The map has been released by the Dark Energy Consortium and the aim is to produce reference points for scientists to understand where dark matter is, what it is made from and to study the curious phenomenon of dark energy.
The Dark Energy Consortium is a collaboration is made up of research institutions and universities from the U.S., Brazil, the U.K., Germany, Spain, and Switzerland. The consortium is undertaking a detailed optical and near-infrared survey, applying the latest digital technologies from astronomy, to probe the dynamics of the expansion of the universe and the growth of large-scale structures.
The technology includes the 4-meter Victor M. Blanco Telescope located at Cerro Tololo Inter-American Observatory (CTIO) in Chile. This powerful device is outfitted with the Dark Energy Camera (DECam). The telescope was the largest optical telescope in the Southern hemisphere from 1976 until 1998, when the first 8-metre telescope of the ESO Very Large Telescope opened.
The full survey will take five years to complete, with the survey footprint covered ten times within five photometric bands (g, r, i, z, and Y). This is aided by DECam having one of the widest fields of view (2.2-degree diameter) available for optical and infrared imaging. The survey is on its fourth season.
DECam Technology
DECam is a large camera located on the Victor M. Blanco Telescope. The camera has three major components:
Mechanics
The mechanics of the camera are composed of a filter changer with an 8-filter capacity and shutter, plus an optical barrel with 5 corrector lenses, which are attached to a CCD focal plane cooled to −100 °C with liquid nitrogen.
Optics
The camera has u, g, r, i, z, and Y filters , which allow the device to obtain photometric redshift measurements to z≈1, using the 400 nm break for galaxies. These link to a 570-megapixel camera.
CCD
A charge-coupled device (CCD) is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value.
Through the use of the DECam, the Dark Energy Survey studies the dynamics and large scale structure of the universe using four probes. These are Type Ia supernovae (a type of supernova that occurs in binary systems); baryon acoustic oscillations (regular, periodic fluctuations in the density of the visible baryonic – normal – matter; the number of galaxy clusters (the largest known gravitationally bound objects); and weak gravitational lensing (a way to measure the masses of astronomical objects).
As to the map, one of the lead researchers, Professor Ofer Lahav, who works at of University College London told the BBC that the map would provide new insights into how the Universe operates. He says: “Dark energy and dark matter represent probably one of the biggest mysteries in the world of science. And this has generated a lot of interest across the whole of science because it is a major shakeup. And actually we still don’t know what it is”
What might dark matter be?
Dark matter is a hypothetical type of matter which can be distinguished from baryonic matter (that is ordinary matter like protons and neutrons); as well as differentiated from neutrinos and dark energy. Dark matter has never been directly observed. Its probable existence explains a series of puzzling astronomical observations.
The term ‘dark matter’ is used since the phenomenon does not emit or interact with electromagnetic radiation (such as light) rendering it invisible. The presence of dark matter is inferred from its gravitational effects, such as affecting the motions of visible matter. Dark matter is thought to affect the universe’s large-scale structure, especially galaxies. Understanding dark matter could reveal the rate of acceleration of the universe and provide more clues about its formation.
The new map
With the map, the item of space cartography covers about 1/30th of the entire sky. It spans several billion light-years in extent. The red regions have more dark matter than average and the blue regions less dark matter. Overall it supports the theory that around 26 percent of the universe is composed of dark matter.
The map was the result of creating maps of galaxy positions as tracers followed by precisely measuring the shapes of 26 million galaxies to directly map the patterns of dark matter over billions of light-years. Foremost for this was the gravitational lensing technique, which allows scientists to assess the way in which the light is distorted by intervening dark matter, to calculate the distribution of dark matter.
In a research note, another scientist invoked, Dr. said Scott Dodelson of Fermilab, states: “This result is beyond exciting. For the first time, we’re able to see the current structure of the universe with the same clarity that we can see its infancy, and we can follow the threads from one to the other, confirming many predictions along the way.”
Despite the clarity, astronomers are still only scratching the surface of dark matter and what it means in relation to the structure of the universe. The map was unveiled on August 3, 2017 by Daniel Gruen, NASA Einstein fellow at the Kavli Institute for Particle Astrophysics and Cosmology at a special conference convened at the SLAC National Accelerator Laboratory.
Essential Science
This article is part of Digital Journal’s regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week we looked at the controversial scientific developments associated with gene editing. The week before we profiled an interesting development in robotics, where an elongated plant-like robot had bee showcased.
