JWST confirms: no difference

[Jacob Navia]

[[Mod. note -- This article arrived at my mailbox with some characters
in the quotation garbled. I have corrected and LaTeX-ifiedthe garbled
characters by referring to the paper on arXiv. -- jt]]

In my previous message I predicted that JWST will se no difference between
the galaxies at 13.5 billion years and much closer glaxies.

A tentative confirmation appeared in one of the first papers I could get
about the deep field image published by NASA.

The article is arXiv:2207.09434v1 [astro-ph.GA] 19 Jul 2022,Two Remarkably
Luminous Galaxy Candidates at z =approxapprox 11 - 13 Revealed by JWST

They say in page 8 of their paper:

In Figure 5, we compare this estimate with previous UV LF determinations
and with extrapolations from lower redshifts. In particular, we show that
an extrapolation of the Schechter function trends estimated at $z = 3--10$
results in an LF at $M_\text{UV} = 21$ that is a factor $>10 \times$ lower
than our estimate. Interestingly, however, when extrapolating the trends
in the double-power law LFs from Bowler et al. (2020) to $z \tilde 11.5$
(the mean redshift of our sources), we find relatively good agreement.
In fact, GN-z11 also lies on this extrapolated LF. However, this would
indicate very little evolution in the bright galaxy population at $z > 8$.
Indeed, our estimate is in good agreement with previous z \tilde 10$ UV LF
determinations and constraints at the bright end from Oesch et al. (2018);
Bouwens et al. (2019); Stefanon et al.

If I understand that correctly the new much older galaxies extrapolate
nicely from values in lower z regime.

NO BREAK, we are seeing the same. Note also that the GMz13 galaxy looks
circular, i.e. could be a spiral galaxy... All this is at z=13, i.e. at
only 332 million years after the supposed "bang"...

In the abstract the author explicitly say:

They extend evidence from lower redshifts for little or no evolution in the
bright end of the UV luminosity function into the cosmic dawn epoch, with
implications for just how early these galaxies began forming

The mass of those galaxies is 10^9 solar masses. Since in the first 50
million years the universe should have been too hot to form stars, the
billion solar masses were created in only 280 million years!!!

Out of a perfectly smooth big bang (see the CMB that is quite smooth)...

This is a tentative confirmation. Let's keep cool, and wait for more
results.

[[Mod. note -- You say "NO BREAKS", but the paper's abstract states in
part

> Our most secure candidates are two $M_\text{UV} \approx -21$ systems:
> GLASS-z13 and GLASS-z11. These galaxies display abrupt $\gtsim 2.5$ mag
> breaks in their spectral energy distributions, consistent with complete
> absorption of flux bluewards of Lyman-$\alpha$ that is redshifted to
> $z \approx 13$ and $z \approx 11$.

By "breaks" the authors mean that their galaxy-candidates' "spectra"
(really just comparison of brightness at different wavelengths) show
sharp drops blueward of some wavelength (about 1.6 micrometers observed
wavelength according to figure 1). The authors attribute this to shorter
wavelengths being shorter than the Lyman-alpha wavelength (about 121 nm);
such wavelengths are strongly absorbed by hydrogen gas (e.g., in the
intergalactic medium near the galaxies).

This usage of "break" is pretty common in high-redshift galaxy studies.
-- jt]]