HFLS3, an extremely distant galaxy, is feverishly producing stars at an alarming rate. The galaxy is about 13-billion light-years away, making it less than a billion years old. This is all fine and dandy except, according to our current theories on galaxy evolution, HFLS3 shouldn’t exist.
Even though the ESA’s Herschel Space Observatory has one foot out the door to decommission, it managed to spy this distant star factory. The small, faint, red smudge that first appeared in Hershel’s images look deceiving, hiding the awesome size and power of this galaxy – fortunately, we have calculations for that.
HFLS3 is producing stars about 2,000 times more rapidly than the Milky Way is at present time. Altogether, this is one of the highest rates of star-formation seen an any galaxy anywhere (or at any time) in the universe. The galaxy is estimated to be around the 880-million year mark after the big bang (yes, that’s million with an ‘m’). More surprisingly is the fact that HFLS3 is extremely massive; almost as massive as the Milky way weighing in at 140-billion solar masses (the Milky Way is estimated to be between 580-billion and 1-trillion solar masses). Of course, we are viewing this monster as it appeared some 13-billion years ago. Today, as in right now in the modern universe, this galaxy should have grown and evolved to be the most massive galaxy known in the local universe. According to our current models and theories for galaxy evolution, a galaxy as young and as massive as HFLS3 should simply not exist.
Current cosmological theories state that the first galaxies in the universe were small, having a mass of only a few billion solar masses (or, anywhere from a few million to a few billion stars). As the universe aged, galaxies merged with each other and got larger until we reach the modern epoch. The question naturally arises, ‘when did the first large galaxies form?’ Knowing the answer to that question can really help us to refine our theories regarding the evolution of galaxies and the universe.
Now, the real question is this, does HFLS3 represent a statistical anomaly – a heavyweight that formed quite by mistake, or is it a standard for galaxy formation in the infant universe? Answering that question is like looking for a needle in an enormous haystack, but it won’t stop teams using the Hershel telescope and others like it to probe the early universe for the answers.