How James Webb influences the history of the Universe | November 21, 2023

Over the course of 22 months, the James Webb Space Observatory has repeatedly puzzled and shocked scientists with its data. Naked Science Editorial explainedwhat is really happening to the science of space history thanks to telescope images.

First of all, it is worth noting that the enormous sensitivity of the James Webb allows it to distinguish the faintest objects and observe space in infrared waves. This is very important, because the expansion of the Universe stretches electromagnetic waves, and the light emitted in the first billion years of its existence has long ago turned into infrared radiation. If the galaxy’s rays spent 13 billion years traveling, then we see it as it was 13 billion years ago, just 800 million years after the Big Bang.

Peering into the depths of space, we look into the past. And thanks to the station’s data, we are testing the most incredible theories about how galaxies were formed.

Speaking of light years, it is worth considering that the distance for astrophysicists can be different. That’s why scientists often talk not about distance, but about redshift (z). If necessary, all this is recalculated into any type of distance. There are different ways to measure redshift.

The classic, but most time-consuming way is to obtain the spectrum of an object, that is, measure its brightness at each available wavelength. A simpler method is photometric. The telescope measures the brightness of the galaxy through several light filters, so to speak, “blue”, “green” and “red” into a full spectrum. Photometric z are used when spectroscopic ones are not available.

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Thus, the recently discovered galaxy UNCOVER-z12 is in fourth place in terms of distance from Earth (z = 12.39), and its “discovery neighbor” UNCOVER-z13 is in second place (z = 13.08). In first place (z = 13.2) is the galaxy JADES-GS-z13−0, open all the same “Webb”. Meanwhile, in a scientific article, UNCOVER-z13 is only called a galaxy candidate. In addition, the redshift of the “champion” JADES-GS-z13−0 is spectroscopic, while the “silver winner” UNCOVER-z13 is photometric, that is, not so accurate.

It is important to understand that the vast majority of redshifts measured by Webb are photometric. It is not only less accurate, but also susceptible to distortion. Such a cruel joke on astronomers can be played, among other things, by the abundance of dust in the galaxy or abnormally strong radiation at certain wavelengths. This has already happened, including with Webb.

Let’s assume that most newly discovered galaxies are really as far away as photometry shows. Then cosmology begins to burst at the seams. At the beginning of 2023, an article was published whose authors examined “Webbian” galaxies with photometric 7.4 ≤ z ≤ 9.1 (500−700 million years after the Big Bang). The conclusion is clear: massive galaxies were encountered in that era much more often than our best theories predict.

The mechanism of galaxy formation is a truly problematic area of ​​cosmology. But that’s the beauty: researchers don’t have to use a specific theory of galaxy birth. Recently, astronomer Michael Boylan-Kolchin published work based on the general principles of the modern standard cosmological model – ΛCDM cosmology. For example, that most of the matter in the Universe is dark matter, consisting of particles unknown to science. With rare exceptions, they interact with each other and with ordinary matter only through gravity.

Another component of the Universe is dark energy. According to one of the unproven theses, it differs from both ordinary and dark matter and does not play a significant role in the formation of the first galaxies. However, before Webb’s launch, most cosmologists believed that this was the best way to explain the observed properties of the Universe. Boylan-Kolchin identified the problem: the device sees an unexpectedly large number of bright galaxies at photometric z = 7−10 (500−800 million years after the Big Bang).

It is possible that these results are an observational error due to which Webb could have overestimated the redshift and/or luminosity of the galaxy. But if the data is still correct, then ΛCDM cosmology leaves the only possibility for this. It must be assumed that at that time more than 60% of ordinary – not dark – matter existed in the form of stars, and not interstellar and intergalactic gas. Meanwhile, in space accessible for detailed study, the mass fraction of stars in ordinary matter was only 10−20%.

It is very difficult to understand why in the early Universe it should be several times higher. To accept such an assumption is to explain a strange fact through an even stranger hypothesis. Every scientific paper criticizing Webb’s results uses the thesis: “If the redshifts are confirmed spectroscopically.” A simple fact prevents us from attributing all discrepancies to observational errors: there are too many “illegal” objects.

Already in the first few months of operation, the space observatory found dozens of candidate galaxies with photometric z > 10 (less than 450 million years after the Big Bang). It is unlikely that all of them can be false. The sensitive Webb has invaded a completely new area, and it is quite possible that here the Universe has some unpleasant surprise in store for persistent observers. If the photometric results of the spacecraft are nevertheless confirmed, many things will have to change in ΛCDM cosmology. Most likely, the changes will affect the most mysterious substances – dark matter and energy. Fortunately, there are plenty of alternative theories about them.

Recent Study showedthat the Universe may turn out to be a black hole. This conclusion was made thanks to the study of a global map of the mass and radii of objects, ranging from subatomic particles to superclusters of galaxies.

Olesya Mayevskaya

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