A taste of James Webb’s potential

How good will NASA’s new James Webb Space Telescope be? Good enough to uncover things never before seen by humanity, astronomers say.

Two studies led by Madeline Marshall from Australia’s ARC Centre of Excellence in All Sky Astrophysics in 3 Dimensions (ASTRO 3D) have found that the most powerful and complex space telescope ever built – due to launch late next year – will be able to reveal galaxies currently masked by powerful lights called quasars.

With colleagues from Australia, the US, China, Germany, and The Netherlands, Marshall first used the near-infrared capabilities of no less than NASA’s Hubble Space Telescope to study known quasars in hopes of spotting the surrounding glow of their host galaxies.

There were no significant detections to report, however, suggesting that dust within the galaxies is obscuring the light of their stars.

“Hubble simply doesn’t go far enough into the infrared to see the host galaxies. This is where Webb will really excel,” says Rogier Windhorst of Arizona State University, US, a co-author on the study, published in The Astrophysical Journal.

To determine what Webb is expected to see, the team then used a state-of-the-art computer simulation called BlueTides, developed by a team led by Tiziana Di Matteo from Carnegie Mellon University (CMU) in Pittsburgh, US.

“BlueTides is designed to study the formation and evolution of galaxies and quasars in the first billion years of the Universe’s history,” says CMU’s Yueying Ni, who ran the simulation. “Its large cosmic volume and high spatial resolution enables us to study those rare quasar hosts on a statistical basis.”

As described in a paper in the Monthly Notices of the Royal Astronomical Society, the team found that galaxies hosting quasars tended to be smaller than average, spanning only about 1/30 the diameter of the Milky Way despite containing almost as much mass as our galaxy.

“The host galaxies are surprisingly tiny compared to the average galaxy at that point in time,” says Marshall.

The galaxies in the simulation also tended to be forming stars rapidly, up to 600 times faster than the current star formation rate in the Milky Way.

The team then used these simulations to determine what Webb’s cameras would see if the observatory studied these distant systems.

They found that distinguishing the host galaxy from the quasar would be possible, although still challenging due to the galaxy’s small size on the sky.

“Webb will open up the opportunity to observe these very distant host galaxies for the first time,” says Marshall.

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