An astronomer has stitched together hundreds of images of the center of our galaxy, the Milky Way, to create a stunning new panorama of this busy and important region of space. It also reveals new insights about mysterious phenomena occurring at the heart of our slice of space.
Crafted by Q. Daniel Wang, a professor of astronomy at the University of Massachusetts Amherst, the unprecedented visuals capture some of the enigmatic processes that occur at the galactic core. In addition to shedding light on the weird environment at the center of our own galaxy, the results also have implications for the formation and evolution of galaxies across the universe.
The Milky Way’s core is hard to observe in visible light due to the vast amounts of dust and gas surrounding its supermassive black hole, Sagittarius A* (Sgr A*). To penetrate through this haze, Wang used X-rays and radio observations from NASA’s Chandra X-ray Observatory and South Africa’s MeerKAT telescope to probe the region’s mysterious magnetic threads and enormous plumes of hot gas, according to a recent study published in the Monthly Notices of the Royal Astronomical Society.
“Central regions of galaxies are believed to play an essential role in galaxy formation and evolution, although how this actually works remains greatly uncertain,” Wang said in an email. “Because of its proximity, the central region of our galaxy around the supermassive black hole Sgr A* is a unique laboratory to conduct a high resolution study in an extreme environment that resembles those in other galactic nuclei.”
Wang’s history with Chandra stretches back some 20 years, as he served as the principal investigator of the observatory’s first large-scale X-ray survey of the galactic center. Those initial observations are included in the new composite, along with newer images from the space telescope, which was launched into orbit in 1999 and is still operating today.
The panorama is composed of 370 telescope views that expose many galactic features above and below the core (you can switch between various wavelength filters at this link). Of particular interest is a newly identified X-ray-emitting thread, known as G0.17-0.41, which stretches across about 20 light years and is likely the product of a combustible event known as a magnetic reconnection.
These reconnections occur when magnetic field lines that are oriented in opposite directions crash into each other and rapidly twist together, releasing colossal amounts of energy. Astrophysicists have thoroughly observed such reconnections closer to home, within our Sun: magnetic field lines that link within our star produce flares, coronal mass ejections, and other violent stellar phenomena.
Scientists think analogous versions of these solar reconnections also occur throughout interstellar space, though their mechanisms and effects are generally not well-observed. Fortunately, the strong magnetic field at our galaxy’s center offers a rare opportunity to glimpse them in action.
Wang imaged G0.17-0.41 in both X-ray and radio light, and found that it appears to be associated with a large plume of hot gas that might be helping to fuel the explosive event. In turn, magnetic reconnections are likely contributing to the formation of large-scale gas structures that extend from the galactic center into its halo, a lead that Wang plans to follow up on in his future research.
“I’d like to confirm that magnetic reconnections are indeed responsible for many of the X-ray threads and radio filaments observed in the region and to see how effective magnetic fields are transporting the energy from the center to large-scale structures,” where it is released, he said.
As to the most recent study, Wang remains “humbled” but “not surprised” by the breathtaking new visuals of what he calls the “downtown” of our galaxy, as revealed in his study and composite panorama.
“We know that the Galaxy is a complex ecosystem,” Wang concluded. “It will be a long way to truly understand how it works.”