Introducing "Himiko," the Primordial Blob

Last week my interest was piqued by a news release from the Carnegie Institution of Washington about an enormous blob of matter discovered by CIW fellow Masami Ouchi and an international team of collaborators.

The object spans some 55,000 light-years, roughly the size of a galaxy. This alone wouldn't make it noteworthy, since astronomers know of other large masses in the early universe. What does, however, is its age. Based on the extreme redshifting of its hydrogen spectrum, from a rest wavelength of 121.6 nanometers in the ultraviolet to 923 nm in the infrared, Ouchi estimates that this primordial blob is 12.9 billion light-years away.

In other words, this object, located in the constellation Cetus, came together when the universe was about 800 million years old. (Astronomers can't really see farther back in time, because for a half billion years beforehand space was filled with opaque gas. Only when the first galaxies and quasars "turned on," ionizing much of the gas, did the universe become transparent to light.)

It's an important discovery, because astronomers hadn't believed such a large structure (with an estimated mass of 40 billion Suns) could have assembled so soon after the Big Bang.

But what is it, exactly? As the team notes in May 10th's Astrophysical Journal, it could be a massive gas cloud energized by a supermassive black hole, a primordial galaxy gobbling up gas from its surroundings, two young galaxies colliding, or a single massive galaxy.

Whatever its origin, the big blob now has a name: Himiko. Ouchi and his team discovered it with Japan's Subaru telescope atop Mauna Kea in Hawaii, so they named it after a mysterious, ancient queen in Japanese folklore.