What’s the best way to explain how galaxies grow? Spiders, says astrophysicist Jorge Sanchez Almeida.
Almeida and his team recently set out to confirm existing the existing astrophysics theory that dwarf galaxies grow by moving, spider-like, across the “cosmic web”. This cosmic web is made up of blobs of gas and is underpinned by a skeleton of dark matter. The blobs of cosmic gas have especially low levels of oxygen, and oxygen is easier to measure and detect than other cosmic gases—so we can use its level as an indicator. It is thought that as the blobs of gas are pulled into orbit of hungry spider galaxies, they are eaten and used as fuel, triggering a new burst of star formation. This causes the hungry galaxies to grow.
The spider theory has been hard to prove. Blobs of gas don’t emit much light, so scientists have hard a tough time searching for them. However, Almeida and his team were able to find what has been described as a spider galaxy “a smoking gun” by focusing on a number of smaller, fainter galaxies. These galaxies have naturally lower rates of star formation if they don’t get influxes of new gas.
By looking at the correlation between oxygen levels and bright, star-forming regions of these galaxies, Almeida and his team found that the star-forming regions had lower levels of oxygen than the other regions. This suggests that new stars are forming in the regions where the spider galaxies were eating the gas blobs.
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Astrophysicists want more evidence to confirm the process, but say that it might help us explain more about dwarf galaxy growth and the cosmic web.