The Lynx Arc was discovered in 2003 and is considered to be the hottest known star-birthing region in the Universe as of October 2003.

[2] The Lynx Arc was found in a systematic search around galaxy cluster RX J0848+4456 (z=0.570),[1] with the help of a gravitational lens, a 4.5 billion light years distant galaxy cluster (CL J0848.8+4455 lying at z=0.543[2]).

Amongst others the Keck Observatory, the Hubble Space Telescope and ROSAT participated in the search.

Only visible through gravitational lensing by a closer cluster of galaxies, the Arc is a feature of the early days of the universe, when "furious firestorms of star birth" were more common.

It may be going through a short-lived luminous phase that may have lasted for as little as a few million years (Fosbury et al., 2003, in pdf).