Scottish astronomers push James Webb deeper back in time


The Edinburgh Galaxy is the latest in a series of “furthest” observations from Webb

Scottish astronomers have spied what they believe is the most distant galaxy ever observed, using the new super space telescope, the James Webb.

The red spot is 35 billion light years away. We see it, as it were, only 235 million years after the Big Bang.

It is a preliminary, or “candidate”, result and will need a follow-up study for confirmation.

But for now, the team from the University of Edinburgh are celebrating and marveling at the power of James Webb.

“We’re using a telescope that was designed to do exactly this kind of thing, and it’s amazing,” said Callum Donnan, an astrophysics PhD student at the university’s Institute for Astronomy.

James Webb is the successor to the $10 billion Hubble Space Telescope and hunts for the first stars and galaxies to form in the 13.8-billion-year-old universe.

These objects are extremely faint, but the new observatory is specifically tuned to capture their glow in infrared light.

James Webb

James Webb

Edinburgh’s high profile will almost certainly be short-lived.

Since Webb began science operations in late June, astronomers have found increasingly distant candidates in images.

And if the designed performance is achieved, scientists could eventually see objects with Webb that existed perhaps as little as 100 million years after the Big Bang.

So we should expect a number of announcements in the weeks and months ahead.

The Edinburgh target is named CEERS-93316 and is said to have a redshift of 16.7.

Redshift is the term astronomers use when discussing distances in the cosmos.

It is a measure that describes the way light coming from an object has been “stretched” by the expansion of the universe to redder wavelengths.

The higher the redshift number assigned to a galaxy, the more distant it is and the earlier it is seen in cosmic history.

In recent days, a stream of increasingly large redshift numbers has been reported on the popular arxiv preprint server.

Maisie's Galaxy

Maisie’s Galaxy was found in a wide survey conducted by James Webb

The last 24 hours have been a good example of how quickly things can move.

The Edinburgh group derived their target from a broad survey of the sky that Webb is currently conducting called the Cosmic Evolution Early Release Science (CEERS) Survey.

The team actually running this survey released its own distant candidate on Monday, called CEERSJ141946.35+525632.8.

Named Maisie’s Galaxy after an astronomer’s daughter, this target has a redshift of 14.3, meaning it is seen about 280 million years after the Big Bang. Not as far as CEERS-93316, but still a remarkable prospect compared to the pre-James Webb era.

However, there is a big caveat to all of this. The early candidates announced from Webb observations have yet to undergo full spectroscopic investigation.

This process slices up the light coming from a galaxy to reveal its component colors – its spectra. These will provide the clearest picture of how light, which was originally emitted at visible wavelengths, has been stretched into the infrared over the course of cosmic history.

Only after this task is accomplished—and Webb has the instruments to do so—will distance requirements move on to a more secure footing

Graphics showing how James Webb is able to look back in time

Graphics showing how James Webb is able to look back in time

Another advantage of spectroscopy is that it will reveal the composition of objects.

The theory states that the very first stars were powered by only hydrogen, helium and a small amount of lithium – the elements created in the Big Bang.

Heavier atoms – astronomers call them all “metals” – had to be forged in these pioneer stars and their descendants.

“We can look at the colors of our galaxy in a broad sense, and it’s quite blue, suggesting a young stellar population. But it’s not blue enough for this galaxy to be made up of metal-free stars,” Donnan said.

It is Professor Steve Finkelstein, from the University of Texas in Austin, USA, who is the proud father of Maisie.

He will be a guest on Thursday’s Science In Action program on the BBC World Service.

“I had heard a quote for this telescope that it’s going to be transformative. And I said, ‘you know, it’s going to do a lot of really cool things, but will it really change the way we look at the universe? I couldn’t got more wrong. Textbooks are going to be rewritten on even just the data we got in the first week.”

Note on distances: The universe is expanding. During the time it takes the light from objects to reach us, these objects have receded a lot. Their positions today are therefore much, much further away than when the light was first sent out.

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