科学美国人60秒:Galaxy Might Be Most Distant Seen Object

It was just a tiny galaxy, minding its own business shortly after the big bang. But a chance alignment has brought this ancient galaxy into view. It just might be the most distant object that astronomers have ever seen.

A new study using the Hubble and Spitzer space telescopes has tentatively identified the galaxy, so far away that its light has traveled for 13.3 billion years to reach us.

The galaxy itself is no shining cosmic beacon. In fact it’s only about one one-hundredth the size of the Milky Way. So how did the scopes see it? Chalk it up to a cosmic conjunction.

Some 5.6 billion years ago, its light passed a giant cluster of galaxies. The gravitational pull of the galaxy cluster acted like a lens. As a result, the scopes saw the tiny, distant galaxy in distorted—but greatly magnified—form. The study will appear in The Astrophysical Journal. [Dan Coe et al., CLASH: Three Strongly Lensed Images of a Candidate z ~ 11 Galaxy]

In the cosmologist’s preferred distance measure of redshift, which gauges how much light has been stretched in an expanding universe, the galaxy lies at a redshift of about 10.7. The previous record holder was found at about redshift 10. Literally far out.

—John Matson