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Scientists aim to trace evolution of the universe


An astronomical effort both in the literal and figurative sense, the ALHAMBRA (Advanced Large, Homogeneous Area Medium Band Redshift Astronomical) survey aims to take a deeper look at how the universe has evolved over the last ten thousand million years, with “unprecedented statistical reliability.”
 
Reaching for infinity and beyond
 
More than seventy scientists from sixteen research institutes all over the world comprise the team manning this ambitious project, led by Mariano Moles from the Centre for Studies on the Physics of Cosmos of Aragon (CEFCA). The project was developed in the Astrophysical Institute of Andalusia (IAA-CSIC).
 
"ALHAMBRA represents a decisive step to board pressing issues in cosmology and astrophysics through photometric mapping, that allow getting the accuracy required to the distance of the detected objects," according to Moles.

The researcher adds that "the unbiased character of these mappings allows obtaining relevant data for all cosmic scales,” making the ALHAMBRA project “a precursor of the new long-range mapping that is being proposed.”
 
The ALHAMBRA project utilizes a system of twenty filters covering all optical wavelengths and three infrared filters. Through these filters, stars’ energies are broken by their colors, allowing the system to accurately determine both the distance of half a million galaxies and the energy they emit.
 
The cosmic survey covers an area of four square degrees towards 8 celestial regions, and has so far involved seven years of observation through the 3.5m telescope of the Observatory of Calar Alto in Almeria, Spain.
 
“What gives ALHAMBRA its power, making it an unbeatable survey up to date, is that it implies the detailed study of eight deep sky areas,” states Alberto Molin, a scientist from IAA. “This allows us to be sure that we count on a representative sample and, thus, that any conclusion drawn from this can be extrapolated to the universe as a whole.”
 
The history of the universe, written in the distant stars
 
When astronomers look at distant galaxies, they are not actually seeing them as they are in their current state. As it takes a considerable amount of time for light to travel across such vast distances, what astronomers actually see are snapshots of these galaxies at the point when they emitted the light that reached us today.
 
Thus, by observing the universe’s most distant elements, astronomers are able to get “photographs” of the universe in its infancy – the further away in space the galaxies observed are, the more likely it becomes for astronomers to paint an accurate picture of cosmic evolutionary history.
 
Vicent Martinez, a Professor in Astronomy and Astrophysics at the University of Valencia and a member of the team, affirms that the key to unlocking the secrets of the universe’s evolution is in observing galaxies far, far away. According to Martinez, ALHAMBRA reaches an impressive range of cosmic distance, allowing the researchers to look further into the universe’s history. “[In] astronomy, looking away is to look at the past. We can get to know how galaxies were in early stages of the universe[‘s] history.”
 
Another thing to consider, however, is cosmic variance. Certain regions of the universe are comprised of galaxies with a higher density than others; therefore, concentrating observation efforts to just one or two regions may result in an inaccurate representation of the universe.
 
Molino points out that this makes the ALHAMBRA survey more reliable than other, more “localized” efforts. “To this respect, the ALHAMBRA Survey allowed us to confirm that the COSMOS Project, one of the most widely used for cosmological studies, is not representative of galaxy distribution in the universe, because it is restricted to an area that shows an over-density of galaxies, compared to the average; their closeness makes galaxies to evolve faster and, thus, cosmological studies based on COSMOS have a local character.”
 
Stellar results
 
The images from Calar Alto demonstrate the power of the ALHAMBRA survey’s system. A paper published in June this year also revealed the findings of the survey so far, estimated by the researchers to be about one-fifth of the total data that the project will be able to amass.
 
The usefulness of ALHAMBRA’s findings isn't limited to just enabling humanity to write the universe’s most comprehensive history book, though.
 
"In the last thirteen billion years, gravity has been responsible for the formation of structures, such as galaxies or stars," explains Molino. "Studying how galaxies are arranged allows us to know how the physical properties that controlled the universe at earlier times were.”
 
“It would be like knowing the place and conditions where the seeds were planted in a forest from the trees that we see today."
 
The data gathered from the ALHAMBRA survey is intended to be published as a complete information source upon the project’s conclusion. The researchers believe that its findings will be of tremendous use not just for the international scientific community, but for universities, astronomical associations, and science museums as well.
 
Future research projects such as JPAS (a Spanish-Brazilian endeavor) are expected to take ALHAMBRA’s work a step further, extending its coverage to the entirety of the observable universe. — TJD, GMA News
Tags: astronomy
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