Have you ever wondered, what if we have a 3D map of entire universe? Then, we easily determine the distribution of matter along the universe and we detect and determine the location of any astronomical objects. DESI is working on this to create the 3 dimensional map of universe. And the detailed map will allow astronomers to investigate important aspects of cosmology, including dark energy and its role in the expansion of the Universe. Its operation period is nearly 5 years.
The new telescope called Dark Energy Spectroscopic Instrument (DESI), the construction of DESI was begun back in 2015. On 2019, it performed the Stage IV dark energy measurement using baryon acoustic oscillations and other techniques that rely on spectroscopic measurements. That we will see in this article.
DESI is a collaboration between several nations: the USA, UK, France, Spain, and Mexico, with the USA’s Department of Energy Office of Science being the principal funder. DESI is the power dark energy spectrograph built on existing 4m Mayall Telescope at the Kitt Peak Observatory in Arizona. At the center, DESI has 5,000 individual, pencil-sized robots. Each of the 5,000 robots controls a single fiber-optic eye, and together they capture a spectra over a wavelength range from 360 nm to 980 nm. with this it can able see from the near ultraviolet, through visible light, and into the infrared portion of the electromagnetic spectrum.
This image shows the spectrum captured by a single one of DESI’s 5,000 fiber-optic eyes. The target is M33, the Triangulum Galaxy. The spectrum reveals the presence of certain elements, and helps measure the distance to the galaxy. Image Credit: DESI Collaboration; Legacy Surveys; NASA/JPL-Caltech/UCLA
On its operation each of the DESI's 5000 pencil sized robots will act as a single unit and observe a selected galaxy at a time. Under best conditions, it’ll complete a set of 5,000 galaxy observations every two minutes, before the entire telescope slews its focal plane to its next set of targets. DESI will repeatedly map the distance to the same 35 million galaxies and 2.4 million quasars, covering about one-third of the sky in its five years of operation. By the end of its observing program, we’ll have a map of the expansion of that part of the Universe over a five year time period. It analyse the lights from distance galaxies and quasars. The light from these galaxies was emitted a long time ago, so in a sense, DESI is looking back in time. Some of its targets are 12 billion years back in time. HOW IT CREATE A 3D MAP OF UNIVERSE ? The principle behind this is baryon acoustic oscillations, which means the fluctuation in density of visible baryonic matter in universe. Those fluctuations can act as a kind of “ruler” in cosmology, similar to how standard candles are used to measure distance. By obtaining spectra of distant galaxies it is possible to determine their distance, via the measurement of their spectroscopic redshift, and thus create a 3-D map of the Universe. This largest 3D map will also contain more information about dark energy. That map will reveal the story of the expansion of the Universe, which is driven by dark energy. During its five-year survey beginning in the second half of 2020, the DESI experiment will observe 35 million galaxies and quasars.
“Galaxies aren’t scattered randomly in space, but instead form a complex pattern from which we can learn about the composition and history of the universe. The unprecedented maps from DESI will allow us to measure how the universe has expanded over time, to see how gravity and dark energy compete to pull and push material apart,” said Professor Daniel Eisenstein of the Center for Astrophysics | Harvard & Smithsonian, who serves as co-Spokesperson of the collaboration.
“The early returns from the instrument were very gratifying after years of development,” said Daniel Eisenstein, a DESI spokesperson and Harvard University astronomy professor. “Now the whole team is eager to learn what DESI data will teach us about the Universe. DESI is about to break the secrete of universe. The universe can't hide its secrete anymore
Post a Comment