Astronomy

Will the Sagittarius A* Black Hole eventually swallow the entire Galaxy?

Will the Sagittarius A* Black Hole eventually swallow the entire Galaxy?


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In one of his interviews, Sir Roger Penrose mentioned that when the Milky Way and the Andromeda galaxies eventually "collide" and merge into one, their super-massive black holes will also eventually merge. He further mentioned that the newly formed super-massive blackhole at the centre of the new galaxy will eventually "hoover out" all matter within the galaxy.

I recall reading that this is generally the case with super-massive black holes at the centers of galaxies: they will eventually "eat out" all matter within their galaxies.

Question: why don't the stars and other objects within the galaxies just keep rotating around these black-holes, like they do now? Why will they eventually be swallowed by the black hole's gravity pull?


Black holes do not suck in matter any more than stars and planets do: an object in orbit would remain in stable orbit if nothing perturbed it.

However, in the long run ($10^{19}$ years and more) interactions between stars will perturb their orbits, making many of them end up in the central black hole. An easy way of seeing this is to consider a random close encounter between two stars. They will change velocities, and potentially one will get a sufficiently high velocity to escape the galaxy - but the other one, by energy conservation, would be more tightly bound and orbit in a closer orbit. Eventually the galaxy "evaporates" through this kind of interaction, with heavier stars congregating near and eventually into the black hole and the lighter stars mostly expelled. (For all the mathematical details of this and related processes, see Binney & Tremaine's Galactic Dynamics).

Even if this did not happen, gravitational radiation makes a star orbiting something slowly lose angular momentum and spiral in, but this takes a far longer timescale.

Hence stars either fall in or are expelled over very long timescales.


Astronomers may have discovered a dozen black holes in the centre of our galaxy

Astronomers first noticed an enigmatic object, dubbed “Sagittarius A*”, at the very heart of our Milky Way galaxy in the 1960s – the earliest days of radio and infrared astronomy. But just how extraordinary this source was only became clear three decades later, when it was identified as a supermassive black hole with the mass of whopping four million suns.

Theory predicts that such supermassive black holes, which reside at the centre of most large galaxies, should be surrounded by a cluster of smaller black holes and other objects. But decades of searches have revealed nothing – until now. In a new paper, published in Nature, a team of researchers report the discovery of what seems to be about 13 black holes close to Sagittarius A*.

The discovery of Sagittarius A* was only possible thanks to the first generation of infrared imagers on the best ground-based observing sites in Hawaii and Chile. These could follow the motion of stars very close to the unseen object as they orbited around it.

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After a decade of observing, complete orbits of stars were mapped out in detail – allowing scientists to calculate the mass of Sagittarius A* with high accuracy.

This work had to be done by looking at infrared light. That’s because, at visual wavelengths, huge clouds of dust and gas obstruct our vision – we can only see about 10 per cent of the distance to the galactic centre in this way (Sagittarius A* is approximately 26,000 light years away).

Some infrared light, radio waves and X-rays, however, can penetrate the obstacles in the galaxy to reach our detectors on Earth.

How supermassive black holes grow so large is still controversial. Sagittarius A* is actually fairly small – distant objects of a billion solar masses have been found.

One possible explanation is that they are created as galaxies merge or interact, trapping their central supermassive black holes into orbits about each other and eventually merging into an even bigger supermassive black hole.

We know that active star formation is going on in the region of our galactic centre. This will naturally produce copious neutron stars (very dense stars) and black holes, which can form close “binary systems” in which a normal star and a neutron star or a black hole orbit each other.

As the normal star evolves, its matter can get sucked up by the black hole or fall onto the neutron star – reaching extremely high temperatures. This makes the system emit X-rays, which we can detect.

It is not surprising then that the unique and very high resolution of the space-based Chandra X-ray Observatory has detected hundreds of X-ray sources in and around our galactic centre. You can view some superb images of these objects here.

X-ray puzzle

The new study has used Chandra data to investigate X-ray sources close to Sagittarius A*. Over the last 12 years, Chandra has observed Sagittarius A* many times – adding up to a huge total of two weeks of exposure time.

By combining all these data, and concentrating on the area close to the centre, the team discovered diffuse X-ray emission and about 100 distinct X-ray sources within 13 light years of Sagittarius A*, 26 of which are contained within just three light years of it.

So what are these mysterious sources? It’s been known for some time that thousands of unresolved binary systems involving a normal star and a magnetised white dwarf (a star that has exhausted its fuel, just like our sun will do in a few billion years) can create diffuse X-ray emission.

Unlike the X-rays from binary systems involving neutron stars, these are relatively weak. However, there are millions of white dwarfs in the galaxy.

The team also looked at the ratio of hard to soft X-rays (basically just the higher energy light compared to the lower energy rays) to show that the central X-ray sources closest to Sagittarius A* are likely either from binary systems (involving neutron stars or black holes), or from “millisecond pulsars”, which are highly magnetised rotating neutron stars that emit a beam of electromagnetic radiation.

Both types (binary systems and pulsars) undergo occasional X-ray outbursts, but their properties differ. The neutron stars outburst regularly, but Chandra’s observations show that none of the sources near Sagittarius A* have done so – meaning we can rule these out. Pulsars, however, could account for about half of the sources – they are very steady and quiet.

But that means that the remaining half at least must be binary systems involving black holes – a class that have much rarer outbursts (usually many decades between them) and properties generally similar to those seen in the study. The team suggests there could be hundreds of such black hole binaries at the centre of our galaxy and thousands of black holes without a companion star.

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Future observations are needed to confirm this finding. It can be particularly tricky to distinguish between binary systems involving quiescent (minimally accreting) black holes and millisecond pulsars. But the better the technology gets, the more accurately will we be able to do this.

If these really are black holes, it is extremely exciting – showing that we are on the right track in understanding how supermassive black holes impact the behaviour of stars around them. It might even be important for future observations using gravitational waves (ripples in the fabric of space itself). If one of these new sources merge into Sagittarius A*, this should give rise to gravitational waves that we can detect.

Clearly, we still have a lot to learn about our own galaxy. In a way that’s very exciting there may be many more black holes in the region left to discover.

Phil Charles is a professor of astrophysics at the University of Southampton. T his article was first published in The Conversation


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What is Sagittarius a*? (with pictures)

Sagittarius A* (pronounced "A-star") is a region in the center of our galaxy, approximately as wide as the orbit of Pluto, containing 3.7 million solar masses of material. Located near the galactic center, Sagittarius A* is suspected by astronomers to be a supermassive black hole, serving as the center of gravity for the entire galaxy. Sagittarius A* is closely orbited by at least a dozen stars, the trajectories of which have been used to estimate its mass. It may even be orbited by the first observed intermediate-mass black hole, GCIRS 13E, which is estimated at 1,300 solar masses.

As the mass of a black hole increases, the radius of its event horizon increases at a linear rate, but the density decreases as the cube of the radius. So, while black holes like Sagittarius A* are very massive, when you count the huge area of the event horizon, estimated at 6.25 light-hours (45 AU) or about 4.2 billion miles, the average density of the hole is no greater than that of air! Stellar-mass black holes have much greater densities behind their event horizon.

Sagittarius A* is located approximately 25,000 light years away, or half a galactic radius, at the galaxy's center. It probably formed early on in the galaxy's history. We observe supermassive black holes like Sagittarius A* in the process of being formed in other, very distant galaxies. These phenomena are called quasars and blazars.

Because the central singularity in a supermassive black hole is located so far from the event horizon, an astronaut falling into it would not experience spaghettification until deep inside the hole. The inside of a black hole would be a strange place -- with light orbiting the hole at a rapid rate, you would be constantly treated to a repetitive blur of objects in its grasp. Light from the outside would first look like only a hemisphere, with darkness all behind, then the hemisphere would get progressively smaller, becoming a little circle and eventually a point. Falling into a black hole would not be fun!

Michael is a longtime contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

Michael is a longtime contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.


Every Point Is A Supermassive Black Hole In Most Revealing Astronomical Study Ever

This map made from the LOFAR survey shows supermassive black holes clustered in the Universe. The . [+] total map spans 740 square degrees, or about 2% of the sky, and has revealed over 25,000 black holes thus far.

LOFAR LBA Sky Survey / ASTRON

A large enough mass in a compact volume inevitably forms a black hole.

Both inside and outside the event horizon of a Schwarzschild black hole, space flows like either a . [+] moving walkway or a waterfall, depending on how you want to visualize it. At the event horizon, even if you ran (or swam) at the speed of light, there would be no overcoming the flow of spacetime, which drags you into the singularity at the center. Outside the event horizon, though, other forces (like electromagnetism) can frequently overcome the pull of gravity, causing even infalling matter to escape.

Andrew Hamilton / JILA / University of Colorado

In 1964, we observationally detected our first one: Cygnus X-1.

The X-ray emitter Cygnus X-1, in the constellation of Cygnus, as imaged by a balloon-borne . [+] telescope. The balloon was launched for the High Energy Replicated Optics (HERO) project on May 23, 2001, reaching an altitude of 39 km.

NASA / Marshall Space Flight Center

Black holes emit no light, but numerous physical processes can still reveal them.

Cygnus X-1, at left, is an X-ray emitting black hole orbiting another star. Located

6,000 . [+] light-years away in the constellation of Cygnus, it was the first black hole candidate, later confirmed to be a black hole, observed in the Universe: in 1964.

Optical: DSS Illustration: NASA

Matter infalling into a black hole’s vicinity forms accretion disks.

A black hole feeding off of an accretion disk. It's friction, heating, and the interplay of charged . [+] particles in motion creating electromagnetic forces that can funnel mass inside the event horizon. But at no point does a black hole exert a sucking force just a standard, run-of-the-mill gravitational one, while much of the external matter gets accelerated and ejected.

Mark Garlick (University of Warwick)

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Once sufficiently heated, that matter emits X-ray light.

When a black hole accretes matter, it grows an accretion disk and will increase its mass as matter . [+] gets funneled into the event horizon. The matter outside of the event horizon won't all fall in much of it will be accelerated and eventually ejected, emitting radiation of various wavelengths in the process.

NASA/ESA Hubble Space Telescope collaboration

These “X-ray binaries” revealed humanity’s first black holes.

The first black holes were detected electromagnetically: as X-ray binaries. The purple points show . [+] X-ray black hole binaries the yellow show X-ray emitting neutron stars. The black hole and neutron star mergers detected from gravitational waves, since 2015 only, are shown in blue and orange, respectively.

LIGO/VIrgo/Northwestern Univ./Frank Elavsky

Supermassive black holes also produce X-rays.

The supermassive black hole at the center of our galaxy, Sagittarius A*, flares brightly in X-rays . [+] whenever matter is devoured. In longer wavelengths of light, from infrared to radio, we can see the individual stars in this innermost portion of the galaxy. Gas emissions indicated a supermassive black hole of

2.7 million solar masses, but improved observations of stars at the galactic center revealed a mass of

4 million solar masses instead.

X-ray: NASA/UMass/D.Wang et al., IR: NASA/STScI

NASA’s Chandra discovered thousands in its ultra-deep images.

A map of the 7 million second exposure of the Chandra Deep Field-South. This region shows hundreds . [+] of supermassive black holes, each one in a galaxy far beyond our own. The GOODS-South field, a Hubble project, was chosen to be centered on this original image. Its view of supermassive black holes is only one incredible application of the NASA's Chandra X-ray observatory.

NASA/CXC/B. Luo et al., 2017, ApJS, 228, 2

Energetic black hole outflows create positrons: the electron’s antimatter counterpart.

On either side of the plane of the Milky Way, enormous gamma-ray bubbles are being blown. The energy . [+] spectrum seen indicates that positrons had been generated recently in great amounts, creating bubbles some 50,000 light-years in total extent. Both gamma-rays and X-rays are generated, powered by the 4 million solar mass engine at the center of the Milky Way.

NASA/Goddard Space Flight Center

These ejecta generate “Fermi bubbles” around galactic centers, including our own.

In the main image, our galaxy's antimatter jets are illustrated, blowing 'Fermi bubbles' in the halo . [+] of gas surrounding our galaxy. In the small, inset image, actual Fermi data shows the gamma-ray emissions resulting from this process, with the red-and-blueshifts indicating that one jet is more pointed towards us and the other an equivalent amount away from us.

David A. Aguilar (main) NASA/GSFC/Fermi (inset)

Additionally, gravitational waves reveal inspiraling and merging black holes.

Two black holes of approximately equal mass, when they inspiral and merge, will exhibit the . [+] gravitational wave signal (in amplitude and frequency) shown at the bottom of the animation. The gravitational wave signal will spread out in all three dimensions at the speed of light, where it can be detected from billions of light-years away by a sufficient gravitational wave detector.

N. Fischer, H. Pfeiffer, A. Buonanno (Max Planck Institute for Gravitational Physics), Simulating eXtreme Spacetimes (SXS) Collaboration

But radio studies uncover black holes most abundantly.

This X-ray/radio composite shows a supermassive black hole actively feeding within a distant galaxy. . [+] From a great distance, the X-ray emission will often be invisible, but the radio emissions can frequently be seen from active galaxies across the cosmos.

X-ray: NASA/CXC/KIPAC/N. Werner et al Radio: NSF/NRAO/AUI/W. Cotton

Infalling matter around black holes commonly produces radio waves.

This is an artist's impression of a distant quasar 3C 279. The bipolar jets are a common feature, . [+] but it's extremely uncommon for such a jet to be pointed directly at us. When that occurs, we have a Blazar, now confirmed to be a source of both high-energy cosmic rays and the ultra-high-energy neutrinos we've been seeing for years.

This explains the origin of quasars: QUAsi-StellAr Radio Sources.

The Pictor A galaxy has a supermassive black hole at its center, and material falling onto the black . [+] hole is driving an enormous beam, or jet, of particles at nearly the speed of light into intergalactic space. This composite image contains X-ray data obtained by Chandra at various times over 15 years (blue) and radio data from the Australia Telescope Compact Array (red). By studying the details of the structure seen in both X-rays and radio waves, scientists might better understand the nature of quasars.

X-ray: NASA/CXC/Univ of Hertford

Supermassive, active black holes emit tremendously powerful radio signals.

When hot gas actively falls onto the central black hole within a galaxy, a quasar can be produced. . [+] The radiation can span across the electromagnetic spectrum, but the proper radio survey can reveal even X-ray quiet quasars that an X-ray survey would miss.

NASA/CXC/Penn. State/G. Yang et al and NASA/CXC/ICE/M. Mezcua et al. Optical: NASA/STScI Illustration: NASA/CXC/A. Jubett

Installation Manager Derek McKay checks some of the 96 radio antennae installed for the new European . [+] Low Frequency Array (LOFAR) telescope. The LOFAR array spans the entire continent of Europe, and is humanity's most sensitive radio telescope in its particular frequency band. (Chris Ison/PA Images via Getty Images)

PA Images via Getty Images

The survey area and the detected signals (in surface brightness) of the LOFAR telescope. Covering . [+] 740 square degrees on the sky, or 1.85% of what's out there, the team identified 25,247 individual sources, where each one in a supermassive black hole. Note how they reveal the clustering of the Universe.

F. de Gasperin et al. (2021), arXiv:2102.09238

When quasar orientation can be observed and identified, it is found that they align in a non-random . [+] way with the large-scale cosmic web that defines the Universe's structure. The LOFAR data is the best-ever quasar data taken of such a significant region of the Universe, and has revealed clustering effects even beyond this one.

LOFAR will eventually survey the entire northern hemisphere, expecting

600,000+ identifiable black holes.

Thus far, LOFAR has only observed where the yellow dots are indicated: about 2% of the total sky. By . [+] the end of 2022, it will have observed everywhere the red dots are located, and its eventual goal is to survey the entire northern hemisphere. At its current sensitivity, LOFAR can expect a total yield of over 600,000 quasars.

F. de Gasperin et al. (2021), arXiv:2102.09238

Observationally abundant, black holes aren’t purely theoretical anymore.

This 20-year time-lapse of stars near the center of our galaxy comes from the ESO, published in . [+] 2018. Note how the resolution and sensitivity of the features sharpen and improve towards the end, and how the central stars all orbit an invisible point: our galaxy's central black hole, matching the predictions of Einstein's general relativity.

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less smile more.


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2013 September 6
The Quiet Sagittarius A*
Credit: X-ray - NASA / CXC / Q. Daniel Wang (UMASS) et al., IR - NASA/STScI

Explanation: Hot gas is hard to swallow. At least that seems to be true for the supermassive black hole at the center of our Milky Way Galaxy. Known as source Sagittarius A*, the Milky Way's black hole is centered in this infrared (red and yellow hues) and X-ray (blue) composite. Based on data from an extensive campaign of observations by the orbiting Chandra X-ray telescope, the diffuse emission surrounding the black hole is seen in the close-up inset, the inset field spanning about 1/2 light-year across the galactic center some 26,000 light-years away. Astronomers have found that the X-ray emission originates in hot gas drawn from the winds of massive young stars in the region. The Chandra data indicate that only about 1% or less of the gas within the black hole's gravitational influence ever reaches the event horizon, losing enough heat and angular momentum to fall into the black hole, while the rest of the gas escapes in an outflow. The result explains why the Milky Way's black hole is so quiet, much fainter than might be expected in energetic X-rays. It likely holds for most supermassive black holes in galaxies in the nearby Universe.


A Pulsar Sheds Light on the Situation

In April 2013, SWIFT found a pulsar within half a light year from A*. Further research revealed that it was a magnetar which was emitting highly polarized x-ray and radio pulses. These waves are highly susceptible to changes in magnetic fields and will have their orientation (vertical or horizontal movement) altered based on the strength of the magnetic field. In fact, Faraday rotation, which causes the pulses to twist as they travel though a 𠇌harged gas that is within a magnetic field,” did occur on the pulses. Based on the magnetar’s position and ours, the pulses travel through gas that is 150 light years from A* and by measuring that twist in the pulses, the magnetic field was able to be measured at that distance and thus a conjecture about the field near A* can be made (NRAO, Cowen).

Heino Falcke of Radboud University Nijmegen in the Netherlands used the SWIFT data and observations from the Effelsberg Radio Observatory to do just this. Based off the polarization, he found the magnetic field to be about 2.6 milligauss at 150 light years from A*. The field near A* should be several hundred gauss, based off this (Cowen). So what does all this talk about magnetic field have to do with how A* consumes matter?

As matter travels in the accretion disk, it can increase its angular momentum and sometimes escape the clutches of the black hole. But it has been found that small magnetic fields can create a type of friction which will steal angular momentum and thus cause the matter to fall back to the accretion disk as gravity overcomes it. But if you have a large enough magnetic field, it may trap the matter and cause it to never fall into the black hole. It almost acts like a dam, impeding its ability to travel near the black hole. This could be the mechanism at play at A* and explain its odd behavior (Cowen).

Radio/Millimeter Wavelength View

The Black Hole At the Center of the Galaxy

It is possible that this magnetic energy fluctuates because evidence exists for A*&aposs past activity being much higher than it currently it. Malca Chavel from the Paris Dident University look at data from Chandra from 1999 through 2011 and found x-ray echoes in the interstellar gas 300 light years from the galactic center. They imply that A* was over a million times more active in the past. And in 2012 Harvard University scientists discovered a gamma ray structure that went 25,000 light years from both poles of the galactic center. It could be a sign of consumption as recently as 100,000 years ago. Another possible sign is about 1,000 light-years across our galactic center: Not many young stars exist. Scientists cut through the dust using the infrared portion of the spectrum to see that Cepheid variables, which are 10-300 million years old, are lacking in that region of space, according to the August 2, 2016 issue of Monthly Notices of the Royal Astronomical Society. If A* chowed down, then not many new stars would be present, but why so few so far outside A*&aposs grasp? (Scharf 37, Powell 62, Wenz 12).

The orbits of the objects close to A*

Indeed, the star situation presents many issues because they are in a region where star formation should be difficult if not impossible because of wild gravitational and magnetic effects. Stars have been found with signatures indicating they formed 3-6 million years ago which is too young to be plausible. One theory says it could be older stars that had their surfaces stripped in a collision with another star, heating it up to look like a younger star. However, to accomplish this around A* should destroy the stars or lose too much angular momentum and fall into A*. Another possibility is that the dust around A* allows for star formation as it was hit by these fluctuations but this requires a high density cloud to survive A* (Dvorak).


7 Replies to &ldquoWill Our Black Hole Eat the Milky Way?&rdquo

Fraser……..rather than regurgitate preposterous concepts that have no scientific basis perhaps you might consider some theories that have observational validity and are experimentally verifiable.
My first objection is your use of the term “black hole”. This massive and enormously powerful structure found at the center of our galaxy (and almost every other galaxy) is neither black nor can it be a “hole” in anything. By who, when and why was this term chosen. The latest radio telescope data has revealed these galactic center structures emit multiple plasma jets, EM radiation (gamma and x ray) as well as visible light. These findings required the addition of the “accretion disc” since they invalidated the model that said the gravity was so powerful even light could not escape. I wonder how the accretion disc (or whatever) sits above the gravitational forces with impunity. I’m sure there is a mathematical explanation which, thank goodness, obviates the need for any radio telescope data.
But what is really curious is the recent documentation of massive, and I mean colossal, magnetic fields surrounding these galactic centers. This finding is being basically ignored by astrophysicists and cosmologists when the evidence should be the topic of every scientific conversation regarding these galactic centers (“black holes”).
It’s important to ignore these magnetic fields, the electric currents that cause them and the underlying plasma morphology of which they consist.

btraymd……..rather than regurgitate preposterous concepts that have no scientific basis perhaps you might consider some theories that have observational validity and are experimentally verifiable… for instance, I don’t know, the known behavior of the EM force in the first place?

Seriously, how are you going to ignore the known rules covering the electromagnetic force AND THEN propose that that same force is responsible for what we see in the cosmos in exact conflict with those same rules? Even if we DIDN’T have Relativity to fall back on, that’s a special kind of illogical.

Not to be boring but there are some observations which make common sense and have an important experimentally verified foundation.
First, gravity is too weak to be the cause of galaxy formation. The mathematical creation of dark matter to salvage this idea has no scientific, experimental or observational support.
Everyone should revisit the basic research performed by plasma physicist Anthony Peratt at Los Alamos National Labs in the 80’s. His work has been confirmed by many plasma physic labs and his findings have not been refuted to this day. They have just been ridiculed and ignored. Sound familiar.
This Nobel Prize winning (eventually) work by Peratt showed the formation of spiral galaxies using only electric current, plasma and magnetic fields. Black holes and dark matter were not required. These formations also had the necessary velocities to maintain galactic structure.
If ever the principle of Occam’s Razor needs to be applied, this is it.
For the G.U.T., think electromagnetism, not gravity. It’s Faraday, Alvfens, Birkeland and Tesla ( and many others such as Velikosky, Jurrgens, Scott and Thornhill)……not Einstein.

Point by point, then:
“First, gravity is too weak to be the cause of galaxy formation.”
1) “Straw Man:” for the most part, gravity just holds the collection together.
“The… creation of dark matter … has no scientific, experimental or observational support.”
2) FALSE: observation itself is what requires “dark matter” exist, the only mystery being what it’s made of.
“The basic research… by Peratt showed the formation of spiral galaxies using only electric current, plasma and magnetic fields.”
3) FALSE: the experiments were done in the 1950’s by Winston H. Bostick, producing galaxy-shaped structures Peratt’s work was an immense extrapolation of those results.
“If ever the principle of Occam’s Razor needs to be applied, this is it.”
4) TRUE. Since we know the EM force loses/gains strength too fast w/distance to do anything but collapse or explode the galactic structures we see, it cannot be the main force responsible for maintaining them.
“For the G.U.T., think electromagnetism, not gravity. It’s [a list of folks]…not Einstein.”
5) UNKNOWN, however Einstein’s work is at least validated by observation & testing, unlike the Electric/Plasma Universe concept. In addition (& ALSO unlike the E.U. idea), it does not require ignoring the laws of electromagnetism (of all things!) in order to work.

If interstellar space was filled with plasma to allow conduction, as maintained, the braking effect on stellar motion would be greater than observed.
Another problem, unless there is a source of energy from fusion, fission, radioactive decay or stored,
all plasmas will eventually condense due to the effects of relative motion, and the net positive charge of the ionized atom recapturing the electron(s).
The conservation of energy is maintained by the emission of light or other frequencies of EM radiation depending on the shell transition by the electron.
This effect outweighs the photoelectric effect.
The example of the fluorescent tube can not be used as a counter argument because the source of energy is electricity generated from stored sunlight (coal).
To the contrary. When the electrical energy source is removed, any mercury plasma condenses to mercury vapour, and the light goes out.

To my knowledge, not all galaxies have supermassive black holes within them. Specifically, small irregular galaxies (like the Large and Small Magellanic Clouds) do not. This is consistent with my personal theory that most, if not all, irregular galaxies are remnants of galactic collisions and cannibalism.

If I’m mistaken – for instance, if there are supermassive black holes associated with the Magellanic Clouds – I’d like someone to let me know, and give me a reference so I can learn more.



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Milky Way's Giant Black Hole to Eat Space Cloud in 2013

The colossal black hole at the center of our Milky Way galaxy will soon to get a big, tasty meal, astronomers say.

A humongous gas cloud is on a collision course for the Milky Way's core — the home of Sagittarius A* (pronounced "Sagittarius A-star"), which scientists suspect is a supermassive black hole with the mass of 4 million suns.

When the huge gas cloud arrives in the vicinity, which it will appear to us to do in mid-2013, it will surely be swallowed up by the hungry black hole, scientists say.

Astrophysicist Stefan Gillessen of the Max Planck Institute for Extraterrestrial Physics in Munich, Germany, has been observing the Milky Way's center for about 20 years. So far, he's seen only two stars come as close to Sagittarius A* as the cloud will.

"They passed unharmed, but this time will be different: the gas cloud will be completely ripped apart by the tidal forces of the black hole," Gillessen said in a statement.

The cloud is due to pass within about 36 light-hours (about 25 billion miles, or 40 billion kilometers) of the black hole. Its speed, which is now more than 5 million mph (8 million km per hour), has nearly doubled in the last seven years as it approaches its doom. It has already started to shred, and is likely to break up completely before it hits the black hole.

While black holes themselves are impossible to see — they are objects whose gravitational pull is so strong, even light cannot escape — astronomers can watch what happens when matter falls into one. The areas around some active supermassive black holes are so bright, in fact, that they are visible across the universe.

Scientists are looking forward to the rare chance to see something fall into our own galaxy's black hole. As it falls nearer and nearer, the cloud is expected to heat up and release bright X-ray radiation that should be visible from Earth.

The collision-bound cloud was discovered by a team of astronomers led by Reinhard Genzel at the European Southern Observatory.


Star reveals magnetic field around Milky Way's monster black hole

A strange, pulsing star has revealed a powerful magnetic field around the giant black hole at the heart of Earth’s Milky Way galaxy, scientists say.

The finding may help shed light on how the galaxy's supermassive black hole devours matter around it and spits out powerful jets of superhot matter, the researchers added.

The center of virtually every large galaxy is suspected to host a supermassive black hole with a mass that can range from millions to billions of times the mass of the sun. Astronomers think the Milky Way's core is home to the monster black hole called Sagittarius A* — pronounced "Sagittarius A-star" — that is about 4 million times the mass of Earth's sun. [No Escape: How Black Holes Work (Infographic)]

Scientists want to learn more about how black holes distort the universe around them, hoping to see if the leading theory regarding black holes, Einstein's theory of general relativity, holds up or if new concepts might be necessary. One way to see how black holes warp space and time is by looking at clocks near them. Cosmic versions of clocks are known as pulsars — rapidly spinning neutron stars that regularly give off pulses of radio waves.

Pulsar tells the tale
Astronomers have been searching for pulsars near Sagittarius A* for the past 20 years.

Earlier this year, NASA's NuSTAR telescope helped confirm the existence of such a pulsar apparently less than half a light-year away from the black hole, one that pulsates radio signals every 3.76 seconds. Scientists quickly analyzed the pulsar using the Effelsberg Radio Observatory of the Max Planck Institute for Radio Astronomy in Bonn, Germany.

"On our first attempt, the pulsar was not clearly visible, but some pulsars are stubborn and require a few observations to be detected," said study lead author Ralph Eatough, an astrophysicist at the Max Planck Institute. "The second time we looked, the pulsar had become very active in the radio band and was very bright. I could hardly believe that we had finally detected a pulsar in the galactic center." [See a video of the pulsar and zoom in on the Milky Way's black hole]

Additional observations were performed in parallel and subsequently with other radio telescopes around the world. "We were too excited to sleep in between observations," said study co-author Evan Keane from the Jodrell Bank Observatory in England.

The newfound pulsar, named PSR J1745-2900, belongs to a rare kind of pulsars known as magnetars, which only make up about 1 out of every 500 pulsars found to date. Magnetars possess extremely powerful magnetic fields, ones about 1,000 times stronger than the magnetic fields of ordinary neutron stars, or 100 trillion times the Earth's magnetic field.

The radio pulses from magnetars are highly polarized, meaning these signals oscillate along one plane in space. This fact helped the researchers detect a magnetic field surrounding Sagittarius A*.

Black hole magnetic field revealed
Black holes swallow their surroundings, mainly hot ionized gas, in a process of accretion. Magnetic fields threading within this accretion flow can influence how this infalling gas is structured and behaves.

"The magnetic field we measure around the black hole can regulate the amount of matter the black hole eats and could even cause it to spit matter out in so-called jets," Eatough told Space.com. "These measurements are therefore of great importance in understanding how supermassive black holes feed, a process that can affect galaxy formation and evolution."

As radio signals traverse the magnetized gas around black holes, the way they are polarized gets twisted depending on the strength of the magnetic fields. By analyzing radio waves from the magnetar, the researchers discovered a relatively strong, large-scale magnetic field pervades the area surrounding Sagittarius A*.

In the area around the pulsar, the magnetic field is about 100 times weaker than Earth's magnetic field. However, "the field very close to the black hole should be much stronger — a few hundred times the Earth's magnetic field," Eatough said.

If the magnetic field generated by the infalling gas is accreted down to the event horizon of the black hole — its point of no return — that could help explain the radio and X-ray glow long associated with Sagittarius A*, researchers added.

"It is amazing how much information we can extract from this single object," said study co-author Adam Deller at the Netherlands Institute for Radio Astronomy in Dwingeloo.

Astronomers predict there should be thousands of pulsars around the center of the Milky Way. Despite that, PSR J1745-2900 is the first pulsar discovered there. "Astronomers have searched for decades for a pulsar around the central black hole in our galaxy, without success. This discovery is an enormous breakthrough, but it remains a mystery why it has taken so long to find a pulsar there," said study co-author Heino Falcke at Radboud Universiteit Nijmegen in the Netherlands.

"It could be the environment is very dense and patchy, making it difficult to see other pulsars," Eatough added.

The researchers cannot test the leading theory regarding black holes using PSR J1745-2900 — they cannot measure the way it warps space-time accurately enough, since the pulsar is slightly too far away from Sagittarius A* and, being relatively young, its spin is too variable. The researchers suggest pulsars that are closer to the black hole and are older with less variable spins could help test the theory.

"If there is a young pulsar, there should also be many older ones. We just have to find them," said study co-author Michael Kramer, director of the Max Planck Institute for Radio Astronomy.

The scientists detailed their findings online Wednesdayin the journal Nature.


Watch the video: Gefräßiges Schwarzes Loch: Warum wird Sagittarius A aktiver? (November 2022).