Astronomers chart invisible dark matter outside the Milky Way
Image: NASA/ESA/JPL-Caltech/Conroy et. al
A mysterious wake of stars, stirred up by a small galaxy that is set to collide with the Milky Way, could be about to unlock the mysteries of dark matter.
The trail of stars, located outside the star-flecked spiral arms of the Milky Way’s central disk in a region called the galactic halo, is being carried along in the cosmic slipstream of a dwarf galaxy in orbit around the Milky Way, according to a new sky map created by astronomers.
The galaxy, called the Large Magellanic Cloud (LMC), is orbiting some 130,000 light-years away from Earth and stirring up the wake of cosmic material behind it. At first glance, the LMC’s trail appears to consist solely of stars, but the researchers know that the stars are just along for the ride. They are suspended inside a far larger, completely invisible presence.
Astronomers are interested in this ripple in space because they think it could be made up of dark matter — the mysterious non-luminous substance making up the vast majority of matter in the universe. Predictions say that dark matter, invisible and interacting with the matter we can see only through gravity, should be everywhere in the galactic halo.
“We think this wake is made up of dark matter, and it drags stars along with it, which is how we can detect it,” study co-author Nicolás Garavito-Camargo, a University Arizona doctoral student, said in a statement.
Dark matter’s gravitational influence can be observed throughout the universe: It is our galaxy’s vital scaffolding, glueing stars and planets to it so they don’t fly off as the galaxy spins. Yet, what exactly dark matter is, or how it behaves, remains one of astronomy’s greatest mysteries. The researchers are hoping that by studying the wake, they will be able to study the dark matter they believe makes up the vast majority of it.
If the wake’s stars are like leaves floating on a dark matter pond, the way that the leaves are disturbed by a boat (in this case, the LMC) can tell us a lot about the pond itself.
“You can imagine that the wake behind a boat will be different if the boat is sailing through water or through honey,” said lead author Charlie Conroy, a professor of astronomy at Harvard University. “In this case, the properties of the wake are determined by which dark matter theory we apply.”
The group has used their new map and the position of the wake to confirm a theoretical model, created by another group of researchers, about just how dark matter should be distributed across the galactic halo; they are now running tests to see which of the theories about dark matter best fits the wake’s shape and location.
The map, made with data from NASA and European Space Agency (ESA) telescopes, also provides some vital insights into our home galaxy’s violent future. As the LMC orbits the Milky Way, the gravitational tug from the dark matter in the Milky Way’s galactic halo is slowing it down, sending the LMC into smaller and smaller orbits. The LMC will continue to be reeled closer to the Milky Way until, in about 2 billion years, the two will collide.
The merging of two galaxies is a surprisingly common event throughout the universe. The Milky Way likely merged with a small galaxy 8 billion years ago, and galaxy mergers are a key reason for the growth of all large galaxies.
“This robbing of a smaller galaxy’s energy is not only why the LMC is merging with the Milky Way, but also why all galaxy mergers happen,” study co-author Rohan Naidu, said a graduate student at Harvard University. “The wake in our map is a really neat confirmation that our basic picture for how galaxies merge is on point.”
The researchers published their findings April 21 in the journal Nature.
See more here: livescience.com
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Charles HIgley
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I wish them luck as they pretend Dark Matter exists. There is no reason for Dark Matter at all when you recognize that the Big Bang Theory is based on soap bubble technology. Recognize the electric nature of the universe and there is no need for Dark Matter, Force, or Energy and no Big Bang at all. Big Bang Theory cannot begin to explain the filamentous structure of the universe, but an electromagnetic universe explains everything, without fantasizing new forces and matter. Black holes also becomes extraneous as they do not exist, as evidenced by there being about nine models for black holes. Why nine? None of them work.
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Allan Shelton
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The anti BBT people were/are treated the same way as anti AGW people.
The AGW people followed the MO as was used against the anti BBT people.
You all know what they are……………..
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Robert Beatty
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If you assume the Newtonian constant G is the same throughout the universe, then dark matter makes some sense, as do other similar theories.
However, if G varies leading to regions of higher and lower gravity forces in the universe, then you have, in my opinion, a more likely answer to why galaxies and spiral arms move the way they do.
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Herb Rose
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Hi Robert,
You know that I believe that gravity is the result of the energy associated with matter not its mass, so I don’t believe in G. Here’s a question for you. If the inertial mass (resistance to movement) of two objects is equal to their gravitational mass (impetus to create movement) how can they ever create motion?
Herb
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Robert Beatty
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Herb,
“If the inertial mass (resistance to movement) of two objects is equal to their gravitational mass (impetus to create movement) how can they ever create motion?”
If the two masses are in orbit, say. They retain motion through their initial impetus. They do not create motion of their own accord.
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Herb Rose
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Hi Robert,
You’re ducking the question. What was it that created the initial orbital motion if it wasn’t the attraction between masses?
Herb
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Robert Beatty
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Herb,
That’s like asking what makes magnets stick together.
I have published my thoughts on where gravitons come from, which you have no doubt seen. Gravitons originate at black holes providing a central focus for all gravity fields.It appears that matter operating within a gravity field, accepts a load of gravitons, which provides the property of mutual attraction to the atomic structure of matter. So if you are saying energy is associated with matter, that energy is in the form of gravitons – the more matter you have the greater the associated graviton load, and coincidently, the higher the mass.
Unlike magnets, the graviton attraction property does not appear to have a repulsion component.
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Herb Rose
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Hi Robert,
Instead of creating a graviton with no repelling force what if you say the attractive force of energy (gravity and magnetism) is stronger than the electric forces produced by matter. That is why a neutron, not in a nucleus, moving through a magnetic field splits into a proton, electron, and gamma ray in ten minutes.
The energy force is attracted to positive matter and is able to displace negative matter and it is this interaction that forms the atom, holds the nucleus together, and radiates an attractive force in the form of gravity. The forces of matter (electric) and the force of energy have opposite behavior. When opposite poles of magnets come together they created a larger radiated magnetic force. When opposite electric charges come together the radiated electric fields decline. When similar poles of magnets are forced towards each other the radiated magnetic field decline, while when similar charges are forced together the radiated electric field increases. Because the force of energy is stronger than the force of matter there a residual radiated force you identify as gravitons. As the attractive force pulls object together the combined radiated attractive force (energy) increase and the force between the object decreases. At the same time the attractive force is becoming radiated the repelling force between the object’s electron fields increases until it matches the attractive force. Any disturbance to this equilibrium between electric and magnetic fields will produce an oscillation (light) that will be transmitted through the fields.
No need to create a new particle with unique (not binary) properties
Herb.
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Robert Beatty
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Herb,
I note you prefer electromagnetism, which you have previously referred to as the e-thing, rather than gravity. Unfortunately EM strength decays faster than gravity. When applied to interstellar type distances – the subject of this article, which refers to the LMC conundrum, that represents a serious shortcoming.
The magnetic strength is also an inherent property of the rotating atoms with the direction of rotation determining the field direction. This is unlikely to be a general interstellar property.
Your free neutron discussion is interesting, but does not cover how neutron stars achieve stability. I think this happens due to the stabilising influence of the Positronium particle.
The ‘residual gravity’ you refer to appears to be a dominate force in space at several black hole locations, as evidenced from astronomical observation.
I note you do not believe in G. To my mind a variable G value explains ‘dark matter’ and ‘flat rotation’ curves. It can also be used to calculate the distance to the barycentre of a gravity field. In the case of Earth, the value for G indicates our solar system’s barycentre is 3,343 light years away.
Good luck with promoting your e-thing theory.
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