NASA's Great Observatories Begin Deepest Ever Probe of the Universe
NASA's Hubble, Spitzer and Chandra space telescopes are teaming up to look
deeper into the universe than ever before. With a boost from natural "zoom
lenses" found in space, they should be able to uncover galaxies that are as much
as 100 times fainter than what these three great observatories typically can
see.
In an ambitious collaborative program called The Frontier Fields, astronomers
will make observations over the next three years of six massive galaxy clusters,
exploiting a natural phenomenon known as gravitational lensing, to learn not
only what is inside the clusters but also what is beyond them. The clusters are
among the most massive assemblages of matter known, and their gravitational
fields can be used to brighten and magnify more distant galaxies so they can be
observed.
"The Frontier Fields program is exactly what NASA's great observatories were
designed to do; working together to unravel the mysteries of the Universe" said
John Grunsfeld, associate administrator for NASA's Science Mission Directorate
in Washington. "Each observatory collects images using different wavelengths of
light with the result that we get a much deeper understanding of the underlying
physics of these celestial objects."
The first object they will view is Abell 2744, commonly known as Pandora's
Cluster. The giant galaxy cluster appears to be the result of a simultaneous
pile-up of at least four separate, smaller galaxy clusters that took place over
a span of 350 million years.
Astronomers anticipate these observations will reveal populations of galaxies
that existed when the universe was only a few hundred million years old, but
have not been seen before.
"The idea is to use nature's natural telescopes in combination with the great
observatories to look much deeper than before and find the most distant and
faint galaxies we can possibly see," said Jennifer Lotz, a principal
investigator with the Space Telescope Science Institute (STScI) in Baltimore,
Md.
Data from the Hubble and Spitzer space telescopes will be combined to measure
the galaxies' distances and masses more accurately than either observatory could
measure alone, demonstrating their synergy for such studies.
"We want to understand when and how the first stars and galaxies formed in
the universe, and each great observatory gives us a different piece of the
puzzle," said Peter Capak, the Spitzer principal investigator for the Frontier
Fields program. "Hubble tells you which galaxies to look at and how many stars
are being born in those systems. Spitzer tells you how old the galaxy is and how
many stars have formed."
The Chandra X-ray Observatory also will peer deep into the star fields. It
will image the clusters at X-ray wavelengths to help determine their mass and
measure their gravitational lensing power, and identify background galaxies
hosting supermassive black holes.
High-resolution Hubble data from the Frontier Fields program will be used to
trace the distribution of dark matter within the six massive foreground
clusters. Accounting for the bulk of the universe's mass, dark matter is the
underlying invisible scaffolding attached to galaxies.
Hubble and Spitzer have studied other deep fields with great success. The
Frontier Fields researchers anticipate a challenge because the distortion and
magnification caused by the gravitational lensing phenomenon will make it
difficult for them to understand the true properties of the background
galaxies.
For images and more information about The Frontier Fields, visit:
NASA
Guillermo Gonzalo Sánchez Achutegui
2 comentarios:
NASA's Great Observatories Begin Deepest Ever Probe of the Universe.
NASA's Great Observatories are teaming up to look deeper into the universe than ever before. With a boost from natural "zoom lenses" found in space, they should be able to uncover galaxies that are as much as 100 times fainter than what the Hubble, Spitzer, and Chandra space telescopes can typically see.
This ambitious collaborative program is called The Frontier Fields. Astronomers will spend the next three years peering at six massive clusters of galaxies. Researchers are interested not only as to what's inside the clusters, but also what's behind them. The gravitational fields of the clusters brighten and magnify distant background galaxies that are so faint they would otherwise be unobservable.
The clusters themselves are among the most massive assemblages of matter known.
Astronomers anticipate that these observations will reveal populations of never-before-seen galaxies that existed when the universe was only a few hundred million years old. The Hubble and Spitzer data will be combined to measure the galaxies' distances and masses more accurately than either observatory could measure alone, demonstrating the synergy of these Great Observatories for such studies. The Chandra X-ray Observatory will also peer deep into the fields, imaging them at X-ray wavelengths to help determine the masses and lensing power of the clusters, as well as identify background galaxies with massive black holes.
"The idea is to use nature's natural telescopes in combination with the Great Observatories to look much deeper than before and find the most distant and faint galaxies we can possibly see," said principal investigator Jennifer Lotz of the Space Telescope Science Institute (STScI) in Baltimore, Md.
"We want to understand when and how the first stars and galaxies formed in the universe, and each Great Observatory gives us a different piece of the puzzle. Hubble tells you which galaxies to look at and how many stars are being born in those systems. Spitzer tells you how old the galaxy is and how many stars have formed," said Peter Capak, the Spitzer principal investigator of the Frontier Fields program.
The high-resolution Hubble data from the Frontier Fields program will also be used to trace the distribution of dark matter within the foreground clusters. Accounting for the bulk of the universe's mass, dark matter is the underlying, invisible scaffolding attached to galaxies. "The apparent positions of those lensed galaxies then tell you what's happening with the cluster itself, where the dark matter is in that cluster," Lotz said. "We'll use that information to make a better model of the cluster to better understand its lensing power."
NASA
NASA's Great Observatories Begin Deepest Ever Probe of the Universe.
Be continue.......
The Hubble and Spitzer observations will be much more challenging for researchers than previous deep fields that have been studied by this powerful pair of observatories with great success. "With a deep image, you've got a direct image — what you see is what you get. But when we use a gravitational lens, background galaxies appear distorted and brighter," Lotz said. "In order to understand the true properties of a background galaxy, you have to understand how it is distorted and how it is magnified. This depends on the distribution of dark matter in the gravitational lens — the foreground cluster."
What's more, the galaxies seen in previous ultra-deep fields are just the most massive at those epochs. "They are the tip of the iceberg. If you want to see the galaxies that will turn into ones like our Milky Way, you have to go much fainter," Lotz said. Without using the big natural telescopes in space, astronomers would have to wait for the James Webb Space Telescope. In fact, the Frontier Fields offer a sneak peek of what the Webb telescope will routinely see anywhere it points in space, when it is launched in 2018.
The Hubble Frontier Fields initiative grew out of high-level discussions at STScI concerning what important, forward-looking science Hubble should be doing in upcoming years. Despite several deep field surveys, astronomers realized that a lot was still to be learned about the distant universe. And, such knowledge would help in planning the observing strategy for the Webb telescope.
To get a better assessment of whether doing more deep field observations was scientifically interesting or urgent, STScI chartered a "Hubble Deep Field Initiative" working group, which included U.S. and European astronomers who were expert users of the Great Observatories. The astronomers also considered synergies with other observatories, such as Spitzer, Chandra, and the new Atacama Large Millimeter Array. STScI Director Matt Mountain allocated his director's discretionary time to the program.
The first object to be looked at this month is called Pandora's Cluster (Abell 2744), which has been previously observed by all three Great Observatories but not to the depth of the new observations. The giant galaxy cluster appears to be the result of a simultaneous pile-up of at least four separate, smaller galaxy clusters that took place over a span of 350 million years.
Join several members of the Frontier Fields collaboration during the live Hubble Hangout event at 4:00pm (EDT) on Thursday, October 24 to discuss more on what's to come from these observations, how the clusters were chosen, and what we hope to learn from them. Visit: https://plus.google.com/u/0/events/cpl8pr6rjvls7en3c9ltrgelc80 .
NASA
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