Simulated map of missing satellite galaxies could answer dark matter puzzle

Simulated map of missing satellite galaxies could answer dark matter puzzle
This image, captured by the Very Large Array, shows the atomic hydrogen distribution of the Whirlpool Galaxy. The “X” marks the dwarf companion satellite. Dynamical simulations can recover its location and mass. Credit: Chakrabarti et al. 2011

A ripple in the outskirts of the Milky Way—and a hunch—led Rochester Institute of Technology astrophysicist Sukanya Chakrabarti to a previously undetected dwarf galaxy hidden under a veil of dark matter. Now Chakrabarti is refining her technique to uncover dwarf galaxies and understand dark matter by simulating the evolutionary histories of galactic disks, rich in atomic hydrogen, and their satellite populations.

Chakrabarti's study on these overlapping regions found in spiral , like the Milky Way, is funded by a three-year $325,053 grant from the National Science Foundation. Her research seeks to solve an astrophysical conundrum dubbed "the missing satellites problem," in which theoretical simulations that predict an abundance of satellite galaxies are unsupported by observational data.

Earlier this year, Chakrabarti, assistant professor of physics in RIT's School of Physics and Astronomy, validated her prediction of a previously unseen satellite galaxy located close to the plane of the Milky Way. In her new study, Chakrabarti and Andy Lipnicky, a Ph.D. student in RIT's astrophysical sciences and technology program, will create the first "mock" map and catalogue of satellite populations from analyzing extended disks.

"We will produce models that are consistent with both the atomic hydrogen and stellar data of our galaxy, which displays large ripples in the outskirts, a prominent warp and vertical waves in the galactic disk," Chakrabarti said.

Chakrabarti's goal of gaining an understanding of the distribution of combines her method with gravitational lensing. She will analyze the ripples in the atomic hydrogen map and results from gravitational lensing—a technique that uses the bending of light to weigh distant galaxies and reconstruct the dark-matter background.

"Comparing and contrasting results from both methods might improve the statistics of detecting dark-matter dominated ," Chakrabarti said.


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Mapping dark matter from galactic ripples

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Jul 24, 2015
A ripple in the outskirts of the Milky Way—and a hunch—led Rochester Institute of Technology astrophysicist Sukanya Chakrabarti to a previously undetected dwarf galaxy hidden under a veil of dark matter.


Another conundrum of the dark matter models. How does dark matter, which is invisible, hide a dwarf galaxy?

Jul 24, 2015
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Jul 24, 2015
When they say that she validated her prediction does that mean that they actually made a physical, optical observation of the dwarf galaxy? They text is not clear on this point.

Jul 24, 2015
How do you measure the amount of bending in the light when you do not have a straight-line view from another reference position to say what the apparent position of more distant objects "should be"?

This is bad science.

Jul 24, 2015
Odd isn't it, everything that has anything to do with dark matter is "Simulated", they even need to admit in the title.

Jul 24, 2015
How do you measure the amount of bending in the light when you do not have a straight-line view from another reference position to say what the apparent position of more distant objects "should be"?

This is bad science.


Why you "Simulate" it of course......Massey sitting beneath his telescope over there in England has an entire cadre of astro-physicists sitting at desks adding blue toned air-brushing to pictures he takes of galaxies. Amazing isn't it? Turning astro-physicists into artists.


Jul 25, 2015
How do you measure the amount of bending in the light when you do not have a straight-line view from another reference position to say what the apparent position of more distant objects "should be"?

This is bad science.

Just because you don't know how they do it?
This is a bad post.


You have to know what "straight" is before you can measure "curvature".

They have no point of reference, when looking at distant objects farther away than Parallax can be used for (which it cant be used for galaxies), so there is no way to define what "straight" ought to be.

You are far too trusting of the establishment.

If great minds like Newton or Einstein had acted the way you do, always following the establishment, then we would never have had the progress we have experienced in physics and mathematics.

Jul 25, 2015
More on other causes of the "Dark Matter" phenomenon.

There could be any number of "Brown Dwarfs" and Rogue planets which may be as much as...well...13.7 billion years old, and which may have cooled to equilibrium with the CMB during that time. These objects would be undetectable with existing radio telescopes and infrared telescopes, and may even be undetectable with the James Webb or even that other telescope (the next generation one already planned after James Webb is finished, forgot the name).

How many Brown Dwarfs and rogue planets are ejected from galaxies and are in intergalactic space? Remember, Brown Dwarfs are like 10 to 100 times less massive than "Stars", so accelerating them to escape velocity via ordinary "momentum assist" ejections would be 10 to 100 times easier than for ordinary stars....there are ordinary stars and even some globular clusters observed to be on hyperbolic orbits of the Milky Way, meaning they acheived escape velocity...

Jul 25, 2015
Now if Stars and even whole Globulars can be ejected from the galaxy, then it stands to reason that objects 100 times lighter, such as Brown Dwarfs, or objects millions of times lighter, such as most planets and planetesmals, can be ejected 10, 100, even a million times more easily.

Once kicked out into inter-galactic space, away from stars, perhaps while early galaxies were forming or during galaxy collisions, these objects would tend to cool to the same temperature as the CMB, and would become, for all practical purposes, invisible....being "invisible" but interacting gravitationally, they would appear to be "inter-galactic Dark Matter".

Statistically, brown dwarfs should form about 100 times more often than stars, and planets and planetesmals should form about 300,000 to 1.5 million times as often as stars, yet we generally see planets and dwarf planets around stars numbering only about 4 to 10, with perhaps 20 total "Planetary" objects in our solary system.

Jul 25, 2015
Where did all these statistically predicted planets and planetesmals go?

Based on the geometry of a disk, and the geometry of a sphere (for sake of argument) slightly more of the Brown Dwarfs and Rogue Planets should be ejected from the galaxy than the number which get thrown deeper into the galaxy. A cube circumscribed about a sphere so that each face is a plane tangent to a sphere will show you why...there is much more than a 50% volume for any given point on the sphere which is outside the sphere than there is inside the sphere, because the plane represents a 50% probability, but the surface of the sphere is much smaller in total than the plane. Any trajectory above the surface is a possible escape route for an object at or above escape velocity.

This ratio actually changes based on the size of the sphere and cube used, because larger spheres actually have lower "curvature" than do smaller spheres.

Jul 25, 2015
More scrambling to 'find' dark matter/energy. Canadian scientist paper on molecular hydrogen: http://www.newton...dex.html
Quote"We also showed that the presence of large amounts of the hard-to-detect molecular hydrogen in interstellar space could provide an alternative explanation to the Big Bang theory, by explaining the observed redshift as a result of the delayed propagation of light through space, caused by the collision of photons with interstellar matter."

Jul 25, 2015
Which is to say, something like a Dwarf Galaxy inscribed inside a Cube has higher curvature (in Euclidean Geometry) than does a larger galaxy inscribed inside a Cube.

This higher curvature is important, because it means even fewer trajectories lead back into the dwarf galaxy than does lead back into the larger galaxy. This means that not only does a dwarf galaxy grow slower due to lower gravity, but it also grows slower simply due to an effect that relative curvature of a sphere increases as radius decreases.

This curvature to which I am referring is the calculus based calculation of curvature, and NOT the gravitational curvature of space-time due to relativity. These are two unrelated effects which nevertheless effect reality in every case.

An easy example is that the surface of Pluto or the Moon(Luna) are both more curved than the surface of the Earth, so relative to a cube fit to their size, a lower percentage of trajectories lead back into the object.

Jul 25, 2015
Katesisco:

This is possible, because entropy would suggest that each collision of the photons would cause a slight "downshift" in the energy level of the next escaping photon, as some of the energy would be absorbed by the atom in different ways besides the electron orbital method. Some would increase the temperature of the nucleus, and for assymetric collsions some would influence rotation of the molecule, etc, so the emitted photon is weaker, "redder" than the original.

This is also not the same thing as "Tired C" arguments, but it nevertheless would produce the same observational effect.

There is one problem though, the radiation observed would pick up hydrogen spectral lines so that it would be characterized by slightly stronger hydrogen spectral line signature than the actual contents of the star or other object which created the original radiation.

The "observations" of the universe have "most of the ordinary mass" of the universe as hydrogen anyway.

Jul 25, 2015
The effect you describe could, in some cases, cause scientists to over-estimate the distance to some objects (red is associated with farther and faster), over-estimate their age (red is usually associated with older), and over-estimate their hydrogen content (due to increased signature of hydrogen spectral lines).

It is a reasonable theory, but there are some problems.

Quasars produced from galaxy mergers, (of which both the Milky Way and Andromeda have no-doubt gone through one or more Quasar phases each,) give off so much intense radiation and plasma winds that they can, in some cases, heat the inter-galactic media to thousands and even millions of degrees. Moreover, positive ions in the plasma state have difficulty cooling without the electron orbital shift mechanism which normally cools atoms.

By my estimation, though "charge" is preserved, standard stellar fusion models suggest electron number may be lower than proton number due to positron-electron annihilation.

Jul 25, 2015
The afore mentioned positron-electron annihilation in Stars occurs during the proton-proton chain, when one of a pair of neutrons is created, in order to preserve charge and mass, a positron is released....this would immediatelly annihilate with a nearby electron and release gamma rays.

So what's the deal?

Nucleotide antimatter (anti-protons) are very rare in our universe, and they are not produced in the reactions believed to take place inside of stars.

While the total charge of the universe remains the same, what has happened is an electron was annihilated. But electrons are ejected from stars due to radiation pressure, and hang around somewhere near the Heliopause which differs in distance based on the Star's mass and luminosity.

Positve ions ejected from a galaxy are nowhere near the electrons they need to neutralize themselves, and they are too hot to receive an electron anyway, which is a problem for the hypothesis you propose in cases where Quasar activity existed.

Jul 25, 2015
The electromagnetic force is, on average, over 20 orders of magnitude greater per unit mass than is the gravitational force, so you would expect that these ions should be attracted massively back towards the electrons in the interstellar media within galaxies, at least once the quasar winds have died down, and assuming even more electrons were not either blown deeper into inter-galactic space or trapped in black holes, etc..

So for your hypothesis to actually hold and become a "theory" you would need to discover a cooling mechanism for the inter-galactic plasmas to cool to a temperature where molecular chemistry can occur again within a cosmic time period short enough to allow the "optical illusion" you describe to become plausible.

Jul 25, 2015
.........c'mon $02, you stated over in that other thread that the calculation for DM is "simple". Put up your calculations like Einstein did for gravitational lensing, calculations which in & of themselves disproved the existence of DM twenty years before Zwicky even hypothesized it.......but you probably don't comprehend what I'm getting at do you?

Jul 25, 2015
You do not know how they do it. So find out and then criticise. You are far too trusting about your own capability and you lack responsibility, always blaming others.


What about your capability for doing a "simple calculation" for proving the existence of all this vaunted DM that makes up 75-90% of the Universe. Maybe you don't present the "simple calculation" because you are far too distrusting of your math skills to risk proving the neophyte you really are.

The "simple calculation" please..........and don't exceed Partial DE's or I won't be able to follow you.

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