Using the MIRI instrument onboard the James Webb Space Telescope, an international team of scientists made the first-ever detection of a mid-IR flare from Sagittarius A*, the supermassive blackhole at the heart of the Milky Way. In simultaneous radio observations, the team found a radio counterpart of the flare lagging behind in time. The paper is published on the arXiv preprint server.

Scientists have been actively observing Sagittarius A* (Sgr A)—a supermassive black hole roughly 4 million times the mass of the sun— since the early 1990s. Sgr A regularly exhibits flares that can be observed in multiple wavelengths, allowing scientists to see different views of the same flare and better understand how it emits light and how the emission is generated. Despite a long history of successful observations, and even imaging of the cosmic beast by the Event Horizon Telescope in 2022, one crucial piece of the puzzle— mid-infrared observations (Mid-IR)—was missing until now.

Infrared (IR) light is a type of electromagnetic radiation that has longer wavelengths than visible light, but shorter wavelengths than radio light. Mid-IR sits in the middle of the infrared spectrum, and allows astronomers to observe objects, like flares, that are often difficult to observe in other wavelengths due to impenetrable dust. Until the recent study, no team had yet successfully detected Sgr A*’s variability in the mid-IR, leaving a gap in scientists’ understanding of what causes flares, and questions about whether theoretical models are complete.

Researchers explored hydrogen forests and uncovered clues that may reveal hidden dark matter, potentially changing our understanding of the universe.

Some scientists think that dark energy could be a sort of defect in the fabric of the universe itself; defects like cosmic strings, which are hypothetical one-dimensional “wrinkles” thought to have formed in the early universe.

Some scientists think that dark energy isn’t something physical that we can discover. Rather, they think there could be an issue with general relativity and Einstein’s theory of gravity and how it works on the scale of the observable universe. Within this explanation, scientists think that it’s possible to modify our understanding of gravity in a way that explains observations of the universe made without the need for dark energy. Einstein actually proposed such an idea in 1919 called unimodular gravity, a modified version of general relativity that scientists today think wouldn’t require dark energy to make sense of the universe.

Dark energy is one of the great mysteries of the universe. For decades, scientists have theorized about our expanding universe. Now, for the first time ever, we have tools powerful enough to put these theories to the test and really investigate the big question: “what is dark energy?”