Tuesday, July 28, 2015

A Close Look at the young cosmos

Astronomers for the first time a more detailed look at the development time of normal galaxies succeeded. Observations of an international team of researchers with the radio telescope ALMA plant in the Chilean Atacama Desert show fresh cool gas from which new stars can form, apart from the central region of a young galaxy

Thus ALMA opens a window into the epoch of deionization; the researchers point out in the journal "Monthly Notices of the Royal Astronomical Society".

"For the first time we see early galaxies not only as tiny spots of light, but as objects with an internal structure," says Andrea Ferrara of the Scuola Normale Superiore in Pisa, Italy. Previous observations have rather exceptionally bright - focused objects with high star formation rates - and therefore more visible. But such galaxies are not typical of the young cosmos. The majority of normal galaxies suggested so far, however, only as a nondescript, light weak spot on.

ALMA, the "Atacama Large Millimeter / submillimeter Array", consists of a total of 66 antennas with seven to twelve meters in diameter. The area covered by the large telescope wavelength range is particularly well suited for observing young galaxies in the early universe. The radiation of the first stars in the cosmos has ionized the distributed hydrogen gas in the period between 150 million and one billion years after the Big Bang and thus made transparent for radiation. The exact sequence of this era is not yet, however, little is known.

Ferrara and his colleagues have now succeeded with ALMA to detect the specific radiation of cool gas clouds in the galaxy BDF2399. Astronomers believe that first arise in the central region of a galaxy stars - and then blowing the radiation of these stars cool gas from the environment out. Only further out can remain clouds consist of cooler gas and there produce more star. The position of the observed from the Team radiation away from the galaxy center confirmed this notion.

Combining ALMA observations with computer simulations allows researchers now is to understand key processes in the formation of the first galaxies in detail. The effects of radiation from stars, the survival of molecular clouds, the escape of ionizing radiation and the complex structure of the interstellar medium can be calculated and compared with the first observations. "We have been trying for years to understand the reionization. Now we can finally get our predictions and hypotheses with real data compare, "said Ferrara. "Such observations will help to solve many of the intractable problems that we have with the formation of the first stars and galaxies in the universe."

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