7 stunning insights from the first ‘Deep Field’ image from the James Webb Space Telescope
(ORDO NEWS) — Even with an exposure of only 12.5 hours, the James Webb telescope managed to capture such a “deep field” image from which we can learn many valuable lessons.
Ethan Siegel
On July 11 and 12, 2022, our understanding of the universe changed once and for all. These days the whole world saw the first pictures taken by the James Webb space telescope.
In contrast to previous releases of images taken by this telescope, which were only images used to calibrate, test and start equipment, the new images:
- Were made using many tools and filters
- Were made for the purpose of collecting scientifically valuable data
- They were made so that for the first time in history they can be folded into full-color images that truly delight and delight the eye
The very first published image was a “deep field” image of the massive star cluster SMACS 0723. Using a variety of filters and instruments, the James Webb telescope “observed” this piece of space for 12.5 hours.
Although this may seem like a very long time, it is only 2% of the time that the Hubble telescope spent on its deep field image: it created its first deep field image from 342 images over a period of 23 days.
Based on the first image of Webb, we can draw seven startling conclusions that will have a significant impact on the future of science.
1. The James Webb telescope outperforms the Hubble more than we expected
If we compare the capabilities of Webb and Hubble, it becomes clear that our latest space telescope can do a lot more in less time.
Hubble has only a primary mirror with a diameter of 2.4 meters, while Webb has a segmented mirror with a diameter of 6.5 meters. As a result, Webb’s resolution is 270% higher (for light of the same wavelength), and its luminosity is 730% greater than that of Hubble.
Thinking purely in terms of the laws of optics, exactly how much better and faster Webb should be than Hubble – without taking into account the advantages that Webb has in terms of cooling, wavelength range and instruments.
In other words, during the same observation time, Webb should “collect” 730% more light than Hubble. However, Webb – as you can see for yourself above by comparing his image of the SMACS 0723 galaxy cluster with the Hubble image – does even better.
Hubble’s operating time is divided into “orbits”: so, from its position in low Earth orbit, it makes a complete revolution around our planet every 96 minutes.
In total, Hubble needed six “orbits” to create a composite image: four in the optical range and two in the infrared range. Based on simple math, six revolutions multiplied by 96 minutes per revolution equals 9.6 hours (576 minutes).
However, in the final image taken by Hubble, only the data collected by it for 3.4 hours or 203 minutes were included, although the telescope devoted almost three times more time to observing its object. In comparison, “Webb observed his target for 12.5 hours and received total data for all those 12.5 hours.
What is the difference?
The location from which the observation is made. Since Hubble is in Earth orbit, it spends more than 50% of its time interacting with the Earth (and the Earth’s atmosphere) and can only obtain useful data when nothing prevents it from observing its primary target.
Meanwhile, Webb is located about 1.5 million kilometers from Earth, at the L2 Lagrange point. It always faces away from the Sun, from the Earth and from the Moon. He does not have to face these obstacles in his observations at all.
As a result, the efficiency of its observations is almost 100%, while that of Hubble is less than 50%. This high efficiency will be shared across all of Webb’s observations, so the new telescope will be supplying scientists with higher quality data at a faster rate than Hubble has ever been able to.
2. In those parts of space that are commonly called space voids, it is not always empty
In theory, we knew that this was the case, but with the first “deep field” images taken by Webb, we had the necessary evidence. There are vast regions of space in which there are no stars or galaxies at all.
Since these “voids” were discovered, scientists have wondered if there could be objects that are too dim, small, low-mass, or too far away for us to see with the technology we have, or if these voids are actually were 100% empty.
As the first images from the Webb telescope showed, there are many areas of space that Hubble seemed empty, but in which Webb was able to make out a lot of different objects. Yes, these patches do remain relatively “sparsely populated” regions of space, but they are not empty, as some have hoped or feared.
Webb can not only find these objects, but in many cases can clearly see and study their properties, while Hubble could not even see them.
This will help us achieve one of the main scientific goals of the James Webb Project, which is to tell us in great detail about how our universe came into being and how it came to be the way it is today.
3. We will finally be able to see the structure of the largest, most massive early galaxies
When you look at the faintest, most distant objects that the Hubble Space Telescope has been able to detect, they most often look like ordinary “spots” in the sky. But with Webb’s improved resolution, we can see that these distant objects are galaxies, and that these galaxies often have a discernible structure.
We know that accretion and mergers play an important role in the evolution of galaxies and that the relative proportion of stars that are influenced by each other changes over time.
In addition, we already know that galaxies within galaxy groups or clusters evolve differently in terms of their shape (astronomers call this “morphology”) than more isolated galaxies.
But here it is important to pay attention to the following point: a 270% increase in resolution in reality means an increase in the number of pixels per light source by about 700%.
A galaxy that is only 3×3 pixels for Hubble would already be 8×8 pixels for Webb. By seeing how the shapes and configurations of galaxies change in cosmic time and space, we can understand how our universe has grown throughout its history.
4. The era of “deceiver galaxies” has come to an end
If you are not a professional, you most likely have not heard about this problem: many of those galaxies that we at some point declared “the most distant” actually turned out to be not galaxies at all.
The reason is simple and banal: with the current technology at our disposal, we could not conduct a full-fledged spectroscopy of the most distant objects.
What do I mean by “full spectroscopy”?
Spectroscopy involves splitting incoming light into waves of different wavelengths and looking for either emission lines (peaks at certain wavelengths) or absorption spectral lines that correspond to quantum mechanical transitions of certain elements.
If you can get a lot of lines by looking at an element, you can determine how much the wavelength of the emitted wave has changed due to the expansion of the universe.
With the Hubble telescope, we cannot make this analysis for the most distant galaxies, because its wavelength sensitivity does not cover the infrared range. If we talk about the most distant “candidates” for galaxies, we did not conduct a full-fledged spectroscopy for about ten years.
However, with the advent of the James Webb telescope and its extremely high sensitivity to wavelengths of less than 2000 nanometers, all these unknowns will simply disappear.
Any galaxy with a redshift in its spectrum, such as HD1 and GN-z11, will now have to undergo a full spectroscopic “confirmation” procedure, which has never happened before.
As the first spectra taken from Webb show, we can now do this for all the galaxies that we want to check, and we will get data on the presence of oxygen, hydrogen and neon lines in the spectra of galaxies, if they are there.
Astronomers are most often of two types: those who make sensational claims about what is happening in space with only a hint of the necessary evidence, and those who do not accept such claims until the evidence in their favor is irrefutable.
Now that we have “James Webb”, we finally have the opportunity to collect the hard evidence needed to accurately determine the properties of galaxies, and no longer need to guess and make assumptions. Science is not about analyzing scarce data and choosing what to believe.
Science should show us what is real, true and beyond doubt. Thanks to the possibilities of “Webb” in our reasoning about the Universe, we will very soon replace “we think” with “we know.”
5. We will be able to refute all variations of the modified gravity hypothesis
One of the great things about dark matter theory is that it explains so many observed phenomena from so many different angles with just this one addition. A theory of the universe in which dark matter is present can explain:
- How individual galaxies rotate and interact
- How galaxies group and form clusters
- How galaxies move within clusters
- How gravitational lensing distorts and magnifies objects behind galaxies
- What does the large-scale structure of the universe look like?
However, scientists are trying to explain some of these phenomena not with the help of dark matter, but with the help of the idea of ​​changing the laws of gravity.
In the process of analyzing many of the properties of individual galaxies, this hypothesis looks quite promising when considered in isolation, but otherwise it does not help so much.
Some variants of the modified gravity hypothesis predict that the behavior of rotating galaxies will change over cosmic time; other versions indicate that young rotating galaxies and old rotating galaxies should have similar rotation curves.
Now that we have the resolution and spectroscopic capabilities of Webb at our disposal, we can apply them to the rotating galaxies observed throughout the universe and refute some variation of the modified gravity hypothesis.
It also means that now we will be able to test our theories of dark matter, which we could not do before. Whatever we find out as a result, it will be data on how the Universe actually behaves.
6. We will get more detailed images of the centers of galaxy clusters
Have you ever wondered, looking at a massive cluster of galaxies, what happens in the very center and on the outskirts of the brightest, most massive galaxy located in the middle of the cluster? We managed to consider only the clusters of galaxies closest to us, and we learned only:
How much gas is there
What do stars look like inside them
How many globular star clusters are inside them
How many dim satellite galaxies are around them
However, in the case of most clusters of galaxies, we can only see scattered, excess light, called intra-cluster light, that comes from them.
But now, with Webb’s capabilities at our disposal, we can see what structures are present around the central galaxies.
This telescope will even be able to see small, dim galaxies that would otherwise simply “merge” together at a lower resolution.
We may even be able to use the data to explain the distribution of light sources within the cluster, as well as to reveal the properties of satellite galaxies and globular clusters in the halo of galaxies, which has never been done before.
In Webb’s very first deep-field image, we’re already seeing things we wouldn’t be able to see without him.
7. Webb’s mid-infrared imagery can detect the presence of organic matter, such as hydrocarbon compounds, throughout the universe
Yes, it’s true: purely visually, the shorter wavelength Webb shots are the most spectacular. The images taken by NIRCam, which contain wavelengths from about 600 to 5000 nanometers, are much higher resolution than the MIRI images, which cover wavelengths from 5000 to 28,000 nanometers.
After all, the resolution of your telescope is determined by the number of wavelengths of light that can fit in the diameter of its primary mirror, and with a fixed 6.5 meter diameter mirror, NIRCam images will give you higher resolution than MIRI every time.
But the ability to pick up mid-infrared wavelengths makes it possible to see something that can’t be seen with near-infrared photography, namely cosmic dust.
This neutral matter is not only the main “ingredient” in the process of star formation, but also contains molecules that emit light only in a certain range.
The galaxies glowing “green” in the MIRI images contain various chemical compounds, including hydrocarbons, which indicate the ability of these galaxies to host habitable worlds. All this data, put together, will help to reveal the greatest number of secrets of our Universe.
The conclusions listed above are just the beginning of the great space science that is kicking off with the first images from the James Webb telescope.
Many of the galaxies that are arced or visually very red are undergoing gravitational lensing, and the first data from Webb is good enough to tell us immediately which points of light are multiple images of the same galaxy and which are – different galaxies.
Now that all of Webb’s instruments are up and running, this “deep field” image shows us the universe like we’ve never seen it before.
The most important thing to keep in mind is that this “deep field” image, like all of the images that were included in the first batch of published images from the Webb Telescope, is data collected in less than a day.
By comparison, Hubble has been operating for 32 years, which means that Webb is capable of surpassing it on many fronts. More than 20 years of work with “James Webb” are ahead of us, and new discoveries are just beginning.
As Edwin Hubble eloquently put it, “with increasing distance, our knowledge becomes more and more scarce and disappears altogether. Eventually we reach the dim limit – the extreme limit of the capabilities of our telescopes.
There we begin to measure shadows, look for some landmarks among the ghostly errors in measurements which can hardly be called significant. The search will continue. And only when our empirical resources are exhausted, we will have to move into the foggy space of hypotheses.
With the unprecedented capabilities of the James Webb telescope at our disposal, we are just beginning to see our universe literally in a whole new light.
—
Online:
Contact us: [email protected]
Our Standards, Terms of Use: Standard Terms And Conditions.
