MRI: Acquisition of a Stable Hydrogen Maser Frequency Standard for mm/submm VLBI Observations of a Black Hole Event Horizon

点击翻译按钮获取中文摘要

The ability of astronomers to detect fine structure details in distant objects depends upon the angular resolution obtainable from their telescopes and instruments. Angular resolution is related to the wavelength at which the observations are made (the smaller the wavelength, the higher the resolution that can be achieved) and also to the diameter of the observing objective (the larger the objective, the higher the resolution). In most cases the observing objective is the size of the telescope's primary mirror. But when multiple telescopes are used simultaneously and their beams are combined the objective size becomes the baseline distance between the telescopes used. For several decades, radio astronomers have taken advantage of large baselines by coordinating observations between radio telescopes on different continents in a technique termed Very Long Baseline Interferometry (VLBI). This technique has enabled radio astronomers (who work at quite long wavelengths compared to that of visual light) to achieve angular resolutions that rival, and in some cases surpass, the kinds of resolutions available to optical astronomers. Now Dr. Sheperd Doeleman of the MIT Haystack Observatory wants to obtain even higher resolution by moving VLBI observations to shorter wavelengths. His idea will be made possible, in part, through an award from the National Science Foundation's Major Research Instrumentation program that will enable him to obtain a very stable high frequency standard that is necessary to calibrate the observations at the shorter wavelengths. This new standard will enable observations that will lead to a better understanding of the environment surrounding the Black Hole at the center of our Milky Way Galaxy, more than 20,000 light years away.