Astronomers released the clearest view yet of the supernova remnant Sgr A East near the Milky Way’s center. A team used a special technique to separate overlapping X-ray sources, creating a cleaner image. This work, published in The Astrophysical Journal, helps experts study elements like iron, sulfur, argon and calcium.

The center of the Milky Way galaxy is a chaotic place. In addition to the 4-million-solar-mass black hole known as Sagittarius A* (Sgr A*), the region is full of gas, dust, strong magnetic fields and stars in various stages of life—from birth to death.

Now, astronomers have released the clearest view yet of the remains of an exploded star that sits amid this cluttered galactic environment. The supernova remnant is named Sagittarius A East, or Sgr A East, and it is the closest to Sgr A* that astronomers know about.

Sgr A East emits light in many wavelengths, including X-rays that NASA's Chandra X-ray Observatory can see. Supernova remnants like Sgr A East give off X-rays because powerful shock waves rumble outward into space after the explosion and the stellar debris is superheated to millions of degrees.

Separating overlapping X-ray sources

In this packed galactic landscape, it is difficult to tease out what light is coming from the Sgr A East supernova remnant and what emanates from other objects. Astronomers have previously identified the primary contributors.

The two main sources of X-rays in this image, besides the supernova remnant itself, are colliding winds from a cluster of hot, massive stars and a diffuse, commingled glow from many fainter, overlapping X-ray sources. (This latter category is composed mainly of double-star systems including stars like our sun orbiting white dwarf stars.)

This new composite image of Sgr A East and the region around it contains X-rays from Chandra that are—for the first time—not contaminated by X-rays from other sources in this crowded field.

A team of astronomers used a special technique to separate the three main sources of X-rays and create this new, cleaner view of Sgr A East. This analysis also allowed the authors to make maps of the elements within the supernova remnant, including iron, sulfur, argon and calcium.

The work is published in The Astrophysical Journal.

A composite view across wavelengths

The new image of Sgr A East shows lower-energy X-rays detected by Chandra in green and high-energy ones in light blue, which appear purple in the middle of the supernova remnant. The researchers removed the pointlike sources of X-rays so they could study the diffuse emission in more detail.

The X-ray data have been combined with radio data from the NSF's Very Large Array in red and submillimeter-wavelength data from the James Clerk Maxwell Telescope in dark blue to complete this new composite view.

The bright radio emission surrounds X-rays from Sgr A East as well as the region around Sgr A*. The supermassive black hole is located at the center of the yellow spiral structure to the right of the purple X-rays from Sgr A East.

Shaping the black hole's surroundings

This new image will also allow scientists to examine how the winds from the stars in the nearby cluster have shaped the supernova remnant's evolution. This could help reveal the identity of the star that exploded to create Sgr A East and whether the supernova remnant has triggered outbursts from Sgr A* in the past.

Because Sgr A East is so close to Sgr A*, astronomers have long wondered if they influence one another. The authors' new work supports the idea that Sgr A East has played an active role in the black hole's environment by injecting energy into the region and keeping the gas surrounding Sgr A* hot and turbulent over the remnant's lifetime of about 10,000 years, although its exact age remains uncertain.

They have shown that Sgr A East has expanded into, compressed and heated the gas surrounding it, shaping its three-dimensional asymmetrical structure.