The source of the sky's X-ray glow

July 27, 2014

In findings that help astrophysicists understand our corner of the galaxy, an international research team has shown that the soft X-ray glow blanketing the sky comes from both inside and outside the solar system.

The source of this "diffuse X-ray background" has been debated for the past 50 years. Does it originate from the colliding with interplanetary gases within our ? Or is it born further away, in the "local hot bubble" of gas that a supernova is believed to have left in our galactic neighborhood about 10 million years ago?

The scientists found evidence that both mechanisms contribute, but the bulk of the X-rays come from the bubble. The solar wind, a stream of charged particles continuously emitted by the sun, appears to be responsible for at most 40 percent of the radiation, according to new findings published in the journal Nature.

"The overarching science goal of our work is to try to answer questions like: What does the local astrophysical environment look like? And what is the environment in which the sun was born?" said Susan Lepri, an associate professor of atmospheric, oceanic and space sciences in the University of Michigan College of Engineering.

"It's part of trying to understand our place in the universe."

Lepri, who studies the physics of the sun, provided key measurements of the solar wind and its charge states.

"This is a significant discovery," said Massimiliano Galeazzi, associate chair in the Department of Physics in the College of Arts and Sciences at the University of Miami and principal investigator of the study. "Specifically, the existence or nonexistence of the local bubble affects our understanding of the galaxy in the proximity to the sun and can be used as foundation for future models of the galaxy structure."

The findings confirm the existence of a local hot bubble, which had been previously debated.

The research team launched a research rocket into the upper atmosphere in 2012 to analyze the diffuse X-ray background. They focused on low-energy X-rays.

"At that low energy, the light gets absorbed by the neutral gas in our galaxy, so the fact that we observe it means that the source must be 'local,' possibly within a few hundred light-years from Earth," Galeazzi said.

"Until now it was unclear whether it comes from within the solar system (within few astronomical units from Earth), or a very hot bubble of gas in the solar neighborhood (hundreds of light-years from Earth)."

That's like trying to decide if a bright light in the sky is from an airplane or a star, Lepri said.

The next phase of the mission is scheduled to launch in December 2015. The research team also included scientists from NASA, the University of Wisconsin, the University of Kansas, Johns Hopkins University and CNES in France.

Explore further: NASA sounding rocket to study interplanetary medium

More information: The origin of the local 1/4-keV X-ray flux in both charge exchange and a hot bubble. Nature. DOI: 10.1038/nature13525

Related Stories

DXL: NASA launching X-ray emission mission

December 10, 2012

NASA will launch an astrophysics mission to study the Diffuse X-ray emission from the Local galaxy (DXL) December 9 from the White Sands Missile Range in New Mexico. The goal of this flight is to identify how much of that ...

Scientists reveal cosmic roadmap to galactic magnetic field

February 13, 2014

Scientists on NASA's Interstellar Boundary Explorer (IBEX) mission, including a team leader from the University of New Hampshire, report that recent, independent measurements have validated one of the mission's signature ...

Sun sends more 'tsunami waves' to Voyager 1

July 8, 2014

(Phys.org) —NASA's Voyager 1 spacecraft has experienced a new "tsunami wave" from the sun as it sails through interstellar space. Such waves are what led scientists to the conclusion, in the fall of 2013, that Voyager had ...

Recommended for you

New quasar discovered by astronomers

September 19, 2017

(Phys.org)—A team of astronomers led by Jacob M. Robertson of the Austin Peay State University in Clarksville, Tennessee has detected a new quasi-stellar object (QSO). They found the new quasar, designated SDSS J022155.26-064916.6, ...

The cosmic water trail uncovered by Herschel

September 19, 2017

During almost four years of observing the cosmos, the Herschel Space Observatory traced out the presence of water. With its unprecedented sensitivity and spectral resolution at key wavelengths, Herschel revealed this crucial ...

What do we need to know to mine an asteroid?

September 19, 2017

The mining of resources contained in asteroids, for use as propellant, building materials or in life-support systems, has the potential to revolutionise exploration of our Solar System. To make this concept a reality, we ...

A day in the life of NASA's Voyagers

September 19, 2017

At more than 10 billion miles away from Earth, there is no day and night. Time and space are fathomless and our Sun is a distant point of starlight—a faint reminder of the home NASA's twin Voyagers, humanity's farthest ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.