antoniseb
22-July-2004, 01:38 PM
Here's a paper about a method of determining the distance to M31 within 1% accuracy using Chandra or XMM-Newton. The method involves carefully watching AGNs that are behind the galaxy in question, and observing the expanding anulus of xrays following a brightness peak in the AGN. The paper claims that Chandra can be used using this method to determine the distance to specific parts of M31 within 1%. M81 can also have its distance determined with somewhat less accuracy. Knowing this distance so precisely will aid in calibrating other intergalactic distance metrics, adding new precision to many cosmological measurements.
Direct Extragalactic Distance Determination Using X-Ray Scattering (http://www.arxiv.org/PS_cache/astro-ph/pdf/0407/0407435.pdf)
Direct Extragalactic Distance Determination Using X-Ray Scattering (http://www.arxiv.org/PS_cache/astro-ph/pdf/0407/0407435.pdf)