Astronomers accidentally discover 'dark' primordial galaxy with no visible stars

Jan 13, 2024
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DI'd the astronomers forget humans only see approximately 1% of the visible light spectrum no matter how the subject is enhanced to make it visible?
Nice find!

Also remarkable about J0613+52 is the fact that it appears to be turning just like a normal spiral galaxy would.

That seems to agree with new ideas on galaxy formation triggered by the observation of early spirals and even bars ["Ripples in the oldest known spiral galaxy may shed light on the origins of our Milky Way", Space, By Samantha Mathewson published January 03, 2024; “Detecting a disc bending wave in a barred-spiral galaxy at redshift 4.4.”, Tsukui et al., Monthly Notices of the Royal Astronomical Society, Volume 527, Issue 3, January 2024]. The paper has notes on potential gas disks.

“The dominant gas disc, by itself gravitationally unstable, potentially leads to the formation of a gas bar (Barnes & Tohline 2001), as an axisymmetric 100 per cent gas disc is theoretically proven to form a self-gravitating stable gaseous bar structure (Cazes & Tohline 2000).”

The latter reference discuss gravitational convective and vorticity models and find the early spiral observed bending mode, with the convective “polytrope n=3/2” model recognizable as models for stars, star cores and gas planets [“Polytrope”, Wikipedia]. The “polytropic process” is a process of systems with energy transfers such as gas convection, so a stable dark and baryon matter gas only galaxy, and its rotation, seems eminently possible!
DI'd the astronomers forget humans only see approximately 1% of the visible light spectrum no matter how the subject is enhanced to make it visible?
Why would they forget!? And why is that relevant for looking for readily visible stars?

Too transparent, the amount of matter is clearly negligible compared to a real galaxy. So, it is not, and certainly will never be, a galaxy at all.
If astronomers define it as an LSB galaxy object instead of a gas cloud, why would anyone protest?

Assuming the galaxy was part of the survey, the arxiv paper on the survey itself [] defines such a galaxy by its H I hydrogen line luminosity mass. It must be bright enough not to be confused with a regular but more diffuse gas cloud of the intergalactic medium:

In principle, massive, or giant, LSB galaxies can be defined on different criteria. Based on surface photometry, Sprayberry et al. (1995) defined a “diffuseness index” to distinguish massive LSB galaxies, which is based on the deprojected blue central surface brightness µB(0) and the scale length of the disk hr – the 7 giants in their paper have⟨µB⟩ = 23.2 mag arcsec−2 and ⟨hr⟩ = 13.0 kpc. Other selection criteria can be used as well, such as: deprojected central blue disk surface brightness µB(0)≥ 23 mag arcsec−2 and H i mass MHI≥10^9.5−10 M⊙ or optical diameter≥50 kpc (e.g. Kulier et al. 2020; Mishra et al. 2017; Pickering et al. 1997). In the present study we use the criterion MHI≥10^10 M⊙ to identify massive galaxies, although we also consider the cases with high dynamical mass as defined by an inclination-corrected line width W50,cor ≥ 500 km s−1.
Hence their criteria is not only expert but not subjective. Your personal criteria seem to fail on both these points to satisfy the demands of the expert community as they do galaxy science. It may be that the "massive" mass criteria failed this galaxy, but they discuss mass trends in the original LSB sample. "There are no obvious trends between the various measured global galaxy properties, particularly between mean surface brightness and galaxy mass."

See also my own response to the article, where I relate science of gas cloud galaxies being predicted by models which also may have implications for early galaxy formation.
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Jan 28, 2023
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I have some reservations about the quality of scholarly expertise lately. As is typical, they have been tromping around for more than a century with various hypotheses about general relativity and the other several dozen works of Albert Einstein and are constantly surprised by "discoveries" that they should have thought were ahead of them. And then, it's usually made clear that "their discoveries" were already reported by their predecessors in the good old 20th century, so these 2-3 new generations of scientists have discovered...nothing.

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