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Cosmologists Make New Maps of Dark Matter Dynamics

Tuesday, July 25, 2017 21:09
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New maps of dark matter dynamics in the Universe have been produced by a team of international cosmologists.

Using advanced computer modelling techniques, the research team has translated the distribution of galaxies into detailed maps of matter streams and velocities for the first time.

The research was carried out by leading cosmologists from the UK, France and Germany.

Dr Florent Leclercq from the University of Portsmouth’s Institute of Cosmology and Gravitation said: “Dark matter is a substance of yet unknown nature that scientists believe makes up more than 80 per cent of the total mass of the Universe. As it does not emit or react to light, its distribution and evolution are not directly observable and have to be inferred.”

Slice through the celestial equator showing the radial component of the velocity field (in kilometres per second). Blue regions are falling towards us and red regions are flying away from us. Galaxies of the Sloan Digital Sky Survey main galaxy sample are overplotted. In the centre of the slice, the infalling dynamics of the Sloan Great Wall, one of the largest structure of the known Universe, can be observed

Credit: University of Portsmouth

The researchers used legacy survey data obtained during 2000 – 2008 from the Sloan Digital Sky Survey (SDSS), a major three-dimensional survey of the Universe. The survey has deep multi-colour images of one fifth of the sky and spectra for more than 900,000 galaxies.

The new dark matter maps cover the Northern Sky up to a distance of 600 megaparsecs, which is the equivalent of looking back about two billion years.

The researchers used a set of phase-space analysis tools and built on research from 2015, which reconstructed the initial conditions of the nearby Universe.


Detection probabilities for different structure types (from left to right: void, sheet, filament, and cluster), in the cosmic web as observed by the Sloan Digital Sky Survey. Structure types are classified using DIVA, an algorithm reflecting the dynamical trend, instead of the current density configuration. The red dot on the map shows our location.

Credit: University of Portsmouth
Dr Leclercq said: “Adopting a phase-space approach discloses a wealth of information, which was previously only analysed in simulations and thought to be inaccessible using observations.

“Accessing this information in galaxy surveys opens up new ways of assessing the validity of theoretical models in light of observations.”

The research is published in the Journal of Cosmology and Astroparticle Physics.


Contacts and sources:
Sophie Hall
University of Portsmouth


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  • Bunker Radio

    Dark matter and dark energy? All energy is measurable and detectable, some forget this. This past year numerous articles came along saying they had proof of dark matter or dark energy, then they found out they were wrong. So there were articles discussing what dark matter and dark energy might be? You see dark energy and dark matter are theoretical, it is something they use to fill in the gaps for things they do not yet know about what keeps this universe cohesive. But the matter may be much more simple and have something to do with this thing called space-time and why the universe expands which may have nothing at all to do with unseen matter or energy, unless you include in the fact of vacuum energy that comes from the expansion of space which is the more likely candidate. I wrote about this on my page on FB and then some days later I actually saw publish an article saying pretty much what I have said in this subject in times past. But this is too much to discuss here and would take near to a life time to explain the back ground of.

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