The James Webb Space Telescope's early galaxy images were oddly bright. Now we know why

[Admin]

Distant galaxies that existed a few hundred million years after the Big Bang are brighter than expected in JWST images because they were experiencing bursts of intense star formation.

The James Webb Space Telescope's early galaxy images were oddly bright. Now we know why : Read more

 

[Helio]

I could be wrong, but this might be a ‘I told you so.”

The earliest stars were Texas stars — big and bright.

 

[rod]

Very interesting, everything okay now in the BB model for high redshift galaxies seen by JWST, it seems

https://arxiv.org/abs/2307.15305 and the 13-page report on the simulations makes for good reading.

"...Using approximately 25,000 galaxy snapshots at 8≤z≤12 in a suite of FIRE-2 cosmological "zoom-in'' simulations from the Feedback in Realistic Environments (FIRE) project, we show that the observed abundance of UV-bright galaxies at cosmic dawn is reproduced in these simulations with a multi-channel implementation of standard stellar feedback processes, without any fine-tuning."

Okay, the paper states this situation about Population III stars.

"4. DISCUSSION AND CONCLUSIONS We have demonstrated that the FIRE-2 simulations
with a multi-channel implementation of standard stellar feedback processes can reproduce well the observed
abundance of UV-bright galaxies at z ≳ 10, including both the photometrically selected candidates and the
spectroscopically confirmed sources recently discovered by JWST. We further showed that the bursty SFH predicted to be common in galaxies at cosmic dawn is important for explaining the bright-end of the UVLF. With
burstiness included, the simulations demonstrate that a boosted UV emissivity due to, e.g., an enhanced SFE,
a top-heavy IMF, AGN contributions, or Population III stars (see e.g., Harikane et al. 2023b,c), is not necessary
to explain the bright-end UVLF at z ≳ 10."

The new simulation does not confirm Population III stars in the universe or use them.

 

[Helio]

It also helps to recall that with hotter stars comes not only greater UV but greater luminosity. I once assumed the peak wavelength made a key difference, but as the peak moves so to does the total luminosity, just as a growing tide lifts all.... waves.

 

[Unclear Engineer]

We're going to need a bigger telescope!

It is no surprise to me that the model of star and galaxy formation can be tweeked to fit whatever the new observations are. There are so many unconstrained variables that it would be very hard to find something that could not be fit with a simulation.

It would be a lot more convincing if they predicted what they found, instead of being surprised and then finding an explanation.

It would be a lot more convincing if they could show that, before some point in time, there were no stars or galaxies.

But, to do that, to see all the way back to before cosmic dawn, they are going to need a bigger telescope!

 

[Helio]

We're going to need a bigger telescope!

Always! The Magellan and other monsters are coming.

It is no surprise to me that the model of star and galaxy formation can be tweeked to fit whatever the new observations are. There are so many unconstrained variables that it would be very hard to find something that could not be fit with a simulation.

Though I had guessed this would happen, notice that astronomers waited until they had the data to support their position. Perhaps more data will reveal something new. Given the technology and data quality, if there is something new lurking, you can bet they will be happy to find it. But, till then, BBT is looking ok, IMO.

It would be a lot more convincing if they predicted what they found, instead of being surprised and then finding an explanation.

I suspect the excitement of something new made the headlines. It's a safe bet that they most knew the Pop III stars are brighter, so galaxies would naturally be brighter. I do think that they are still a little surprised to see more galactic structure for their early age, but the range of age I've read in the past suggests that this is well within their full range of possible formation.

It would be a lot more convincing if they could show that, before some point in time, there were no stars or galaxies.

That's a tall order given that astronomers like to have at least a few photons to work with.

 

[billslugg]

If galaxies had existed at 380,000 years after BB, when CMBR originated, we would probably be able to see them in the CMBR anisotropy. After all, Andromeda spans six full Moons. WMAP resolution 13 arc-minutes.

 

[Helio]

If galaxies had existed at 380,000 years after BB, when CMBR originated, we would probably be able to see them in the CMBR anisotropy. After all, Andromeda spans six full Moons. WMAP resolution 13 arc-minutes.

Yes. I haven't been that interested in keeping track on the earliest times some think the data is suggesting for galaxy formation, but I would expect them to be 200 Myrs or more. 200 Myrs would indeed be on the very early edge of estimates that I think I've stumbled across over the last few years, making it a "surprise", but hardly shocking.

But even 200 Myrs is over 500x longer than it took for atoms to first combine (Recombination) to form the CMBR.

DM likely is playing an even bigger role in assisting galaxy formation, which again, shouldn't be shocking since we know so little about it. Perhaps quantum behavior has a slightly greater effect on DM "particles" to enhance the anisotropy necessary to see the universe with enough density for galaxy formations, and perhaps stars as well.