- 4379
- BIGGEST BLACKHOLE
- and the first stars? What's the biggest black hole in the
universe, and is there a limit to how big black holes can get? It turns out that there is a theoretical
limit to the size of black holes which are celestial objects so massive that even light cannot
escape them. And the largest directly observed black hole with a confirmed mass
is right around this limit.
----------------------------- 4379 - BIGGEST BLACKHOLE - and the first stars?
- This monster blackhole is named “TON 618”,
weighs roughly 40,000,000,000 solar
masses. TON 618 has a radius of over 1,000 astronomical units (AU), which means
that if the black hole was placed in the center of the solar system, by the
time you reached Pluto, you would be less than 5% of the way from the center of
the black hole to its edge.
-
- TON 618 sits about 18.2 billion light-years
away from Earth. In the night sky, it sits
on the border between the constellations Canes Venatici and Coma
Berenices. Astronomers first spotted it
in a 1957 survey but didn’t realize what it was. They first thought it was a
faint blue star, but observations a decade later revealed that the astronomers
had glimpsed intense radiation from the material falling into the giant black
hole.
-
- TON 618 powers a quasar, one of the
brightest objects in the entire universe with the illuminating power of 140
trillion suns. Quasars draw light from the gravitational energy of the central
black hole. Material around the black hole falls in, and as it does so it
compresses and heats up, releasing enormous amounts of radiation. While
individual events like the most powerful supernovas can briefly outshine
quasars, they only last a few weeks. In contrast, quasars can shine for
millions of years.
-
-
However, quasars are so far away that they only appear as faint spots of visible light in even the most powerful telescopes, and astronomers first detected them by their powerful radio emissions.
-
- Quasars are actually supermassive black
holes that are feeding. Supermassive black holes become enormous through a
combination of merging with other black holes and by constantly feeding on
surrounding material.
-
- This feeding rate is what sets the limit on
the size of a black hole. These cosmic vacuum cleaners can only consume so much
material in a given amount of time. As material falls in, it heats up and
releases radiation (creating a quasar), but that radiation heats the material
itself, preventing it from quickly falling into the black hole. This
self-regulation prevents black holes from growing too quickly.
-
- Astronomers can estimate a maximum mass for
a black hole by taking that feeding rate and multiplying it by the known age of
the universe, giving an estimated maximum mass of around 50 billion solar
masses.
-
- There may be other, more exotic, ways to
create large black holes, such as from the direct collapse of large clumps of
dark matter in the early universe. So it's still possible that there are even
more massive black holes out there.
-
- A newly discovered mystery object could be
the heaviest neutron star ever seen, the smallest. The unknown object, discovered 40,000
light-years away inside a dense globule of stars named “NGC 1851”, was detected
through the rapid flashes of its orbiting companion. This rotating neutron star known as a
“pulsar” that sweeps out a beam of light once every 6 milliseconds.
-
- This pulsar falls within "mass
gap" between black holes and neutron stars, meaning it could be either
one. A pulsar-black hole system will
be an important target for testing theories of gravity and a heavy neutron star
will provide new insights in nuclear physics at very high densities.
-
- Both black holes and neutron stars are
stellar corpses, left behind after massive stars end their lives in violent
explosions called supernovas. Despite being born the same way the two types of
objects can have vastly different masses.
Supermassive black holes can weigh as much as billions of suns, while
neutron stars rarely get heavier than about three solar masses. But the
lightest black holes and the heaviest neutron stars can look very similar from
far away.
-
- For most of astronomy's history, scientists
could only spot neutron stars as heavy as twice the mass of the sun and black
holes as light as five solar masses, leaving everything in between a mystery.
The gap between the two, known as the “mass gap”, was finally crossed in 2019,
when the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected
space-time ripples indicative of a light black hole or heavy neutron star
falling somewhere between the two.
-
- To spot the new object, astronomers used
the MeerKAT radio telescope in South Africa to scan the NGC 1851 globular
cluster. The cluster is a crowded blob
of stars so tightly packed that the cosmic furnaces may sometimes knock one
another from their orbits and even collide.
-
- Faint radio pulses repeating 170 times a
second drew the astronomers' attention to a pulsar, and by observing the subtle
changes to its highly regular "ticks," the scientists mapped out its
orbital motion. This revealed that the pulsar was in a binary system, orbiting
an object of roughly 3.9 solar masses whis is in the middle of the mass gap.
-
- The object could be the most massive neutron
star known, the lightest black hole, or some yet-to-be-characterized exotic
star. Uncovering the true nature of the
companion will be a turning point in our understanding of neutron stars, black
holes, and whatever else might be lurking in the black hole mass gap.
-
- That would be the lightest but what about
the biggest black hole in the universe.
Is there a limit to how big black holes can get? There is a theoretical limit to the size of
black holes which are celestial objects
so massive that even light cannot escape them.
The largest directly observed black hole with a confirmed mass is right
around this limit.
-
- Which came first: Black holes or
galaxies? Black holes not only existed
at the dawn of time, they birthed new stars and supercharged galaxy formation. This observation is challenging classical
understanding that they formed after the first stars and galaxies emerged.
Instead, black holes might have dramatically accelerated the birth of new stars
during the first 50 million years of the universe, a fleeting period within its
13.8 billion-year history.
-
- We know monster black holes exist at the
center of galaxies near our Milky Way, but the big surprise now is that they
were present at the beginning of the universe as well and were almost like
building blocks or seeds for early galaxies.
They really boosted everything, like gigantic amplifiers of star
formation, which is a whole turnaround of what we thought possible.
-
- Distant galaxies from the very early
universe appear much brighter than scientists predicted and reveal unusually
high numbers of young stars and supermassive black holes.
-
- Conventional wisdom holds that black holes
formed after the collapse of supermassive stars and that galaxies formed after
the first stars lit up the dark early universe. But this analysis suggests that
black holes and galaxies coexisted and influenced each other's fate during the
first 100 million years. If the entire history of the universe were a 12-month
calendar, those years would be like the first days of January.
-
- The black hole outflows crushed gas clouds,
turning them into stars and greatly accelerating the rate of star
formation. Otherwise, it's very hard to
understand where these bright galaxies came from because they're typically
smaller in the early universe. Why on earth should they be making stars so
rapidly?
-
- Black holes are regions in space where
gravity is so strong that nothing can escape their pull, not even light.
Because of this force, they generate powerful magnetic fields that make violent
storms, ejecting turbulent plasma and ultimately acting like enormous particle
accelerators. This process is likely why James Webb's detectors have spotted
more of these black holes and bright galaxies than scientists anticipated.
-
- These enormous winds coming from the black
holes crush nearby gas clouds and turned them into stars. That's the missing
link that explains why these first galaxies are so much brighter than we
expected."
-
- During the first phase, high-speed outflows
from black holes accelerated star formation, and then, in a second phase, the
outflows slowed down. A few hundred million years after the big bang, gas
clouds collapsed because of supermassive black hole magnetic storms, and new
stars were born at a rate far exceeding that observed billions of years later
in normal galaxies. The creation of stars slowed down because these powerful
outflows transitioned into a state of energy conservation, reducing the gas available to form stars in
galaxies.
-
- We thought that in the beginning, galaxies
formed when a giant gas cloud collapsed.
The big surprise is that there was a seed in the middle of that cloud, a
big black hole, and that helped rapidly turn the inner part of that cloud into
stars at a rate much greater than we ever expected. And so the first galaxies
are incredibly bright.
-
- The big question is, what were our
beginnings? The sun is one star in 100 billion in the Milky Way galaxy, and
there's a massive black hole sitting in the middle, too. What's the connection
between the two? Webb is unlocking
secrets of primeval galaxy
-
- Looking deep into space and time, two teams
using the NASA/ESA/CSA James Webb Space Telescope have studied the
exceptionally luminous galaxy GN-z11, which existed when our 13.8
billion-year-old universe was only about 430 million years old.
-
- The exceptionally luminous galaxy existed
when the universe was just a tiny fraction of its current age. It is one of the
youngest and most distant galaxies ever observed, and it is also one of the
most enigmatic. Why is it so bright?
-
- They found the first clear evidence that
the galaxy is hosting a central, supermassive black hole that is rapidly
accreting matter. Their finding makes this the most distant active supermassive
black hole spotted to date. They found
extremely dense gas that is common in the vicinity of supermassive black holes
accreting gas. These were the first
clear signatures that GN-z11 is hosting a black hole that is gobbling matter.
-
- They found indications of ionized chemical
elements typically observed near accreting supermassive black holes.
Additionally, they discovered that the galaxy is expelling a very powerful
wind. Such high-velocity winds are typically driven by processes associated
with vigorously accreting supermassive black holes.
-
- Webb's NIRCam (Near-Infrared Camera)
revealed an extended component, tracing the host galaxy, and a central, compact
source whose colors are consistent with those of an accretion disk surrounding
a black hole. Together, this evidence
shows that GN-z11 hosts a two-million-solar-mass, supermassive black hole in a
very active phase of consuming matter, which is why it's so luminous.
-
- They also found a gaseous clump of helium in
the halo surrounding GN-z11. The fact
that they don't see anything else beyond helium suggests that this clump must
be fairly pristine. This is something that was expected by theory and
simulations in the vicinity of particularly massive galaxies from these
epochs. There should be pockets of
pristine gas surviving in the halo, and these may collapse and form Population
III star clusters.
-
- Finding the so far unseen Population III
stars—the first generation of stars formed almost entirely from hydrogen and
helium—is one of the most important goals of modern astrophysics. These stars
are expected to be very massive, very luminous, and very hot. Their signature
would be the presence of ionized helium and the absence of chemical elements
heavier than helium.
-
- The formation of the first stars and
galaxies marks a fundamental shift in cosmic history, during which the universe
evolved from a dark and relatively simple state into the highly structured and
complex environment we see today.
-
-
March 5, 2024 BIGGEST
BLACKHOLE - and the first stars? 4379
------------------------------------------------------------------------------------------
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Pass it on to whomever is interested. --------
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------ “Jim Detrick” -----------
--------------------- --- Thursday, March 7, 2024
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