How James Webb will reveal what Hubble missed

Our Universe, no matter how distant we look, continues revealing stars and galaxies evermore.

The GOODS-North survey, shown here, contains some of the most distant galaxies ever observed, a great many of which are already unreachable by us. As time marches forward, more and more galaxies suffer this same fate, as even at the speed of light, the relentless cosmic expansion disconnected them from ourselves. (Credit: NASA, ESA, and Z. Levay)

But back at the Big Bang, there were absolutely none.

The farther away we look, the closer in time we’re seeing towards the Big Bang. As our observatories improve, we may yet reveal the very first stars and galaxies, and find the limits to which, beyond them, there are none. (Credit: Robin Dienel/Carnegie Institution for Science)

Stars and galaxies require hundreds of millions of years of cosmic evolution to form.

At the earliest times, starlight from the first luminous objects would be blocked by the neutral matter permeating space at that time. But by measuring longer-wavelength signatures, such as those emitted by carbon monoxide molecules in the gas, distant galaxies can be seen by other observatories, like ALMA, that ultraviolet, optical, and near-infrared observatories would otherwise miss. (Credit: R. Decarli (MPIA); ALMA (ESO/NAOJ/NRAO))

Today, 13.8 billion years after the Big Bang, looking farther away in space means observing farther back in time.

Fewer galaxies are seen nearby and at great distances than at intermediate ones, but that’s due to a combination of galaxy mergers and evolution and also being unable to see the ultra-distant, ultra-faint galaxies themselves. Many different effects are at play when it comes to understanding how the light from the distant Universe gets redshifted. (Credit: NASA / ESA)

Although Hubble has given us unprecedented views, even it possesses limits.

The Hubble eXtreme Deep Field (XDF) may have observed a region of sky just 1/32,000,000th of the total, but was able to uncover a whopping 5,500 galaxies within it: an estimated 10% of the total number of galaxies actually contained in this pencil-beam-style slice. The remaining 90% of galaxies are either too faint or too red or too obscured for Hubble to reveal, but when we extrapolate over the entire observable Universe, we expect to obtain a total of ~2 trillion galaxies within the visible Universe. (Credit: HUDF09 and HUDF12 teams; Processing: E. Siegel)

With restricted wavelengths, a small aperture, cosmic dust, and expansion to contend with, our current views reflect these constraints.

Only because this distant galaxy, GN-z11, is located in a region where the intergalactic medium is mostly reionized, can Hubble reveal it to us at the present time. To see further, we require a better observatory, optimized for these kinds of detection, than Hubble. James Webb provides, with cooler temperatures, longer wavelength sensitivities, and larger apertures, will soon provide precisely that. (Credit: NASA, ESA, P. Oesch and B. Robertson (University of California, Santa Cruz), and A. Feild (STScI))

NASA’s James Webb Space Telescope, fortunately, will overcome Hubble’s many impediments.

James Webb will have seven times the light-gathering power of Hubble, but will be able to see much farther into the infrared portion of the spectrum, revealing those galaxies existing even earlier than what Hubble could ever see. Galaxy populations seen prior to the epoch of reionization should abundantly be discovered, including at low masses and low luminosities, by James Webb beginning in 2022. (Credit: NASA/JWST Science Team; composite by E. Siegel)

With a larger aperture, cooler temperatures, and wavelength sensitivity ~15 times as long as Hubble’s, Webb will shatter these cosmic records.

A portion of the Hubble eXtreme Deep Field that’s been imaged for 23 total days, as contrasted with the simulated view expected by James Webb in the infrared. With the COSMOS-Webb field expected to come in at 0.6 square degrees, it should reveal approximately 500,000 galaxies in the near-infrared, uncovering details that no observatory to date has been able to see. While NIRcam will produce the best images, the MIRI instrument may produce the most profound data. (Credit: NASA/ESA and Hubble/HUDF team; JADES collaboration for the NIRCam simulation)

More distant, more obscured, and intrinsically fainter galaxies will all be revealed.

The COSMOS-Web survey (renamed from COSMOS-Webb, as it will survey a portion of the cosmic web) will map 0.6 square degrees of the sky — about the area of three full Moons — using the James Webb Space Telescope’s Near Infrared Camera (NIRCam) instrument, while simultaneously mapping a smaller 0.2 square degrees with the Mid Infrared Instrument (MIRI). It should revolutionize our understanding of the reddest, faintest, dustiest, and earliest/most distant galaxies of all. (Credit: Jeyhan Kartaltepe (RIT); Caitlin Casey (UT Austin); and Anton Koekemoer (STScI) Graphic Design Credit: Alyssa Pagan (STScI))

Webb’s first wide, deep-field survey — COSMOS-Web — will blow all previous deep-fields away.

The full DREaM simulated galaxy catalog was used to provide a full square degree’s view of what a survey with James Webb would be able to see. Included in this view are many times the total number of galaxies that Hubble, even with its deepest, longest views, was capable of revealing. (Credit: B. Villasenor, N. Drakos, R. Hausen, B. Robertson (UCSC))

Simulations, like the Deep Realistic Extragalactic Model (DREaM) catalog, set observational expectations for Webb.

This view of a portion of the DREaM simulated galaxy catalog provides a snippet of sky that might correspond, statistically, with what James Webb expects to see. This particular snippet showcases a distant view that’s filled with faint galaxies; easier to find where there are a dearth of bright ones. (Credit: Nicole Drakos, Bruno Villasenor, Brant Robertson, Ryan Hausen, Mark Dickinson, Henry Ferguson, Steven Furlanetto, Jenny Greene, Piero Madau, Alice Shapley, Daniel Stark, Risa Wechsler)

From the faintest galaxies,

This view of a portion of the DREaM simulated galaxy catalog provides a snippet of sky that might correspond, statistically, with what James Webb expects to see. This particular snippet showcases an incredibly rich region of relative nearby galaxies clustered together, which could provide Webb with an unprecedented view of galaxies magnified by strong and weak gravitational lensing. (Credit: Nicole Drakos, Bruno Villasenor, Brant Robertson, Ryan Hausen, Mark Dickinson, Henry Ferguson, Steven Furlanetto, Jenny Greene, Piero Madau, Alice Shapley, Daniel Stark, Risa Wechsler)

to the richest clusters,

This view of a portion of the DREaM simulated galaxy catalog provides a snippet of sky that might correspond, statistically, with what James Webb expects to see. This particular snippet showcases just how empty some of the emptiest parts of space will, and won’t, appear to James Webb’s eyes. (Credit: Nicole Drakos, Bruno Villasenor, Brant Robertson, Ryan Hausen, Mark Dickinson, Henry Ferguson, Steven Furlanetto, Jenny Greene, Piero Madau, Alice Shapley, Daniel Stark, Risa Wechsler)

to mostly empty cosmic voids,

This view of a portion of the DREaM simulated galaxy catalog provides a snippet of sky that might correspond, statistically, with what James Webb expects to see. This particular snippet showcases a region that appears to have only distant and faint galaxies, an important component in understanding underdense regions of the cosmic web. (Credit: Nicole Drakos, Bruno Villasenor, Brant Robertson, Ryan Hausen, Mark Dickinson, Henry Ferguson, Steven Furlanetto, Jenny Greene, Piero Madau, Alice Shapley, Daniel Stark, Risa Wechsler)

to the deepest depths of far-off space,

This view of a portion of the DREaM simulated galaxy catalog provides a snippet of sky that might correspond, statistically, with what James Webb expects to see. This particular snippet showcases massive foreground galaxies contrasted against ultra-distant, deep ones; where those views coincide, gravitational lensing could reveal the deepest objects visible to Webb of all. (Credit: Nicole Drakos, Bruno Villasenor, Brant Robertson, Ryan Hausen, Mark Dickinson, Henry Ferguson, Steven Furlanetto, Jenny Greene, Piero Madau, Alice Shapley, Daniel Stark, Risa Wechsler)

and much, much more,

This view of a portion of the DREaM simulated galaxy catalog provides a snippet of sky that might correspond, statistically, with what James Webb expects to see. This particular snippet showcases a very, very red and bright galaxy just below the center: one of the oldest and most distant, but still bright, galaxies that Webb will be anticipated to observe. (Credit: Nicole Drakos, Bruno Villasenor, Brant Robertson, Ryan Hausen, Mark Dickinson, Henry Ferguson, Steven Furlanetto, Jenny Greene, Piero Madau, Alice Shapley, Daniel Stark, Risa Wechsler)

we know what to scientifically expect.

This view of a portion of the DREaM simulated galaxy catalog provides a snippet of sky that might correspond, statistically, with what James Webb expects to see. This particular snippet showcases a rich foreground cluster with a variety of background objects of interest. (Credit: Nicole Drakos, Bruno Villasenor, Brant Robertson, Ryan Hausen, Mark Dickinson, Henry Ferguson, Steven Furlanetto, Jenny Greene, Piero Madau, Alice Shapley, Daniel Stark, Risa Wechsler)

Only by comparing theory with observation can we understand the Universe we inhabit.

The cosmic web is driven by dark matter, which could arise from particles created in the early stage of the Universe that do not decay away, but rather remain stable until the present day. The smallest scales collapse first, while larger scales require longer cosmic times to become overdense enough to form structure. The voids in between the interconnected filaments seen here still contain matter: normal matter, dark matter and neutrinos, all of which gravitate. The formation of cosmic structure leads to galaxies as well, and by comparing our expectations with observations, we can truly test our understanding of the cosmos. (Credit: Ralf Kaehler and Tom Abel (KIPAC)/Oliver Hahn)

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.