Astrophyicists draw most comprehensive map of the universe

April 27, 2015
A slice through the 3D map of the nearby universe. Our Milky Way galaxy is in the centre, marked by a cross.  The map spans nearly two billion light years from side to side. Regions with many galaxies are shown in white or red, whereas regions with fewer galaxies are dark blue. 

Astrophysicists have created a 3D map of the universe that spans nearly two billion light years and is the most complete picture of our cosmic neighbourhood to date.

The spherical map of galaxy superclusters will lead to a greater understanding of how matter is distributed in the universe and provide key insights into , one of physics' greatest mysteries.

Professor Mike Hudson, Jonathan Carrick and Stephen Turnbull, of the Department of Physics and Astronomy at the University of Waterloo, and Guilhem Lavaux the Institute d'Astrophysique de Paris of the Centre national de la recherche scientifique of France, created the map. Professor Hudson is also an affiliate member of the Perimeter Institute for Theoretical Physics.

"The galaxy distribution isn't uniform and has no pattern. It has peaks and valleys much like a mountain range. This is what we expect if the large-scale structure originates from quantum fluctuations in the early universe," said Hudson, also associate dean of science, computing.

The map appears online in the peer-review journal, Monthly Notices of the Royal Astronomical Society, one of the world's leading primary research journals for astronomy and astrophysics.

The lighter blue and white areas on the map represent greater concentrations of galaxies. The red area is the supercluster called the Shapley Concentration, the largest collection of galaxies in the nearby universe. Unexplored areas appear in medium blue.

This first video shows the density field smoothed with a Gaussian window of 10 Mpc/h:

Knowing the location and motion of matter in the universe will help astrophysicists predict the universe's expansion and identify where and how much dark matter exists.

Scientists have observed that galaxies move differently because the universe's expansion is not even. These differences are called peculiar velocities. Our own Milky Way galaxy and its neighbour Andromeda are moving with a speed of 2 million kilometres per hour.

Previous models haven't fully accounted for this observed motion. Hudson and his team are interested in discovering what structures are responsible for the peculiar velocities.

This second video shows the density field smoothed with a Gaussian window of 4 Mpc/h:

These deviations in the motion of galaxies are a valuable tool to determine the distribution of matter and dark matter on the largest scales.

Dark matter accounts for a large majority of the mass content in the . It is a hypothesized form of matter particle that does not reflect or emit light and as a result it can't be seen or measured directly. The existence and properties of dark matter can only be inferred indirectly through its gravitational effects on and light.

"A better understanding of dark matter is central to understanding the formation of galaxies and the structures they live in, such as galaxy clusters, superclusters and voids," said Hudson.

The next step will involve getting more detailed samples of peculiar velocities to enhance the map, in collaboration with researchers in Australia.

Explore further: Astronomers measure weight of galaxies, expansion of universe

More information: Monthly Notices of the Royal Astronomical Society, mnras.oxfordjournals.org/content/450/1/317.abstract . arxiv.org/abs/1504.04627

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Itar_Pejo
4 / 5 (5) Apr 27, 2015
"Our own Milky Way galaxy and its neighbor Andromeda are moving with a speed of 2 million kilometers per hour. "

Relative to what, other galaxies, some 'fixed' point in space or something?
MandoZink
4.4 / 5 (7) Apr 27, 2015
Doppler shift can be calculated by observing radiation from every direction. The result shows a particular vector and velocity that our Local Group of galaxies is moving in relative to the Cosmic Microwave Background radiation.
Itar_Pejo
3.7 / 5 (3) Apr 27, 2015
Thanks MandoZink
Mike_Massen
1 / 5 (5) Apr 27, 2015
MandoZink states & seems to claim
The result shows a particular vector and velocity that our Local Group of galaxies is moving in relative to the Cosmic Microwave Background radiation
Beg pardon ?

CMBR is everywhere as if we are the center of a ball & expanding still, looking out at the surface at all directions & see CMBR relatively distant equally with remarkable consistency & only minor fluctuation, just where do you think this vector points as current understanding re 'inflation' is there is no actual start point to move outwards from in the first place ?

Do u think we are the center of a ball of expansion or the conventional physics re overall inflation ie All points came from the one big bang singularity etc ?

ie.
Do you imagine moving towards area from the 'center' towards an 'outer' region more than another & how the heck do we delineate this in any sort of absolute sense - it You implied something akin to absolute re direction ?

Please clarify ?
shavera
5 / 5 (5) Apr 27, 2015
CMBR *is* everywhere, and it's at a very uniform "temperature." Except that in one direction in the sky it's warmer (blue-shifted) and one direction it's colder (red-shifted). These blue and red shifts give a "dipole moment" to the temperature, and that, in turn, tells us our velocity relative to the CMBR 'rest frame'

ie, early in the universe, the relatively local plasma has some 'rest' frame, where the motion of ions average out to zero. This frame is what we observe in the CMBR (when it froze out to a gas), and we have motion relative to that rest frame.

A common misconception about the big bang is that it was a spherical "explosion." It was not. It was a rapid expansion *throughout* all of space. The CMBR we see is plasma that was distant from us turning transparent into a gas a long time ago. There's no center to it (as a distant observer would see "our" plasma just turning into gas now, just the same)
billpress11
3 / 5 (2) Apr 27, 2015
http://abyss.uore...und.html

Quote from link:
" The velocity of the satellite about the Earth, the Earth about the Sun, the Sun about the Galaxy, and the Galaxy through the universe actually makes the temperature seem slightly hotter (by about one part in 1,000) in the direction of motion rather than away from it. The magnitude of this effect--the so-called dipole anisotropy--allows astronomers to determine that the Local Group of galaxies is moving at a speed of about 600 km/sec in a direction that is 45 from the direction of the Virgo cluster of galaxies. Such motion is not measured relative to the galaxies themselves (the Virgo galaxies have an average velocity of recession of about 1,000 km/sec with respect to the Milky Way system) but relative to a local frame of reference in which the cosmic microwave background radiation would appear as a perfect Planck spectrum with a single radiation temperature."
RichManJoe
5 / 5 (1) Apr 27, 2015
However, if the doppler is with respect to the CMBR, and the average of the CMBR reference would appear to be the same everywhere in the universe, then, do all galaxies have the same doppler shift WRT the CMBR?

billpress11
3 / 5 (2) Apr 27, 2015
However, if the doppler is with respect to the CMBR, and the average of the CMBR reference would appear to be the same everywhere in the universe, then, do all galaxies have the same doppler shift WRT the CMBR?


I would think they would have similar shifts plus or minus in every direction relative to the CMBR. But then how that would fit in with the BB theory, I would be at a lost to explain. I'll let someone else take a stab at that.
SuperThunderRocketJockey
3.7 / 5 (3) Apr 27, 2015
The white plus sign marks the only place in the universe where you can get coffee.
Whydening Gyre
5 / 5 (2) Apr 27, 2015
The white plus sign marks the only place in the universe where you can get coffee.

Not to mention - a donut or croissant to go with it...
Wait - is this the one at the end of the Universe?
Mike_Massen
1 / 5 (2) Apr 28, 2015
shavera stated
This frame is what we observe in the CMBR (when it froze out to a gas), and we have motion relative to that rest frame
Immense assumption here is that temperature indicate a direction of movement not minor variance in expansion...

Surely We ONLY have our Point Of View & cannot correlate/differentiate with that of other galaxies moving differently so we can be sure its "only" a temp diff view from doppler & NOT a quantum type artifact of expansion variance ?

shavera added
A common misconception about the big bang is that it was a spherical "explosion." It was not. It was a rapid expansion *throughout* all of space
Yes correct, asked Mondozink to clarify overall predicated on his claim.

shavera claims
The CMBR we see is plasma that was distant from us turning transparent into a gas a long time ago
Beg Pardon ?
Surely you meant to say it "was" plasma NOT 'is' now, its ONLY light (from cold gas) at microwave, ie radiative emission ?

cont
Mike_Massen
1 / 5 (1) Apr 28, 2015
@shavera
In other words.

How can we be sure an observed Doppler shift in this microwave frequency is really representative of movement in a particular direction wrt the so called CMBR 'rest frame' and NOT the possibility the CMBR shows an artifact of variance in expansion and we are NOT moving ?

This artifact of observed high temp may well be energy bleeding into our (local) universe bubble from a brane or compression from another universe etc

ie What can be pursued in astrophysics to make the decision assessment more definitive ?

Eg Can we detect variance in an acceleration as well, as what most consider static CMBR ?

PS: In my earlier post I wanted to say "initial BB quantum fluctuations projected throughout inflation" but, ran out of space, hence 'quantum type' so I'm clarifying here as at last min decided to add this post to declare it better to make my point clear - so many get hung up on typos/slips & get angry instead of being polite to just ask...
Whydening Gyre
4 / 5 (4) Apr 28, 2015
Does anyone else see the similarity with the photographs in the article on magnetoelectric domains?

http://cdn.phys.o...sual.jpg
thingumbobesquire
not rated yet Apr 28, 2015
"The galaxy distribution isn't uniform and has no pattern. It has peaks and valleys much like a mountain range. This is what we expect if the large-scale structure originates from quantum fluctuations in the early universe," said Hudson, also associate dean of science, computing.

Yet: " Unexplored areas appear in medium blue."

I think the statement above is, to put it mildly, a little premature.
reset
1 / 5 (2) Apr 28, 2015
Does anyone else see the similarity with the photographs in the article on magnetoelectric domains?

http://cdn.phys.o...sual.jpg


Yes.

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