- 3200 - DARK ENERGY - latest survey results? Survey results from the DES fit well with the predicted model that is used to map the universe from the beginning of time. In fact, it contradicts previous claims that there was a few percentage difference between the observed universe and the predicted one.
- --------------------------- 3200 - DARK ENERGY - latest survey results?
- DES is the largest cosmological survey ever released. The Dark Energy Survey (DES) took place over 6 years from 2013 to 2019, and looked at over 1/8th of the night sky for a total of 758 nights.
-
- Results released on May 27, 2021, contain analysis of the data from the first half of that observational period, having already released results from the first year back in 2017.
-
- The survey was reviewed by 400 individual scientists from 25 institutions in 7 countries after observations of over 226 million galaxies. Observations were done with the Victor M “Blanco telescope” at Cerro Tololo Inter-American Observatory in Chile.
-
- Measuring 4 meters in width, the Blanco telescope has a resolution of 570 mega pixels, almost 50 times as much as a standard iPhone camera.
-
- The goal of the survey was to “quantify the distribution of ‘dark matter’ and the effect of “dark energy”. These two hardly understood cosmic features make up 95% of all the known “stuff” in the universe.
-
- Despite their 95% prevalence, they are very hard to detect, hence the name “dark”. However, DES provides more insight that ever before into some characteristics of these little understood phenomena. In particular, two cosmological features were central to the survey’s efforts. The first was the “cosmic web”, while the second were “weak gravitational lenses“.
-
- The “cosmic web” is what cosmologists use to describe the structure of galaxies. These massive clusters of gravitationally bound stars aren’t randomly distributed. They form a pattern, with clumps of galaxies banding together to form “galaxy clusters“.
-
- Cosmologists normally attribute those clumped up areas to the presence of higher densities of dark matter and, therefore, gravity. Mapping where they occur in space provides insight into what areas of the galaxy might feature high concentrations of dark matter to study.
-
- Results from universe growth models can then be compared to the cosmic web as a way to check their accuracy in predicting how the universe actually turned out.
-
- Clustering isn’t the only way to detect dark matter though. Gravitational lensing effect happens when light is bent around areas of high gravity, which pockets of dark matter certainly are. Strong gravitational lensing, such as that around blackholes, is a common enough feature of cosmology, producing features such as “Einstein rings“.
-
- “Weak gravitational lensing’ doesn’t have quite as much visual impact but it does provide more insight into that important map of dark matter and dark energy.
-
- “Redshifting” is a feature of astronomical observations where things that are far away and getting further away appear to have the light they emit shifted to the red side of the light spectrum.
-
- A novel calibration technique ws used on 10 different regions of the sky to perform “deep field” searches to see galaxies that were even farther away than their normal observational area. They then used the redshift values calculated in these deep fields to calibrate redshift values in the rest of the surveyed sky.
-
- Even having removed the redshift, more data is always more useful in understanding cosmological phenomena. The DES team also analyzed a number of other phenomena, which included baryonic acoustic oscillations, frequency measurements for massive galaxy clusters, and calculations of some of the features of Type Ia supernovae captured in the survey.
-
- They still have only analyzed half the data, so the other half is expected to add even more detail to the picture of dark energy and dark matter. In addition, new surveys using new instruments, such as the “Vera Rubin Observatory“, are already planned. There’s always more cosmological data to be collected. We still have more to learn.
-
- 3116 - DARK ENERGY - a mystery for science? Dark energy is one of the greatest mysteries in science today. We know very little about it, other than it is invisible, yet it fills the whole universe, and it pushes galaxies away from each other. The result of this force is that it is making our cosmos expand at an accelerated rate.
-
- 3095 - DARK ENERGY - into WIMPs and MACHOs? The more we learn the more we know the less we know. That is certaintly true with astronomy. We have come to the most recent conclusion that 95% of the Universe is “dark”. We call it Dark Energy and Dark Matter. Of course Matter is Energy too, according to energy = mass*c^2 .
-
- 3086 - DARK ENERGY - What is the Universe Made of? Dark Energy was not known until 1998 so we have only 30 years to think about it. The most likely answer is vacuum energy. A vacuum is not really a vacuum but a see of virtual particles and anti-particles going into and out of existence in such a short time they do not defy the laws of physics and cannot be detected using the laws of physics.
- June 25, 2021 DARK ENERGY - latest survey results? 3200
----------------------------------------------------------------------------------------
----- Comments appreciated and Pass it on to whomever is interested. ----
--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email feedback, corrections, request for copies or Index of all reviews
--- to: ------ jamesdetrick@comcast.net ------ “Jim Detrick” -----------
--------------------- --- Friday, June 25, 2021 ---------------------------
No comments:
Post a Comment