Gas Makes a Trip Outside its Galaxy

We are bounded in a nutshell of Infinite space: Blog Post #19, Free Form #3: Gas Makes a Trip Outside its Galaxy

      In the paper “Launching Cosmic Ray-Driven Outflows from the Magnetized Interstellar Medium” by Philipp Girichidis et. al., they discuss more factors that drive galactic evolution and how these correct the present theoretical models to be more comparable to the observed data. In particular, the authors dealt with the formation of galaxies and the role galactic winds, cosmic rays, and thermal release shape the gas around and inside the galaxy. Defining some of the basic phenomenon we will see in this description, a main element of galactic formation is galactic wind, this immense force is present in galaxies from their formation and movement throughout the intergalactic medium, where gravity and more mass from accumulated gas cause these winds which give shape to the galaxy. 

These winds also make gas be ejected out of the galaxy, creating a gas halo around the galaxy. However, galactic winds are not powerful enough to account for all the gas that is seen outside the galaxies, rather another force was recognized to add a significant amount of force, the thermal missions from supernovae. As we know, supernovae are a type of star that grows to an incredible size and explode in the most amazing of ways, creating nebulae, incredible light emissions which outshine entire galaxies, and in some cases black holes.

Aside from the explosions themselves, these stars put out great energies in the form of thermal radiation, which also pushes the gas into a halo…but it still doesn’t fit the observed data. So, there must be another force that pushes the gas outside the center of the galaxy. This scientific group, located in part at the Max Planck Institute in Germany, found that cosmic rays, “high energy protons, electrons, and nuclei moving near the speed of light”, contribute significantly to the gas ejection. After these sources were all properly identified and their contribution to the gas movement weighed, the new theoretical projection matches up with the observed gas ejection.  

Black= Ejections from Thermal Energy;  Blue = Ejections from Cosmic Rays; Red= Combined Theo. Model; Yellow= Observed Data

All these measurements and continuations of experiments serve to illustrate how more and more experimental and theoretical scientists continue to work together within their fields to develop the best description and understanding of astronomical phenomenon. They find new and innovative ways to describe the way galaxies are shaped and the way they evolve, creating richer and more fundamental analyses of the process of interstellar formation. 

Reference:

http://astrobites.org/2015/10/01/cosmic-rays-make-for-windy-galaxies/