When NASA's James Webb Space Telescope begins scientific operations in 2022, one of its first missions will be to record the universe's oldest structures.
- COSMOS-Webb is the biggest mission Webb will undertake during its first year, with a broad and deep survey of half a million galaxies.
- COSMOS-Near-Infrared Webb's Camera will scan a vast area of the sky—0.6 square degrees—with more than 200 hours of observation time (NIRCam). That's three full moons in size.
- With the Mid-Infrared Instrument, it will map a smaller region at the same time (MIRI).
"It's a huge swath of sky that's unique to the COSMOS-Webb mission. The majority of Webb projects go extremely deep, similar to pencil-beam surveys that examine small areas of sky "Caitlin Casey, an assistant professor at the University of Texas at Austin and the COSMOS-Webb program's co-leader, said.
We can look at big-scale features at the beginning of galaxy formation since we're covering such a wide region.
"We'll also search for some of the earliest galaxies, as well as trace the large-scale dark matter distribution of galaxies back to the beginning."
- Dark matter is invisible because it does not absorb, reflect, or emit light. Because of the impact it has on things that we can see, we know dark matter exists.
- With multi-band, high-resolution near-infrared imaging and an unprecedented 32,000 galaxies in the mid infrared, COSMOS-Webb will investigate half a million galaxies.
- This survey will be a major legacy dataset from Webb for scientists researching galaxies beyond the Milky Way, thanks to its fast public release of the data.
COSMOS started as a Hubble mission in 2002 to photograph a considerably bigger region of sky, about the size of ten full moons.
- The cooperation grew from there to encompass the majority of the world's main telescopes on Earth and in space.
- COSMOS is now a multi-wavelength survey that spans the whole electromagnetic spectrum from X-ray to radio.
- The COSMOS field is visible from observatories all around the globe because to its position in the sky.
- Because it is located on the celestial equator, it may be examined from both the northern and southern hemispheres, yielding a wealth of information.
"A lot of extragalactic scientists go to COSMOS to conduct their analyses because the data products are so widely available, and it covers such a large area of the sky," said Jeyhan Kartaltepe, assistant professor of physics and co-leader of the COSMOS-Webb program at Rochester Institute of Technology.
We're utilizing Webb to expand our coverage in the near-to mid-infrared portion of the spectrum, and therefore stretching out our horizon, or how far away we can see.
COSMOS-Webb will expand on past findings to achieve breakthroughs in three areas of research: changing our knowledge of the Reionization Era, searching for early, fully developed galaxies, and understanding how dark matter evolved with star content in galaxies.
To revolutionize our knowledge of the post-reionization period.
The cosmos was totally black soon after the big bang.
- Stars and galaxies, which provide light to the universe, had not yet formed.
- The cosmos was made out of a primordial soup of neutral hydrogen and helium atoms, as well as unseen dark matter.
- This period is known as the cosmic dark ages.
- The first stars and galaxies appeared after several hundred million years, providing energy to reionize the early cosmos.
- This energy broke apart the hydrogen atoms that made up the cosmos, charging them and bringing the cosmic dark ages to an end.
The Reionization Age is the name given to the new era in which the cosmos was filled with light.
- The primary aim of COSMOS-Webb is to study the reionization period, which occurred between 400,000 and 1 billion years after the big bang.
- Reionization most likely occurred in little bursts rather than all at once.
- COSMOS-Webb will search for bubbles that indicate where the early universe's initial pockets of reionization occurred.
The team wants to figure out how big these reionization bubbles are.
- "Hubble did a fantastic job of locating a few of these galaxies out to early periods," Casey said, "but we need many more galaxies to understand the reionization process." Scientists have no idea what type of galaxies ushered in the Reionization Era, whether they were large or low-mass systems.
- COSMOS-Webb will be able to locate extremely big, uncommon galaxies and study their distribution in large-scale structures, which will be a first.
So, do the galaxies that cause reionization live in a cosmic metropolis, or are they generally equally dispersed across space?
Only a large survey like COSMOS-Webb can assist scientists in answering this question.
Finding early, fully developed galaxies.
COSMOS-Webb will look for fully developed galaxies that stopped forming stars in the first 2 billion years after the big bang.
- Hubble has discovered a few of these galaxies, which call into question current theories about how the universe came to be.
- Scientists are baffled as to how these galaxies may contain ancient stars while not generating any new ones so early in the universe's existence.
- Many of these unusual galaxies will be discovered by the team using a big survey like COSMOS-Webb.
- They want to study these galaxies in depth in order to figure out how they might have developed so quickly and shut off star production so early.
Discovering how dark matter developed in relation to star content in galaxies.
COSMOS-Webb will provide scientists with information on how dark matter in galaxies has changed through time as the star composition of galaxies has changed.
- Galaxies are made up of two kinds of stuff: visible matter that we see in stars and other objects, and unseen dark matter that is frequently more massive than the galaxy and may surround it in a halo.
- In galaxy creation and evolution, these two types of matter are linked.
- However, there is currently little understanding of how the dark matter mass in galaxies' halos originated and how that dark matter influences galaxies' formation.
COSMOS-Webb will shed light on this process by enabling scientists to use "weak lensing" to directly detect these dark matter halos.
- Gravity from any kind of mass, whether dark or bright, may act as a lens, bending the light we see from faraway galaxies.
- Weak lensing alters the apparent form of background galaxies, allowing scientists to directly estimate the mass of the halo's dark matter when it's in front of other galaxies.
- "For the first time, we'll be able to measure the relationship between dark matter mass and luminous mass of galaxies back to the first 2 billion years of cosmic time," said team member Anton Koekemoer, a research astronomer at the Space Telescope Science Institute in Baltimore who helped design the program's observing strategy and is in charge of constructing all of the images from the project.
- "That's an important era for us to understand how galaxies' mass was initially set in place, and how dark matter halos drive it. And that, in turn, may help us comprehend galaxy formation in a more indirect way."
Data sharing with the community in a timely manner COSMOS-Webb is a Treasury initiative, and its goal is to generate datasets of long-term scientific relevance.
Treasury Programs aim to address a variety of scientific questions with a single, consistent dataset.
Data obtained via a Treasury Program typically does not have an exclusive access period, allowing other researchers to analyze it right away.
- "As a Treasury Program, you agree to release your data and data products to the community as soon as possible," Kartaltepe said.
- "We're going to create this community resource and make it publicly accessible so that other scientists may utilize it in their research."
- "A Treasury Program commits to making all of these scientific products publicly accessible so that anybody in the community, even at very tiny universities, may have the same, equal access to the data products and then simply conduct the work," Koekemoer said.
COSMOS-Webb is a General Observers program in Cycle 1.
- The General Observers programs were chosen via a competitive process utilizing a dual-anonymous review mechanism, similar to the one used to distribute Hubble time.
- When it launches in 2021, the James Webb Space Telescope will be the world's top space scientific observatory.
- Webb will explore beyond our solar system to distant planets orbiting other stars, as well as the enigmatic architecture and origins of our universe and our role in it.
- Webb is a NASA-led multinational project involving ESA (European Space Agency) and the Canadian Space Agency as partners.
courtesy www.nasa.com
~ Jai Krishna Ponnappan
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