Epoch of reionisation tagged posts

NASA’s Spitzer Space Telescope has revealed that some of the Universe’s earliest galaxies were brighter than expected. The excess light is a by-product of the galaxies releasing incredibly high amounts of ionising radiation. The finding offers clues to the cause of the Epoch of Reionisation, a major cosmic event that transformed the universe from being mostly opaque to the brilliant starscape seen today.

Researchers report on observations of some of the first galaxies to form in the universe, less than 1 billion years after the big bang (or a little more than 13 billion years ago)...

Cosmic reionisation. Credit: ESA – C. Carreau

ESA’s Planck satellite has revealed that the first stars in the Universe started forming later than previous observations of the Cosmic Microwave Background, CMB indicated. This new analysis also shows these stars were the only sources needed to account for reionising atoms in the cosmos, having completed half of this process when the Universe had reached 700 million years.

With the multitude of stars and galaxies that populate the present Universe, it’s hard to imagine how different our 13.8 billion year cosmos was when it was only a few seconds old. At that early phase, it was a hot, dense primordial soup of particles, mostly electrons, protons, neutrinos, and photons – particles of light...

Hubble Frontier Fields view of MACSJ0416.1–2403 Credit: NASA, ESA and the HST Frontier Fields team (STScI)

Observations have taken advantage of gravitational lensing to reveal the largest sample of the faintest and earliest known galaxies in the Universe. Some of these galaxies formed just 600 million years after the Big Bang and are fainter than any other galaxy yet uncovered by Hubble. The team has determined, for the 1st time that these small galaxies were vital to creating the Universe that we see today.

Hakim Atek’s team has discovered >250 tiny galaxies that existed only 600-900 million years after the Big Bang,one of the largest samples of dwarf galaxies yet to be discovered at these epochs...