Issue with LCDM distance

[RichardRavenhall]

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Webb observes a luminosity distance in conflict with LCDM distance prediction.

 

Per the 6/6/23 paper “JADES. Possible Population III signatures at z=10.6 in the halo of GN-z11”, R. Maiolino et al, there is a high probability that LCDM predicted galaxy distances are inconsistent with Webb findings.  This is due to recent Webb observations of an exceptionally high luminosity galaxy in close alignment (and at z = 10.603) to the super bright galaxy GN-z11 (at z = 10.957).  Webb finds an ~ 20 Gly luminosity distance that is approximately 35% to 40% lower than the 32 Gly predicted by LCDM. 

 

The following is a copy of the paper’s introducing the information: https://arxiv.org/pdf/2306.00953.pdf

“Here we present NIRSpec-IFU and NIRSpec-MSA observations of the region around GN-z11, an exceptionally luminous galaxy at z=10.6, which reveal a >5σ detection of a feature consistent with being HeII λ1640 emission at the redshift of GN-z11. The very high equivalent width of the putative HeII emission in this clump (170 A), and the lack of metal lines, can be explained in terms of photoionisation by PopIII stars, while photoionisation by PopII stars is inconsistent with the data. It would also indicate that the putative PopIII stars likely have a top-heavy initial mass function (IMF), with an upper cutoff reaching at least 500 M⊙. The PopIII bolometric luminosity inferred from the HeII line would be ∼2×1010L⊙, which (with a top-heavy IMF) would imply a total stellar mass formed in the burst of ∼6×105M⊙.”  Cited in: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO).

 

Mainstream cosmology assumes the correctness of LCDM distances by verifying them via the “Cosmology Distance Ladder”.  There are many who challenge the ladder’s viability, though this measurement framework has yet to be proven “correct” or “incorrect”.  Yet, the extremely improved accuracy of Webb’s data may provide new physics.  Thus, the difference between these two approaches could have major significance.

[RedshiftDrift]

@RichardRavenhall you write

exceptionally high luminosity galaxy in close alignment (and at z = 10.603) to the super bright galaxy GN-z11 (at z = 10.957)

However, the paper only mentions one galaxy, GN-z11, at redshift z=10.603. (The foreground galaxy at $z\approx 2$ does not contribute to the HeII spectrum.) On p. 4:

The 2D spectrum shows a tentative signal at 1.905 μm, which consistent with the expected location of HeIIλ1640 at the redshift of GN-z11 (z=10.603), peaking at about 0.5′′ from GN-z11.

The "clump" is not another galaxy but "HeII detection in the halo of GN-z11", as explicitly written in $\S3.1$. The paper does not report a distance, but the spectrum of the ionized halo of GN-z10.

P.S. For papers on arXiv it is desirable to give the link to the abstract https://arxiv.org/abs/2306.00953, never to the pdf version of the article.

[khuramonline]

Circular Logic vs circular logic.

"There is difference between LCDM distance and Luminosity based distance" "noted" by JWST.

As if this "Luminosity based distance" does not include LCDM based formulas.

[RichardRavenhall]

Luminosity based distance in this case has significance because it doesn't include LCDM formulas.

[RichardRavenhall]

I back off my above reply. Do we have anybody that is knowledgeable about the subject?

[khuramonline]

I back off my above reply. Do we have anybody that is knowledgeable about the subject?

Luckily I just recently had a conversation about exact same topic i.e. "Luminosity based distance of GNz-11" with Chat-GPT. Conversation date was 24-05-2023.

At first GPT did surprise me by stating that Luminosity distances are also based on Cosmological Model used.

The conversation proceeded. After few other questions, then I asked following question about pure D_L (Luminosity distance) of GNz-11:

Here I was not satisfied by the answer. The conversation proceeded. After few other questions, then I asked following question:

The conversation proceeded. After another question, I asked following question:

In further conversation, the GPT provided the value of 282 ... That was ambiguous value because GPT avoided to confirm or exactly tell that it is distance in billion light years.

Anyways, my original stance stands.

Another thing I want to say is that Luminosity is pure empirical thing. Luminosity based OFFICIAL distance cannot be in terms of Comoving distance of 20 BLY or 32 BLYs.

What is Empirical is ONLY the light travel distance. Luminosity of only the light travel distance can be noted.

If they have told us luminosity distance in terms of comoving distance then obviously they have employed CIRCULAR logic. They DO HAVE CONTAMINATED the luminosity distances with LCDM based formulas.

[RichardRavenhall]

Things come down to different interpretations and I offer what could be a different perspective and possible new information. The clump is assumed to be a small galaxy at z = 10.603 near Gn-z11 which we know has a z = 10.957.

The paper describes work that is looking for PopIII stars, not distances. It presents Webb observations of the region around GN-z11 and finds an exceptionally luminous galaxy at z=10.6. It also indicates an associated luminosity distance of ∼2×1010 L⊙ or ~20 Gly.

There can only be one correct distance. Is it ~20 Gly as inferred from Webb observations, 32 Gly as stipulated by LCDM, or completely different?

Note that the ~20E9 number only appears in the paper’s abstract and is not addressed again. Could this have significance?

[RedshiftDrift]

See the updated value for the redshift of GN-z11, z=10.60, see arXiv:2302.07234.

Gn-z11 which we know has a z = 10.957

No, the incorrect value 10.957 reported in an article published in 2021¹ is based on a "probable detection of three ultraviolet emission lines" which turned out to be wrong.

The galaxy GN-z11 and the halo (clump) are all part of the same structure at z = 10.603, there is nothing at z=10.957.

Footnotes

1. Incorrect value published in Nature Astronomy volume 5, pages 256–261 (2021) ↩

[RichardRavenhall]

Wow - so GN-z11's z is not 10.957. This could mean that all galaxy z's are not as precisely known as we believed. Does mainstream cosmology agree with this finding?

[RedshiftDrift]

This is common practice, the papers arXiv:2302.07234 and arXiv:2306.00953 report GN-z11 at z=10.60 but there is still a small risk of error.

These numbers are never set in stone. The 2021 paper mentioned a "probable detection" to indicate that the spectroscopic lines may not be identified correctly. Looking at the spectrum, the signal-to-noise was not that great, so it's not surprising they picked the wrong lines. And when the redshift is only photometric (like most of JWST galaxies), the galaxies are said to be high-redshift candidates! The published values of z are accurate to 10% unless there is an interpretation error, in which case the value of z can be off by a factor of three!
Every astronomer accepts that.

galaxy z's are not as precisely known as we believed.

One has to read between the lines, every measurement is at risk of an incorrect interpretation.

[RichardRavenhall]

I appreciate both of your replies but suspect that none of us has changed anybody else's original views. Hopefully the over 20 billion spent on Webb will help us find a better answer.