Article Summary #2

New Method of Determining the Milky Way Bar Patten Speed

I. Minchev, J. Nordhaus, A. C. Quillen, 2010, eprint arXiv:1002.1742, (Mem. S.A.It. Vol. 00, 189)
http://arxiv.org/abs/1002.1742v1

Modeling of the galaxies and the Milky Way specifically, has been an interest for astronomers for many years. Even though in the past the galaxies have been modeled as a perfectly symmetric disk, due to the increase of the amount and quality of data that astronomers can use nowadays, the realistic asymmetries seen in galaxies have become more and more important for constructing accurate galactic models.

The galaxy that would seem the easiest to observe and model is the Milky Way, but difficulties and problems occur in the observations due to the fact that we are located inside the galaxy and an outside observation is currently not possible.

Galaxy modeling is done through numerical simulations, and Minchev et al. 2010 have managed to perform a two-dimensional simulation with a test-particle. The simulation was done initially for a symmetric disk through numerical integration. They simulated measurements of the Oort Constant (C) value in a gravitational potential adding the Galactic bar to their calculations. This value determines the relationship between the gradients of the velocities in the galaxy. The important aspect that resulted from these simulations is that the Oort C value becomes more negative as the velocity dispersion increases.

These results are very useful because they can help improve the previous models. This can be done simply by measuring the Oort Constant values in our galaxy with observational data and then comparing them with the values resulted from the simulations. Also, what influences the value of the Oort Constant is the pattern speed of the galactic bar in the center of the Milky Way.