Green Pea Galaxy May Reveal More about the Big Bang

The questions scientists are trying to answer are fundamental to the universe. It has always remained a matter of discussion as to how this process happened. This, in turn, may confirm the most commonly made hypothesis.

University of Virginia astronomer Trinh Thuan formed an worldwide team of scientists to uncover the mystery behind the re-ionization of universe in its early stages of evolution. Cosmic reionization started out as a flashlight revealing what was out in the darkness.

About a billion years after the Big Bang, the Universe began to heat up for a second time and hydrogen became ionized. If these galaxies were emitting radiation that could heat and strip hydrogen, it’s likely similar galaxies were doing the same thing 13 billion years ago.

A new study in Nature by an global team largely confirmed what astronomers long believed – that this dramatic change was due to galaxies. Trinh’s research colleagues on the paper are at institutions in Ukraine, the Czech Republic, Switzerland, France and Germany. The galaxy was discovered using ultraviolet spectrometer aboard the Hubble Space Telescope and is ejecting a large number of ionized photons into the space. Galaxies were believed to have triggered cosmic reionization, but researchers had yet to find a galaxy emitting enough radiation necessary to reionize hydrogen.

The research findings are vital as it provides a detailed view for investigating the reionization phenomenon.

Dark matter and normal matter, along with neutral hydrogen and helium, made up the early universe. Stars and star clusters are born from clouds of gas, thus forming the first galaxies. Stars emit ultraviolet radiation and ionize photons, heating and stripping the gases apart.

The reason for that re-ionization has been a topic of debate in scientific circles. The dwarf was giving off ionizing photons into the space between galaxies with a power never before observed. Therefore, a team of global researchers turned to the so-called green pea galaxies.

First spotted in 2007 with the Sloane Digital Sky Survey, green pea galaxies are small and appear to glow green, hence their nickname. They appear green to light sensors and are round and compact, like a pea. They are very compact, so could host stellar explosions or winds strong enough to “eject” the ionizing photons. They identified 5,000 and then picked five to study in detail.

Further observations with Hubble should firm up this result, it added.

“We now know, from the scattering of cosmic microwave background photons by reionized electrons and from observations of the absorption by neutral hydrogen in the spectra of extremely distant quasars, that reionization was a gradual process, the midpoint of which occurred approximately 400 million years after the Big Bang”, stated cosmologist Dawn Erb in a statement. Such observations are important in getting a better understanding of the early history of the universe.

It is necessary that the ionizing photos are emitted into the space between the galaxies or else the gas and dust will simply absorb them before they are able to escape.