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Glittering in the sunlight as it recedes from the view of the final stage of the Ariane 5 rocket that launched it, NASA’s James Webb Space Telescope heads towards its final destination with perhaps the maximum amount of fuel we could have hoped for. Instead of a planned 5.5-10 years of science operations, we’re anticipating a 20+ year lifetime for JWST.
Now fully deployed and commissioned, JWST will soon begin science operations.
This three-panel animation shows the difference between 18 unaligned individual images, those same images after each segment had been better configured, and then the final image where the individual images from all 18 of the JWST’s mirrors had been stacked and co-added together. The pattern made by that star, known as the “nightmare snowflake,” can be improved upon with better calibration.
Although many cosmic questions will certainly be answered, the greatest revolutions arise unexpectedly.
This is a simulated JWST/NIRCam mosaic that was generated using JAGUAR and the NIRCam image simulator Guitarra, at the expected depth of the JADES Deep program. It is quite likely that in its first year of science operations, James Webb will break many records that Hubble set over the course of its 32 year (and counting) lifetime, including records for most distant galaxy and most distant star.
Here are five questions that JWST could conceivably answer, changing our cosmic conceptions forever.
Although Spitzer (launched 2003) was earlier than WISE (launched 2009), it had a larger mirror and a narrower field-of-view. Even the very first JWST image at comparable wavelengths, shown alongside them, can resolve the same features in the same region to an unprecedented precision. This is a preview of the science we’ll get.
1.) Do biosignatures exist on nearby super-Earths?
If other inhabited planets exist in our galaxy, near-future technology that will be at our disposal within this century, or perhaps even this decade, may be able to first uncover it. Equipped with both a coronagraph and tremendous spectroscopic infrared capabilities, the JWST could, if we’re very lucky, find the first evidence for life beyond our Solar System.
If unexpected signs of life exist in the atmospheres of super-Earth worlds, JWST could reveal them.
When an exoplanet passes in front of its parent star, a portion of that starlight will filter through the exoplanet’s atmosphere, allowing us to break up that light into its constituent wavelengths and to characterize the atomic and molecular composition of the atmospehre. If the planet is inhabited, we may reveal unique biosignatures.
They would be our first-ever hints of life outside the Solar System.
When starlight passes through a transiting exoplanet’s atmosphere, signatures are imprinted. Depending on the wavelength and intensity of both emission and absorption features, the presence or absence of various atomic and molecular species within an exoplanet’s atmosphere can be revealed through the technique of transit spectroscopy.
2.) Are there pristine stars in ultra-distant galaxies?
The very first stars and galaxies that form should be home to Population III stars: stars made out of only the elements that first formed during the hot Big Bang, which is 99.999999% hydrogen and helium exclusively. Such a population has never been seen or confirmed, but some are hopeful that the James Webb Space Telescope will reveal them. In the meantime, the most distant galaxies are all very bright and intrinsically blue, but not quite pristine.
By understanding and measuring second-generation stars, JWST could find additional, first-generation starlight alongside them.
An illustration of CR7, the first galaxy detected that was thought to house Population III stars: the first stars ever formed in the Universe. It was later determined that these stars aren’t pristine, after all, but part of a population of metal-poor stars. The very first stars of all must have been heavier, more massive, and shorter-lived than the stars we see today, and by measuring and understanding the light from the metal-poor stars, we could disentangle any additional light to search for evidence of a truly pristine stellar population.
3.) Are black holes energetically active in dusty, early galaxies?
This artist’s impression of the dusty core of the galaxy-quasar hybrid object, GNz7q, shows a supermassive, growing black hole at the center of a dust-rich galaxy that’s forming new stars at a clip of some ~1600 solar masses worth of stars per year: a rate that’s about 3000 times that of the Milky Way.
By exquisitely measuring the energy re-radiated by dust, JWST could reveal shrouded supermassive black hole activity.
In this comparison view, the Hubble data is shown in violet, while ALMA data, revealing dust and cold gas (which themselves indicate star-formation potential), is overlaid in orange. Clearly, ALMA is revealing not only features and details that Hubble cannot, but sometimes, it shows the presence of objects that Hubble cannot see at all. With JWST data folded in, we might be able to identify whether black holes precede the presence of stars and galaxies themselves.
4.) Was the Universe born with black holes?
This tiny sliver of the GOODS-N deep field, imaged with many observatories including Hubble, Spitzer, Chandra, XMM-Newton, Herschel, the VLT and more, contains a seemingly unremarkable red dot. That object, a quasar-galaxy hybrid from just 730 million years after the Big Bang, may be key to unlocking the mystery of galaxy-black hole evolution. Once speculative, the evidence for the physical existence and ubiquity of black holes is now overwhelming.
By investigating the earliest galaxies, JWST will reveal their formation history.
If you begin with an initial, seed black hole when the Universe was only 100 million years old, there’s a limit to the rate at which it can grow: the Eddington limit. Either these black holes start off bigger than our theories expect, form earlier than we realize, or they grow faster than our present understanding allows to achieve the mass values we observe. Examining quasar-galaxy hybrids may hold the key to unraveling this mystery.
If black holes preceded the first stars, JWST could discover the critical evidence.
If the Universe was born with primordial black holes, a completely non-standard scenario, and if those black holes served as the seeds of the supermassive black holes that permeate our Universe, there will be signatures that future observatories, like the James Webb Space Telescope, will be sensitive to.
5.) How are dark matter-free galaxies made?
Many nearby galaxies, including all the galaxies of the local group (mostly clustered at the extreme left), display a relationship between their mass and velocity dispersion that indicates the presence of dark matter. NGC 1052-DF2 is the first known galaxy that appears to be made of normal matter alone, and was later joined by DF4 in 2019. Galaxies like Segue 1 and Segue 3, however, are particularly dark matter-rich; there are a wide diversity of properties, and the dark matter-free galaxies are only poorly understood.
Both leading formation mechanisms require galactic interactions to separate dark matter from normal matter.
The galaxy NGC 1052-DF4, one of the two satellite galaxies of NGC 1052 determined to be devoid of dark matter internally, shows some evidence of being tidally disrupted; an effect more easily seen in the panel at right, once the surrounding light sources are accurately modeled and removed. Galaxies such as this are unlikely to live long in rich environments without dark matter to hold them together, but their formation mechanisms are still debated.
If there’s more to the story, JWST will teach it to us.
In early 2022, for the first time, a cosmological simulation has produced dark matter-deficient galaxies that match our observed galaxies that lack dark matter across a wide variety of properties. In the future, better observations and larger data sets will be able to test these predictions robustly, and determine the effectiveness of the simulation.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.
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