MUSE involved in Universe 3D-mapping
A group of astronomers used the tool mounted on the VLT to measure the distance of 189 galaxies, ranging from relatively close to those we see when the universe was less than a billion years. Everything beyond the power of Hubble.
Credit: ESO/MUSE Consortium/R. Bacon
The instrument MUSE mounted on the VLT (Very Large Telescope) ESO has provided astronomers with the best three-dimensional view of the constantly deep Universe. After attaching the region of South Deep Field Hubble (or Hubble Deep Field South in English) for only 27 hours, the new observations reveal the distances, motions and other properties of a number of galaxies far greater than before in this tiny flap sky. Going beyond Hubble and reveal previously invisible objects.
Observing for a long period the same region of the sky, astronomers have been able to create maps of the deep sky that it has revealed a lot of information on the early Universe. The most famous of these is the original Hubble Deep Field, obtained by the Hubble Space Telescope NASA / ESA in the course of a few days towards the end of 1995. This spectacular image, an icon of Hubble, has rapidly transformed our understanding of the content of the universe young. Two years later it was followed by a similar observation in the sky south – the Deep Field South Hubble.
Credit: ESO/MUSE consortium/R. Bacon
These images, however, did not have all the answers – to learn more about the galaxies of the images of deep fields, astronomers had to observe an object at a time with other instruments, a long and difficult task. But now, for the first time, the new instrument MUSE can do both tasks at the same time – and also much faster.
One of the first observations with MUSE after the verification phase on the VLT in 2014 was a long look at the Deep Field South Hubble (or in English Hubble Deep Field South: HDF-S). The results have exceeded expectations.
“After only a few hours of observation at the telescope we gave a quick look at the data and found many galaxies – a very encouraging result. When we came back in Europe we got to explore the data in more detail. It was like fishing in deep waters and every new raid produced enthusiasm and discussions on just fished species, “explained Roland Bacon (Centre de Recherche Astrophysique de Lyon, France, CNRS) Principal Investigator of the instrument MUSE and head of the Audit Committee.
Each point of the look that MUSE has turned to the field HDF-S is not only the pixels of an image but also a spectrum that reveals the intensity of the light into its different constituent colors at that point – about 90 000 spectra in all. Each spectrum covers a range of wavelengths ranging from the blue end of the spectrum to near infrared (475-930 nm). These can detect the distance, composition and internal motions of hundreds of distant galaxies – in addition to capturing a small number of very faint stars in the Milky Way.
Credit: R. Williams (STScI), the HDF-S Team, and NASA/ESA
Although the total exposure time was much lower than that of the Hubble images, data MUSE of HDF-S revealed in this small patch of sky over twenty very faint objects that Hubble had not seen at all. MUSE is particularly sensitive to objects that emit most of the energy to some particular wavelengths, which appear as bright points in the data. The galaxies in the early Universe have usually spectra of this type because they contain hydrogen gas that glows because of ultraviolet radiation of the hot young stars.
“The biggest thrill was when we found very distant galaxies that were not even visible in the deeper images of Hubble. After so many years of hard work on the instrument, for me it was a meaningful experience to see our dreams come true, “said Bacon. Look carefully at all spectrums of the observations MUSE HDF-S, the group of astronomers has measured the distance of 189 galaxies, ranging from relatively close to those we see when the universe was less than a billion years. This is more than ten times the number of distance measures that existed for this area of the sky.
To the nearest galaxies, MUSE can do even more and to study the different properties of the different areas of the same galaxy. This may reveal the rotation of the galaxy and how the properties vary from point to point in the galaxy. It is a very powerful method for understanding how galaxies evolve over cosmic time.