Well there ya go.
"The observations presented here indicate no evidence for persistent technology-related signals in the microwave frequency range 1 – 10 GHz with threshold sensitivities of 180 – 300 Jy in a 1 Hz channel for signals with 0.01 – 100 Hz bandwidth, and 100 Jy in a 100 kHz channel from 0.1 – 100 MHz. These limits correspond to isotropic radio transmitter powers of 4 – 7x10^15 W and 10^20 W for the narrowband and moderate band observations. These can be compared with Earth’s strongest transmitters, including the Arecibo Observatory’s planetary radar (2 x10^13 W EIRP). Clearly, the energy demands for a detectable signal from KIC 8462852 are far higher than this terrestrial example (largely as a consequence of the distance of this star). On the other hand, these energy requirements could be very substantially reduced if the emissions were beamed in our direction. Additionally, it’s worth noting that any society able to construct a Dyson swarm will have an abundant energy source, as the star furnishes energy at a level of ~10^27 watts."
http://arxiv.org/abs/1511.01606
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Too bad this is no news material.
ReplyDeleteThat's a lot of Watts to be randomly broadcasting in all directions - who would do that? We need detectors several orders of magnitude more sensitive.
ReplyDeleteI'm actually surprised how good the limit is - only 100x more than our own current transmission technology. Not bad considering how long they've been watching for. Of course since sensitivity goes as t^0.5 it will take them 10,000 times longer to reach levels equivalent to current capabilities.
ReplyDeleteBasically all this says is that if their aliens who have built a Dyson sphere around that star, they are making no deliberate attempts to communicate with us using radio waves at the frequencies observed.