- 3999 - GALAXIES - Farthest galaxies? A monstrous cluster of galaxies lurks at the heart of this Hubble Space Telescope image. The Hubble Space Telescope gazes into the lair of a monstrous cluster of galaxies located nine billion light-years away in the constellation Draco.
------------------------- 3999 - GALAXIES - Farthest galaxies?
- This
celestial beast can be seen by the ripples around it. It is so titanic that the
ripples aren't traveling the surface of an ocean or lake but rather are
distortions in the fabric of space-time itself.
-
- This
particular galaxy cluster, known as “eMACS J1823.1+7822”, is one of five
selected for observation by Hubble astronomers to determine the strength of
this "warping" effect, which was first predicted by Albert Einstein's
theory of general relativity.
-
- The 1915
theory, which is occasionally called Einstein's geometric theory of gravity,
predicts that, as bowling balls placed on a trampoline create a depression,
objects with mass cause the very fabric of space-time to warp. This curvature
gives rise to the force of gravity. And the greater the mass of a cosmic
object, the more extreme the warping of space it causes.
-
- Light
travels across the universe in straight lines, but when it encounters a warp
caused by a truly massive object, its path is curved. When the warping object
is between Earth and a background object, it can curve light in such a way that
the apparent position of the background object is shifted.
-
- But when the
intermediate or "lensing object" is truly massive, like a monstrous
cluster of galaxies, light from the
background source takes a different amount of time to reach Earth depending on
how close it passes to this natural cosmic lens.
-
- This
effect, called “gravitational lensing”, can make single objects appear at
multiple points in the sky, often in stunning arrangements called Einstein
rings and Einstein crosses. It can also cause background objects to appear
amplified in the sky, a powerful effect that astronomers use to observe distant
and early faint galaxies.
-
- The
distortion caused by massive clusters can also help astronomers study
mysterious dark matter, which accounts for around 85% of the mass in the
universe but is invisible because it does not interact with electromagnetic
radiation. Because dark matter does interact gravitationally, however, the
lensing of light by a galaxy or galactic cluster can help researchers map the
distribution of dark matter.
-
- In the new Hubble
image this collection of elliptical galaxies, acts as a gravitational lens. The
cluster warps the shape of the galaxies around it, giving them a slightly
elongated shape, turning some into arcs and others into bright streaks.
-
- Observing
objects at different wavelengths allows for a more complete picture of the
structure. Observations can reveal the
composition and behavior of an object that would be hidden in visible light
alone.
-
- When
combined with the use of clusters like eMACS J1823.1+7822, gravitational
lensing allows this to be done for some of the universe's earliest galaxies. So
powerful observatories like Hubble and the James Webb Space Telescope can probe
conditions found shortly after the Big Bang and the very birth of the universe.
-
May 13, 2023 GALAXIES - Farthest galaxies? 3999
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--------------------- --- Saturday, May 13, 2023
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