Astronomers Hunt for Lithium in Nearby Galaxy

A research by a team of astronomers explores a discrepancy between the amount of lithium believed to be produced during the Big Bang and the amount of lithium in the interstellar gas of the Small Magellanic Cloud.

This image shows the Small Magellanic Cloud, a dwarf galaxy located about 200,000 light years away (ESA / Hubble and Digitized Sky Survey 2)

Dr Christopher Howk of the University of Notre Dame’s Center for Astrophysics, lead author of a paper published in the journal Nature (arXiv.org version), says: “the paper involves measuring the amount of lithium in the interstellar gas of a nearby galaxy, but it may have implications for fundamental physics, in that it could imply the presence of dark matter particles in the early Universe that decay or annihilate one another.”

“This may be a probe of physics in the early Universe that gives us a handle on new physics we don’t have another way to get a handle on right now,” he says.

The team, using observations from ESO’s Very Large Telescope in Chile, measured the amount of lithium in the interstellar gas of the Small Magellanic Cloud, which has far fewer star-produced heavy elements than the Milky Way. In addition to the production of elements by fusion in the core of stars, scientists believe conditions immediately after the Big Bang led to the formation of some elements, including a small amount of lithium.

Stars in the Milky Way have about four times less lithium on the surface than expected by Big Bang predictions. Some scientists suggest that stellar activity might destroy lithium, or the element might sink from the surface through lighter hydrogen, but the remarkably consistent ratio from star to star is a challenge to those explanations.

Observations of gas in the Small Magellanic Cloud revealed the amount of lithium that predictions say would have been produced at the Big Bang, but leave no room for subsequent production of the element.

One explanation could be a novel kind of physics operating at the Big Bang that left less lithium than the Standard Model predicts. To pursue this possibility, the team will conduct three nights of observations on the VLT in November, 2012. They will look for the lithium isotope 7Li in the Large Magellanic Cloud and 6Li in both the Large Magellanic Cloud and the Small Magellanic Cloud. The standard model predicts that no 6Li was created at the Big Bang.

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Bibliographic information: J. Christopher Howk et al. 2012. Observation of interstellar lithium in the low-metallicity Small Magellanic Cloud. Nature 489, 121–123; doi: 10.1038/nature11407