It's the Astronomy Online non-Blog, or un-Blog.
Everyone has a blog now and since I am no follower of trends, I decided to merge the blog with the website. And I don't want to neglect the website in favor of posting on the blog.
These are the pages that were on the blog of old:
- Archive (Index of Pages)
- Current Trends
- Soho Live
Google Maps - Mars
Google Maps - Moon
HiRISE - MRO Imaging
Software for the Mac
Starry Night Online
Thank you for visiting!
Chandra and the Sunyaev-Zel'dovich Effect Help Constrain the Age of the Universe:
In a co-authored paper in the Astrophysical Journal, three groups independently constrained the Hubble constant between 73.7 and 77.6. This places the age of the Universe between 12 and 14 billion years.
The distance to 38 galaxy clusters (between a redshift of 0.14 and 0.89) was determined using data from Chandra (X-ray data) as well as data from the Owens Valley Radio Observatory and the Berkeley-Illinois-Maryland Association interferometer arrays. Three different groups of astronomers used the hydrostatic equilibrium (radial variations, temperature, density) of plasma and dark matter distribution and the Sunyaev Zel'dovich Effect, the isothermal Beta-models, and the data excluding the X-ray information to help determine the distances as well as constraint the value for the Hubble Constant. The values are 76.9, 73.7 and 77.6 consecutively.
At this point, it is probably worth expanding on what I just wrote as this is probably Greek to most people.
The Sunyaev-Zel'dovich Effect (SZE) is a wonderful tool that uses photons from the Cosmic Microwave Background (CMB). These photons bounce off (about a 1% chance of) energetic electrons from the hot inter-cluster medium (this bouncing of electrons is called inverse Compton scattering because the electrons are in motion). This scattering causes small distortions in the spectra of the CMB - this is the SZE. Isothermal beta models is a fancy way of evaluating the temperature changes due to distance from a source with constant temperature.
Using this data, computer models and data from the Hubble Space Telescope Key Project, the age of the Universe (using the Hubble Constant) is constrained which is vital in many areas like stellar evolution, globular clusters, galaxy evolution, and the formation of our Universe.
Ref: Bonamente, Massimiliano et al. "Determination of the Cosmic Distance Scale from Sunyaev-Zel'dovich Effect and Chandra X-Ray Measurements of High-Redshift Galaxy Clusters." ApJ, 647:25-54, August 10, 2006.
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