artist's rendering of ionized hydrogen and oxygen in galaxy SXDF-NB1006-2 detected by the NAOJ Subaru telescope

These photos may hold the answers to the universe's beginnings

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Jul 23, 2016

Oxygen isn’t just a cable TV network—or an element found only on Earth. Or in this galaxy.

Astronomers have found O2 in distant galaxies before, but never lurking in one 13.1 billion light-years away. This means that the Atacama Large Millimeter/submillimeter Array (ALMA) telescope is seeing it as it was when our planet was little more than star stuff and primordial ooze. Galaxy SXDF-NB1006-2 was first detected by the National Astronomy Observatory of Japan (NAOJ) several years ago and still remains the oldest known galaxy ever. Besides being mind-blowingly ancient, the oxygen content in this galaxy 700 million years after the Big Bang can get us closer to understanding which chemical and ionic reactions in space spawned the first stars and planets.

The universe used to be a vast expanse of electrically neutral gas (which basically translates to an infinite chasm of nothingness). Hydrogen and helium floated unconsciously through the darkness without being triggered to react with anything. Then something happened.

Celestial bodies started to shine and emit powerful radiation that ionized the gas. Ionization is a kind of atomic pinball in which atoms gain or lose electrons from interactions with light or collisions with other atoms, subatomic particles or molecules. Ionization via light is hardly surprising given how brightly stars blaze. Hydrogen's causation toward the Epoch of Reionization, as scientists call this period of molecular drama, is still unclear. What the catalyst of this mass reionization was remains a mystery that the composition of pre-Milky Way galaxies could help earthlings understand.

image and close-ups of galaxy SXDF-NB1006-2

“Seeking heavy elements in the early Universe is an essential approach to explore the star formation activity in that period,” said Dr. Akio Inoue of Osaka Sangyo University in Japan, who published the evidence he found in his research on this phenomenon in Science magazine. “Studying heavy elements also gives us a hint [about] how the galaxies were formed and what caused the cosmic reionization.”

SXDF-NB1006-2 is believed to be teeming with hot young stars (not the Hollywood type) by now, though the 13-billion-year-old ALMA snapshot of the teenage galaxy shows an immature star cluster low in oxygen. Evidence of ionized oxygen still means that many immense and luminous stars have been born since then. Stars as massive as our sun incinerate O2 in a nuclear fusion reaction when they heat to astronomically high temperatures—think billions of degrees Kelvin—that aggravate the nuclei of oxygen atoms enough to crash into those of hydrogen and other elements in an explosive release of light and heat.

The negligible amounts of carbon detected by the telescope indicate only traces of un-ionized hydrogen, which means hardly any dust of heavy elements. UV light is able to escape and ionize gases outside the alien galaxy because of its lack of space dust.

“SXDF-NB1006-2 would be a prototype of the light sources responsible for the cosmic reionization,” Dr. Inoue explained. Translation: the images we have of this galaxy are like a Throwback Thursday for the transformation of the cosmos. 

(via Sci News)