerful and unexpected flare from the supermassive black hole M87*, located at the center of the galaxy M87, approximately 55 million light-years from Earth. This flare, lasting around three days in April and May 2018, represents the first such event recorded since 2010 and is notably more energetic than typical emissions from M87*.
The EHT, a global network of 25 ground-based and orbital telescopes, detected the flare as high-energy gamma rays. M87* has an estimated mass of about 5.4 billion solar masses, significantly larger than Sagittarius A*, the supermassive black hole at the center of our Milky Way, which has a mass of approximately 4.3 million solar masses.
Unlike Sagittarius A*, which resides in a relatively empty region of space, M87* is actively consuming surrounding material, leading to the formation of high-energy jets associated with the flare. Giacomo Principe, project leader and researcher from the University of Trieste, stated, 'The data collected from EHT's sub-millimeter observations provide a unique opportunity to understand the nature of gamma-ray emission regions and their potential connection to changes in the M87 jet.'
The observations reveal that M87* is surrounded by an accretion disk and hot gas, or plasma, which spins around the black hole before being consumed. Strong magnetic fields channel material from the accretion disk to the black hole's poles, accelerating particles to near-light speeds and ejecting them as high-energy jets.
These jets extend tens of millions of times wider than the black hole itself, illustrating the vast scale of this cosmic phenomenon. The precise mechanism by which black holes launch these jets remains an open question, and EHT scientists hope this flare event will provide insights into the origins of cosmic rays detected on Earth.
In addition to EHT, other instruments, including Fermi, NuSTAR, Chandra, and Swift, contributed to this coordinated observation campaign. Elisabetta Cavazzuti, head of Fermi, noted significant increases in gamma-ray emissions during the flare, underscoring the importance of multi-wavelength observations.
Researchers have also observed changes in the jet angle and related variations at the event horizon, suggesting a connection between the black hole's boundary and its powerful jets. Principe remarked on the asymmetry of the ring observed during the campaign, highlighting the dynamic nature of black hole emissions.