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arXiv · 1910.01148

Choosing a Maximum Drift Rate in a SETI Search: Astrophysical Considerations

Sofia Z. Sheikh·Jason T. Wright·Andrew P. Siemion·J. Emilio Enriquez
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Abstract

A radio transmitter which is accelerating with a non-zero radial component with respect to a receiver will produce a signal that appears to change its frequency over time. This effect, commonly produced in astrophysical situations where orbital and rotational motions are ubiquitous, is called a drift rate. In radio SETI (Search for Extraterrestrial Intelligence) research, it is unknown a priori which frequency a signal is being sent at, or even if there will be any drift rate at all besides motions within the solar system. Therefore a range of potential drift rates need to be individually searched, and a maximum drift rate needs to be chosen. The middle of this range is zero, indicating no acceleration, but the absolute value for the limits remains unconstrained. A balance must be struck between computational time and the possibility of excluding a signal from an ETI. In this work, we examine physical considerations that constrain a maximum drift rate and highlight the importance of this problem in any narrowband SETI search. We determine that a normalized drift rate of 200 nHz (eg. 200 Hz/s at 1 GHz) is a generous, physically motivated guideline for the maximum drift rate that should be applied to future narrowband SETI projects if computational capabilities permit.

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Sofia Z. Sheikh, Jason T. Wright, Andrew P. Siemion, J. Emilio Enriquez. 2019-10-10. Choosing a Maximum Drift Rate in a SETI Search: Astrophysical Considerations. https://doi.org/10.3847/1538-4357%2Fab3fa8

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