Tag: reionization

Out Of The Darkness

Simulation of the "Dark Ages," a period between 380,000 years and 4 million years after the Big Bang. The universe was made up primarily of hydrogen in a neutral state, which did not easily connect with any other particles. NASA/WMAP

Simulation of the “Dark Ages” of the universe, a period predicted by theorists to have lasted as long as several hundred million years after the Big Bang.  The first hydrogen atoms in the universe had not yet coalesced into stars and galaxies. (NASA/WMAP)

Before there were planets in our solar system, there was a star that would become our sun.  Before there was a sun, there were older stars and exoplanets throughout the galaxies.

Before there were galaxies with stars and exoplanets, there were galaxies with stars and no planets.  Before there were galaxies without planets, there were massive singular stars.

And before that, there was darkness for more than 100 million years after the Big Bang — a cosmos without much, or at times any, light.

So how did the lights get turned on, setting the stage for all that followed?  Scientists have many theories but so far only limited data.

In the coming years, that is likely to change substantially.

First, the James Webb Space Telescope, scheduled to launch in 2018, will be able to look back at distant galaxies and stars that existed in small or limited numbers during the so called Dark Ages.  They gradually became more prevalent and then suddenly (in astronomical terms) became common.  Called the epoch of cosmic “reionization,” this period is an essential turning point in the evolution of the cosmos.

Less well known but also about to begin pioneering work into how and when the lights came on will be an international consortium led by a team at the University of California, Berkeley. Unlike the space-based JWST,  this effort will use an array of radio telescopes under construction in the South African desert.  The currently small array will expand quickly now thanks in large part to a $9.6 million grant recently announced from the National Science Foundation.

Named the Hydrogen Epoch of Reionization Array (HERA), the project will focus especially on the billion-year process that changed the fundamental particle physics of the universe to allow stars, galaxies and their light burst out like spring flowers after a long winter.  But unlike the JWST, which will be able to observe faint and very early individual galaxies and stars, HERA will be exploring the early universe as a near whole.

 

Before stars and galaxies became common, the universe went through a long period of darkness and semi-darkness, but ended with the Epoch of Reionization. (S.G. Dorgovski & Digital Media Center, Caltech.)

Before stars and galaxies became common, the universe went through a long period of darkness and semi-darkness, but ended with the “Epoch of Reionization.” (S.G.

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Faint Worlds On the Far Horizon

Faintest distant galaxy ever detected, formed only 400 million years after the Big Bang. NASA, ESA, and L. Infante (Pontificia Universidad Catolica de Chile)

Faintest distant galaxy ever detected, formed only 400 million years after the Big Bang. NASA, ESA, and L. Infante (Pontificia Universidad Catolica de Chile)

For thinking about the enormity of the canvas of potential suns and exoplanets, I find images like this and what they tell us to be an awkward combination of fascinating and daunting.

This is an image that, using the combined capabilities of NASA’s Hubble and Spitzer space telescopes, shows what is being described as the faintest object, and one of very oldest, ever seen in the early universe.  It is a small, low mass, low luminosity and low size proto-galaxy as it existed some 13.4 billion years ago, about 4oo million years after the big bang.

The team has nicknamed the object Tayna, which means “first-born” in Aymara, a language spoken in the Andes and Altiplano regions of South America.

Though Hubble and Spitzer have detected other galaxies that appear to be slightly further away, and thus older, Tayna represents a smaller, fainter class of newly forming galaxies that until now have largely evaded detection. These very dim bodies may offer new insight into the formation and evolution of the first galaxies — the “lighting of the universe” that occurred after several hundred million years of darkness following the big bang and its subsequent explosion of energy.

This is an illustration by Adolf Schaller from the Hubble Gallery (NASA). It is public domain. It shows colliding protogalaxies less than 1 billion years afer the big bang.

This is an illustration by Adolf Schaller from the Hubble Gallery and shows
colliding protogalaxies less than 1 billion years after the big bang. (NASA)

Detecting and trying to understand these earliest galaxies is somewhat like the drive of paleo-anthropologists to find older and older fossil examples of early man. Each older specimen provides insight into the evolutionary process that created us, just as each discovery of an older, or less developed, early galaxy helps tease out some of the hows and whys of the formation of the universe.

Leopoldo Infante, an astronomer at Pontifical Catholic University of Chile, is the lead author of last week’s Astrophysical Journal article on the faintest early galaxy.  He said there is good reason to conclude there were many more of these earliest proto-galaxies than the larger ones at the time, and that they were key in the “reionization” of the universe — the process through which the universe’s early “dark ages” were gradually ended by the formation of more and more luminous stars and galaxies..

But the process of detecting these very early proto-galaxies is only beginning, he said, and will pick up real speed only when the NASA’s James Webb Space Telescope (scheduled to be launched in 2018) is up and operating. … Read more

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