Friday, February 21, 2014

Vera Rubin's Work on Galaxies

Vera Rubin spent most of her early career trying to find her place in the male-dominated world of astronomy that was the mid-twentieth century. She faced unintended opposition from early on, starting with a college admissions officer who suggested that she should contemplate becoming a painter of astronomical scenes since she wanted to become an astronomer and liked to paint. Luckily for the astronomical world, Rubin never took this suggestion very seriously.

Rubin finally found her niche in 1965, when she began using a spectrograph to investigate the rotation of galaxies, with W. Kent Ford, and using the Andromeda galaxy as a case study. She had left the mainstream research subject that was quasars and was to make a discovery that she had never expected to make.

When Rubin began investigating the Andromeda galaxy, she was looking at the rotational curves of galaxies. Her work on galaxies showed that there was more to galaxies than could be seen; dark matter. Rubin’s friend Morton Roberts became involved in the project when he overlaid radio observations on a photograph of the Andromeda galaxy, of what appeared to be the end of the galaxy, beyond its visible edge. The rotation velocities, which should have been falling at that point, stayed flat. This meant that there had to be matter there, it was just not visible.

Without the existence of dark matter, Vera Rubin’s findings would not have made sense. She found that galaxies were rotating so fast, that the gravity of the stars contained within would not be significant enough to hold the galaxies together. This is where dark matter comes in – as an explanation as to how these galaxies remain intact. In other words, the theory of dark matter emerged as a result of the galaxy rotation problem. After doing the calculations, Rubin concluded that galaxies have at least an astounding amount of ten times as much dark mass as can be explained by visible stars.

Rubin’s later work with Ford also yielded an effect named after them. A subject of much interpretation and discussion, the Rubin-Ford Effect was found in 1976 and explains the observed bulk motion of a set of galaxies. This was controversial given what was known about the cosmic microwave background, because such high-velocity bulk motions were unexpected. The controversy over the concept eventually ended when more bulk motions were discovered, though some controversy remained over the direction and magnitude of the effect, as well as over potential systematic errors.

It is interesting to note that after Rubin strayed from the mainstream research being done in the field of astronomy, she ended up just as popular as any mainstream astronomer. She was quite decorated, receiving many honors such as the National Medal of Science as well as the Gold Medal of the Royal Astronomical Society, being the first woman to be honored since Caroline Herschel In 1828. Vera Rubin and her work serve as evidence that one should pursue what one is passionate about, the accolades will eventually follow.
Charlotte Townsend