We have a new contender for the title of “oldest known galaxy”: it has a redshift of z = 7.51, corresponding to an age only 700 million years younger than the universe as a whole, and has been assigned the code z8_GND_5296. Discoveries like this happen fairly often, as there is a sustained effort of astronomers staring at little red dots with similarly arcane designations in the hope of teasing out a little more information about the early evolution of galaxies.
This particular find has three important, and interlinked, aspects. First, the new galaxy’s spectrum reveals it to be forming stars at a rate of about 330 solar masses per year, which is more than an order of magnitude greater than the expected value of 10 per year (and about 100 times that of the modern Milky Way). The second find is that another object in the same small survey of potential ancient galaxies also has an anomalously high star formation rate, strongly suggesting that it’s not some kind of fluke or coincidence. The implication is that there were many more stars being produced in the early universe than we thought.
The third point is pretty tangential as far as we are concerned, but might be the most important. Candidate galaxies for this search were selected from Hubble images on the basis of their colour – redness implies age – but such samples are contaminated by younger objects that merely appear old. The wheat was separated from the chaff, so to speak, via the investigation of Lyman-alpha (Lyα) emission (a particular wavelength produced by the movement of an electron in a hydrogen atom from a certain exited state down to the ground state). The researchers expected to find via this method that 6 of their sample galaxies were really ancient, but only one was actually found. They suspect that the process of reionisation, occurring around the time that the light was released from these galaxies, is interfering with their Lyα measurements by absorbing light at that wavelength. The implication here is that the presence or absence of Lyα radiation in ancient galaxies found via other methods could be used to investigate and precisely date the reionisation period.
Brian Thomas writes Secrets from the Most Distant Galaxy. He offers many alleged problems with this research, though the third issue above is not among them:
An international team recently announced discovery of a new record for the most distant galaxy and claimed they were viewing this galaxy at “an epoch only 700 million years after the Big Bang.” However, the leap from a distant light measurement to millions of years and a Big Bang history came tightly packaged with scientific-sounding but unsupported statements that attempt to explain this galaxy’s secrets.
The overarching point of Thomas’ article is that he doesn’t like it when scientists take things like the big bang as read, standing upon the shoulders of giants rather than demonstrating the same results again and again. In many ways it is quite like a geocentrist, discussing the orbital parameters of a newly-discovered asteroid, taking umbrage at the “scientific-sounding but unsupported” assumption of Kepler’s Laws of planetary motion and reassuring his followers that the small probability of a collision with Earth does not constitute a threat to their warped cosmology.
To recap: we have a new galaxy with a redshift of z = 7.51 – beating the previous record holder of z = 7.2 – which is producing more stars than expected. The z-value implies an age of only 700 million years after the big bang, which occurred 13.8 billion years ago.
Some of Thomas’ problems are quite fundamental: while he recognises that the redshift implies both the expansion of the universe and great distance – possibly too great of a concession if one were building a young Earth creationist cosmology from the ground up, but the ICR seems content to place their interpretations haphazardly atop our existing knowledge – but obviously doesn’t like the implication of great age:
[Dominick] Riechers wrote [in his Nature news article, not open access] that the galaxy’s light “reaches us with a time delay” because “light emitted by stars in far-off galaxies travels at a finite velocity.” But scientists have not measured, and probably cannot measure, the one-way speed of light. In fact, other experiments have shown that the round-trip speed of light is the same relative to any observer regardless of the speed with which the observer travels through space.
In other words, science leaves open the possibility that light travels at infinite velocity toward the observer. If so, then this distant galaxy would not represent any ancient epoch.
The infinite speed of light, which allows objects that are billions of light years away not to be billions of years old, is part of Jason Lisle’ warped cosmology – known as the anisotropic synchrony convention – which we have met previously. Thomas could just have easily raised the possibility that God created the light in transit, which has long been the traditional YEC response to the starlight problem (the question of how god could have created the heavens during creation week yet we see light from objects too distant for light to have reached us in this time). Either God deceitfully created photons to allow Him to form the heavens with the appearance of age but within the time constraints of the text, or he warped the very fabric of the universe for the same end. When confronted with this issue creationists must pick their poison: Lisle’s explanation is more sciencey-sounding – and he’s on the staff these days – so they’re going with his these days.
We move to Thomas’ second issue:
Moreover, though the light from z8_GND_5296 does show genuine features of unimaginably great distance, it does not reflect expected aspects of a Big Bang. For example, it is enriched in heavy elements; whereas, the epoch in which it supposedly belongs should instead show just the lightest elements: hydrogen, helium, and traces of lithium.
Astronomers define “metals” as any element other than hydrogen or helium. While non-metals were produced in the big bang itself (along with, as Thomas says, trace amounts of lithium and also a very tiny amount of beryllium), metals accumulate in the universe via stellar fusion – those enamoured with the notion of fine-tuning may be aware that the constants universe seems to be set up precisely so that this can happen, something which a young Earth does not require. (Those who look more to the weak anthropic principle naturally counter that we would not exist in a universe where this were not so, and therefore would not be around to complain.) The paper looked specifically at evidence for oxygen, and found that there was some:
This very high [O iii] equivalent width constrains the abundance of metals in this galaxy, as highly enriched stars do not produce hard-enough ionizing spectra, and very low-metallicity systems do not have enough oxygen to produce strong emission lines. Of the metallicities available in our models (0.02, 0.2, 0.4 and 1.0 times solar), only models with a metal abundance of about 20–40% of solar have [O iii] equivalent widths >300 Å. Thus, even at such early times, a moderately chemically enriched galaxy could form. However, because of the discreteness of the model metallicities, further analysis is needed to draw more quantitative conclusions about the metallicity—particularly its lower limit.
The amount, though poorly constrained, is still significantly less than in a modern star like the sun – just as you would expect. But is it still too high? While Thomas says that it is, the paper gives no such indication. The Nature news article, for its part, offers up the following tidbit while talking about the new distance record:
The existence of only one more-distant object [than z8_GND_5296] is securely known, owing to the explosion of a massive star about 70 million years earlier. However, the galaxy associated with this event has remained undetected.
Metals are, as I said, formed in stars – particularly during supernova events, which also provide a mechanism for spreading them around. The implication of a supernova that is even older shows that metals were already available at greater than the minimal level that Thomas insists was the case, although this does not fully answer the question. The issue of too much metal has come up in early galaxy stories before, but I don’t know if it’s a merely a case of “we didn’t expect to find it” or if it’s truly impossible (I think the former).
Next, Thomas claims that galaxies could not have existed at this time at all:
Also, if the galaxy really developed that “soon” after the Big Bang, it should not yet have formed so many brightly burning stars, and those stars should not yet have clumped together into a mature galaxy. Other distant galaxies carry similar difficulties.
That last sentence is cited to a 2006 Acts & Facts article by David Coppedge, and a 2011 DpSU covered here. Thomas contends that this galaxy is “mature,” and that it should not be so at this age. It’s true that a mature galaxy should not be 13 billion years old, but this is not a mature galaxy, merely a galaxy. The claim that it is like our own is based merely on assertion – for counter-evidence see the “moderate” metallicity, which is definitely too low for that to be true.
More generally, creationists like Thomas and Coppedge claim that the universe was “mature at birth” – that as far back as you look you only see mature galaxies like our own. On this subject a recently-released diagram of Hubble pictures is informative:
This shows pictures of spiral galaxies, like the Milky Way, arranged by their age. You may quibble that the oldest galaxies shouldn’t look exactly how they do, but to deny that there is a progression here of any sort is to deny the evidence outright.
Moving along a bit we get to those extra stars:
Finally, the study authors interpreted the mere existence of this galaxy’s already-formed stars as evidence that “The galaxy z8_GND_5296 is forming stars at a very high rate.” How did they do this? Not by observing any new star form but by using “the best-fitting stellar population models.” Undoubtedly, those models assume that stars form naturally, another idea that science has not confirmed. No one has observed a star being formed.
Stars take millions of years to form: nobody has been looking for this long, and until they have creationists are unlikely to admit that it is even possible. But just as we can get pictures like the above of galaxies in various stages of formation, so too can we get snapshots of stars themselves. It becomes clear, once you look at enough stars, that there are patterns here too: one star, we can determine, will later look like a second via a stage where it takes the appearance of a third. We have not seen it, but we can be sure that it will occur.
Some of this record-setting galaxy’s secrets, like its very great distance, are straightforward. But others, like its mature appearance, its elemental composition, and its dense population of bright stars, challenge Big Bang history. Marek Kukula of the Royal Observatory in Greenwich was not involved in the study but told BBC News, “This, along with some other evidence, shows that there are already quite surprisingly evolved galaxies in the very early Universe.”
“This high star-formation rate maybe is a clue as to why these galaxies can form so quickly.”
And the BBC article goes on to say:
Prof Alfonso Aragon-Salamanca, from the University of Nottingham, added: “This is an important step forward, but we need to continue looking for more.
“The further away we go, the closer we will get to discovering the very first stars that ever formed in the Universe. The next generation of telescopes will make this possible.”
But Dr Stephen Serjeant from the Open University said: “Chasing ultra-high redshift galaxies is a very exciting but equally very difficult game, and many claims of extremely distant galaxies have since turned out to be more nearby interlopers.”
There is no need to rely on the possibility that this galaxy wont pan out, however. This galaxy may be “surprisingly evolved,” but this is a “more than nothing” comment, rather than meaning quite what Thomas implies.
He concludes his article:
In other words, the real secret that z8_GND_5296 reveals is that naturalistic astronomers too easily swap speculative models for empirical knowledge. Perhaps galaxies are so distant, not because they hearken back to any early epoch, but because they illustrate the greater immensity of their Creator.
A creator who builds whole galaxies that are primitive, but not quite as primitive as expected, for reasons ineffable but probably not very nice. A creator who warps the very universe to accommodate the literal meaning of a poetic line of text. A creator who… you get the idea.
Somebody is certainly using “scientific-sounding but unsupported statements” to “swap speculative models for empirical knowledge,” but it would seem to be Thomas himself. Whatever it takes to keep the faith, I suppose.
I didn’t manage to work the name in, but the paper that the new discovery was announced in was called “A galaxy rapidly forming stars 700 million years after the Big Bang at redshift 7.51,” published last month in Nature. This isn’t open access, but the paper is also available at arXiv as astrophysics papers often are. This Astrobites post by Nick Hand on the galaxy is to be recommended, while Timothy V. Reeves seems to be the go-to guy for information on Lisle’s anisotropic synchrony convention and its implications, and has a generally interesting blog. While looking around on the web for redshift information I came across a flash program showing how it can be measured up to z = 1.
I think that’s about everything.