Revisiting the Big Bang: Galaxy HUDF-JD2

[roland]

After the discovery of galaxy HUDF-JD2 is the big bang theory to be revised?

 

[Garth]

Hi roland, and welcome to these Forums!
You didn't have to submit your thread twice! I expect you know that and only hit the 'submit' button twice by mistake.

After the discovery of galaxy HUDF-JD2 is the big bang theory to be revised?

This has been discussed before here: Is there an Age Problem in the Mainstream Model?. In that thread I said (refering to HUDF-JD2):

but it is instructive to realize that already we have to reconcile the present observations by either modifying our stellar nucleosynthesis model or the cosmological model.

Does that answer your question?

Garth

 

[Nereid]

There's also the question "how certain are we of the distance and nature of this spot of fuzz?"

For starters, despite many hours with a VLT, a Keck, and a Gemini, no spectrum was detected (so the distance estimate remains a photometric one, and galaxy SED modeling not at all well constrained).

For seconds, if it is so young, who's to say that galaxy evolution models are particularly accurate? (I realize you can reverse the logic, but you still have just one data point).

And last (for now), is anyone brave enough to be confident about the selection effects?

Rumours of the danger posed by HUDF-JD2 to consensus cosmology models are greatly exaggerated.

 

[roland]

Rumours of the danger posed by HUDF-JD2 may be the tip of the iceberg. We must await the launch and deployment of JWST. However I shall never cease to be ammused. Merci Garth.

 

[Garth]

Rumours of the danger posed by HUDF-JD2 to consensus cosmology models are greatly exaggerated.

But we also have high-z quasars with significant iron abundances, and iron is the last element to be formed in fusion processes. In particular there is: APM 08279+5255at z = 3.91 whose age is 2.1 Gyr when the universe was only 1.6 Gyrs old (according to LCDM model expansion).

This age estimate is consistent with http://www.ingentaconnect.com/content/bsc/mnr/2003/00000340/00000004/art00002 Alcaniz J.S.; Lima J.A.S.; Cunha J.V, Monthly Notices of the Royal Astronomical Society, Volume 340, Number 4, April 2003, pp. L39-L42(1)

But these age estimates are not consistent with the LCDM age of the universe at z = 3.91.

This point is emphasised by Drs. Norbert Schartel, Fred Jansen and Prof. Guenther Hasinger in their ESA web-page article Is the universe older than expected?

There are other examples of early iron high abundances: at z = 3.104,
http://xmm.vilspa.esa.es/external/xmm_science/1st_results/pdf/xmm11.pdf ,
(Oct 2000).

And six quasars at z>4
http://www.sron.nl/saxsymp/papers/vignali.ps
(2004)

Garth

 

[Nereid]

Two things (for Garth and roland):

I was responding to the OP (Rumours of the danger posed by HUDF-JD2 to consensus cosmology models) - your reply Garth (a good one) says nothing of HUDF-JD2, and the caveats I made about interpreting the meagre data we have on it.

Quasars are not galaxies; despite decades of intense scrutiny, much remains to be learned about quasars, esp what's really going on in the central engine, and just what the accretion disk (and jet) can, and cannot, produce in the way of nucleosynthesis.

And since we're on the subject, another (more recent) mystery is the formation of the SMBH which lie at the heart of quasars (and the nuclei of - most? all?? - galaxies) - which begat what? Was there only one formation mechanism? Are the all alike anyway??

To be sure, it's a very exciting time to doing astronomy; and an even more exciting time to be doing observational cosmology, a field that's what, less than 50 years old (if you don't count Olbers and the Hubble relationship)? At the same time, it's also frustrating; I doubt that any of us will live to see some of today's central questions in cosmology resolved, let alone the answer to http://mathworld.wolfram.com/HilbertsProblems.html" ("Can physics be axiomatized?" - this is one of only what, three (of 23) that remain, today, unsolved).

 

[Garth]

Hi Nereid.

I was responding to the OP (Rumours of the danger posed by HUDF-JD2 to consensus cosmology models) - your reply Garth (a good one) says nothing of HUDF-JD2, and the caveats I made about interpreting the meagre data we have on it.

I was expanding on roland's point above and I think the age problems are related. I discussed HUDF-JD2 in the former thread linked to above.

The point is that there are now several observations, I have referred to nine, in which old features, particularly high iron content, are observed at (mostly unambiguous) high red shift.

It takes time to synthesise iron and, as I quoted myself saying in post #2 above, we may have to revise our nucleosynthesis models, however, these observations may also be indications that the universe is older than we expect.

One possible explanation is that something is wrong with the way astronomers measure the age of objects in the Universe. The almost-holy red shift-distance-age conversion would therefore be wrong. Fred Jansen, ESA's project scientist for XMM-Newton, explains that this would mean rewriting the textbooks. "If you study the evolution of the Universe, one of the basic rules is that we can tie redshift to age. One distinct possibility to explain these observations is that, at the redshift we are looking at, the Universe is older than we think."
If the older-Universe interpretation is wrong, there is only one other, stranger possibility, according to Jansen. Somewhere in the early Universe there must be undiscovered 'iron factories', producing the metal by unknown physical means. Understandably, Jansen is cautious about this, saying, "This is the less likely solution in my opinion."

That observational fact (old features in an early universe) has to be flagged up when critically accepting the standard theoretical cosmological model.

Garth

 

[sylas]

I realize this is a very old thread, but after fielding questions about HUDF-JD2 in another context, this thread showed up in a google search so it may be worth putting this on record, as others may find it the same way I did.

It seems likely that the original identification of HUDF-JD2 was mistaken. In 2005 it was reported as a galaxy at redshift z~6.5, with a mass of about 6*10¹¹ solar masses. Reference:

• http://arxiv.org/abs/astro-ph/0509768" by Mobasher B. et. al. in Astrophys.J.635:832-844,2005, arXiv:astro-ph/0509768v1

Even then, the report noted an alternative interpretation of a galaxy at about z~2.5 could not be ruled out.

Subsequent work has suggested that the original distance estimate was incorrect, and a lower redshift value is to be preferred.

• http://www.iop.org/EJ/abstract/0004-637X/665/1/257/ by Ranga-Ram Chary et. al (2007) in Astrophys.J. 665, pp 257-264. (also at arXiv:0705.0660v1).

This proposes that it is at z~1.7.

There is other more recent work on high redshift galaxies which make stronger candidates than HUDF-JD2.

Cheers -- sylas

 

[Garth]

Yes, it seems the HUDF-JD2 mystery is being resolved, however there are other high iron content objects in the early universe such as An old quasar in a young dark energy-dominated universe?.

But they too could be resolved with further data or knowledge of metallicity production in the early universe.

Cheers,

Garth

 

[Chronos]

The population I issue remains unresolved. Iron may have evolved more rapidly than suspected in huge, metal deficient primordial stars.

 

[Garth]

The population I issue remains unresolved. Iron may have evolved more rapidly than suspected in huge, metal deficient primordial stars.

Hi Chronos.

I think you mean the Pop III issue!

There certainly is a lot of metallicity at z ~ 4 - 5 as in my post #5 above, but Pop III stars are expected to have very short lifetimes so they should explain it.
Regards,
Garth