Scientists think that they’ve spotted a black hole’s gravity bending light emitted from the disk of matter around it right back toward the black hole, according to a new paper.
Black holes are extremely compact objects whose immense gravity warps space such that, beyond a point of no return called the event horizon, light can’t escape. We know that black holes can change the path that light travels, but this observation is the first known detection of its kind. Led by Riley Connors at CalTech, a team of scientists spotted light emitted from the disk of torn-up gas and dust surrounding a black hole bending back into it.
“We haven’t seen that before,” study author Victoria Grinberg from the University of Tübingen in Germany told Gizmodo. “We know it should happen. But prediction is one thing and actually seeing it is a different animal altogether.”
The researchers focused on a binary black hole system called XTE J1550-564, which has a mass around nine times that of the Sun and is approximately 14,350 light-years away. An X-ray telescope called the Rossi X-ray Timing Explorer (RXTE) first spotted the object in 1998, and the black hole has experienced several bright outbursts since then.
But this paper isn’t reliant on new observations. Instead, the scientists attempted to recreate the observations already recorded using various models. They focused on the x-ray spectra, particularly on x-ray light absorbed by iron atoms in the black hole’s disk. They found subtle features in the light’s properties that could only be explained if photons emitted by the matter in the disk were bending back from the effects of the black hole’s gravity, then being re-absorbed and re-irradiated by the disk. The team published their work recently in The Astrophysical Journal.
It’s a challenging scenario to model, Grinberg explained to Gizmodo. Not only does the team need to understand the complex physics around the disk, combining atomic physics and general relativity, but they also need to fully understand all of the quirks of the RXTE telescope.
This is an early step, and as the adage goes, all models are wrong, but some are useful. Every scientist-built model relies on inherent assumptions that may lead to different results than what’s actually happening. The team behind this new model is aware of that, and they are working to further develop their model in order to include more details. Perhaps even more importantly, they must identify more objects like XTE J1550-564 and re-run their analysis.
But if the work holds, it would be an amazing discovery: concrete proof that what we’ve always thought happens around black holes is truly occurring.