- 4096 - EARLIEST GALAXIES - more than expected? As astronomers push our views of the Universe further back in time, their telescopes keep uncovering surprises.
---------------- 4096 - EARLIEST GALAXIES - more than expected?
- The earliest galaxies already existed and
was assembling itself some 570 million years after the Big Bang. The James Webb
Space Telescope (JWST) caught a glimpse of it and studied its black hole. It
also took data about two other black holes as they were when the Universe was
about a billion years old.
-
- These galaxy and black hole discoveries are
part of a special observing program, called the Cosmic Evolution Early Release
Science (CEERS) Survey. The idea is to get detailed images and spectra of
early, distant objects in infrared and mid-infrared light. -
-
- Objects in the very early universe shine in
ultraviolet and visible light. However, by the time their light reaches us,
it’s “stretched” into the infrared regime. Since infrared also can penetrate
through dusty regions, it gives the added advantage of seeing objects that
otherwise would be hidden.
-
- Finding black holes in the early universe
in early galaxies opens up our understanding of that time in cosmic history. It
is shortly after the Big Bang. This newly found CEERS galaxy and its active
supermassive black hole surprised astronomers. CEERS 1019 existed at a time
when the first galaxies were forming. So, they should be small and relatively
featureless, right? And, if they have black holes at that early epoch, those
should be relatively low-mass. Right?
-
- It turns out that those black holes ARE
lower-mass. But, at least one of them is still larger than it should be. How do
we know this? JWST can study both early galaxies and their black holes. With Webb, not only can we see black holes
and galaxies at extreme distances, we can now start to accurately measure them.
That’s the tremendous power of this telescope.
-
- The black hole, within galaxy CEERS 1019,
existed just over 570 million years after the big bang and is far less massive
than other black holes previously found in the early universe.
-
- The galaxy itself appears as three bright
clumps without a disk. So, it’s still
assembling itself and cranking out new stars as it builds its structure. We’re not used to seeing so much structure in
images at these distances. A galaxy
merger could be partly responsible for fueling the activity in this galaxy’s
black hole, and that could also lead to increased star formation.
-
- That infant supermassive black hole is
busily ingesting gas and turns out to have 9 million solar masses. That’s less
than some black holes of its era but still larger than expected. It exists so
early in history that it seems to have formed very shortly after the Universe
began.
-
- While the infrared view shows us the
structure of the galaxy, the spectral lines -
reveal other characteristics.
Spectra can pinpoint high-energy outflow speeds and temperatures. In the
case of CEERS 1019, the spectroscope captures both the black hole and its host
galaxy. Its data reveal the black hole’s appetite for gas as well as the
star-formation rate.
-
- The epoch of reionization was when light
from the first stars could travel through the infant universe. At this time,
galaxies began assembling, as did black holes.
The
epoch of reionization was when light from the first stars could travel through
the infant universe. At this time, galaxies began assembling, as did black
holes.
- The Epoch of Reionization is a point in cosmic history when light began to
travel freely across the expanding universe. That light came from the first
stars and ionized the gas between stars and galaxies. It also appears that
galaxies began assembling during this time as well.
-
- The survey data covers the build-up of stars
mass, the morphological changes in the galaxies as a result, as well as the
growth of those early black holes. Studying this period is key to tracing a
timeline of the Universe’s origins and evolution through the buildup and
transformation of those earliest galaxies.
-
- This is one of the key aims of the JWST,
which is just finishing its first full year of observing the infrared universe.
-
- For More Information see Review 4057 - “EARLIEST GALAXIES
- was this the beginning?”
-
-
July 14, 2023 4091
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Tuesday, July 18, 2023 ---------------------------------
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