When radio astronomers first detected the regular beat of a pulsar in 1967, there was some initial excitement that it might be a signal from a distant civilization. However, it was soon realized that pulsars were spinning neutron stars, which are the dense remains of supernovae. At the poles of the neutron star’s intense magnetic fields, which don’t have to line up with the rotation axis, particles are accelerated, causing beams of radiation to be emitted. Like a rotating light house beam aimed in our direction, we see a regular pulse of energy from the very dense star.
This is something to keep in mind when hearing about patterns seen in fast radio bursts, which, as the name implies, are short pulses of high frequency radio waves that last for about a millisecond. They were first detected in 2001 and seen infrequently since. A recent study found an unusual pattern in a group of such pulses: Is this ET? Mystery of strange radio bursts from space – New Scientist
We have detected 10 fast bursts of radio waves (FRBs) coming from space in the past 15 year. The delay between the arrival of the first and last waves of each burst is always close to a multiple of 187.5. No known natural process can explain this.
As with radio pulses, a natural phenomenon of some sort, or just noise from some man-made source, will very likely be found to explain these bursts.
- Discrete steps in dispersion measures of Fast Radio Bursts, M. Hippke et al, arxiv.org
- Epic cosmic radio burst finally seen in real time – New Scientist – Jan.19.15
Update Apr.4.15: Another item at NS about the signals: Alien FAQ: 6 questions about strange cosmic radio bursts – New Scientist.