SLIDE 1
- Is SETI a sensible scientific pursuit?
- Are there any signals out there to detect ?
- Why SETI might be really difficult…
- How can we do better in the radio ?
The Search for Extraterrestrial Intelligence (SETI) All-sky Radio - - PowerPoint PPT Presentation
The Search for Extraterrestrial Intelligence (SETI) All-sky Radio - - PowerPoint PPT Presentation
The Search for Extraterrestrial Intelligence (SETI) All-sky Radio SETI Mike Garrett Sir Bernard Lovell Chair, Prof. of Astrophysics. Director Jodrell Bank Centre for Astrophysics Mike Garrett Sir Bernard Lovell Chair, Prof. of Astrophysics.
SLIDE 2
SLIDE 3
- Is SETI a sensible scientific pursuit?
SLIDE 4
PT PR A A PT
PR = PT A2
D2 λ2 e.g. 10 MWatt transmitter located at the nearest star, PR ~ 5x10-19 Watt.
=> Detectable by Lovell Telescope with a SNR ~ 1000 in 1 sec.
Friis transmission formula
SLIDE 5
PT PR A A PT
PR = PT A2
D2 λ2 e.g. 10 MWatt transmitter located at the nearest star, PR ~ 5x10-19 Watt.
=> Detectable by Lovell Telescope with a SNR ~ 1000 in 1 sec.
Friis transmission formula
SLIDE 6
- yes its plausible - our telescopes are sensitive
enough to detect powerful radio transmissions from other (nearby) civilisations in the Milky Way.
- Is SETI a sensible scientific pursuit?
SLIDE 7
Breakthrough Listen
Milner, Worden, Siemion et al. 2016
Parkes GBT
Parkes GBT
SLIDE 8
- Are there signals out there to detect or are we
alone ?
- Is SETI a sensible scientific pursuit?
SLIDE 9
- The evidence suggests success in SETI is
going to be difficult…
- So far no obvious SETI signals have been detected.
- Astronomical data in general show no signatures (so
far) of advanced civilisations.
- Solar system is pristine with no evidence of visitations
from advanced civilisations.
- Intelligent life took a long time to arise on this planet,
and may be universally “rare”.
- Milky Way is big, old and the speed of light is finite.
- From “our experience of one" technical (radio phase)
civilisations may have v. short lifetimes…
SLIDE 10
What can we do to make it easier for ourselves ?
SETI signals may be v. rare…
SLIDE 11
Fast Radio Bursts (FRBs) as an example?
FRBs are bright millisecond flashes of broadband radio emission randomly distributed on the sky…
2ms
- D. Futselaar
SLIDE 12
Fast Radio Burst Properties
Duration: ~ few milliseconds => small size Peak Flux Density: > 0.5 Jy Signal highly dispersed: => extragalactic? Scattered => dense environments? Most events singular? Randomly located across sky No counterparts at other wavelengths Inferred event rates: 1000 x GBR rate.
- D. Futselaar
What are they?
- Coalescing neutron stars/white dwarfs? -
- Evaporating black holes? Planetary debris around NS?
- Plasma turbulence excited by a relativistic jet
- Magnetar flares, SNe, Cosmic strings… ET?
SLIDE 13
FRBs now definitively known to be extragalactic…
z=0.19
Marcote et al. 2017 ChaXerjee et al. 2017, Tendulkar et al. 2017.
SLIDE 14
We still don’t know what FRBs are… and we typically detect almost none of them (or about 1 in 100000! )
Image of Mk2 detection of a burst
Somewhere between 5000-10000 FRBs events per day… !
SLIDE 15
It’s all about Field-of-View (FoV)…
Event Rate ~ FoV . So-3/2+δ
(δ often > 0.5 favouring FoV over sensitivity)
- J.P. Macquart (2013)
If FRB pulses are distributed uniformly through the Universe without significant luminosity evolution, then the rate of FRBs detectable above a where b > 0 is known as the source count index where b > 0 is known as the source count index
SLIDE 16
No coincidence that even the few FRBs we have detected, had to wait for the development of multi-beam receivers…
SLIDE 17
Plans to increasing Lovell Telescope Field of View by x10.
SLIDE 18
Frequency Resolution Frequency Coverage (Bandwidth)
SETI Success!
Temporal Resolution
SLIDE 19
Frequency Resolution Frequency Coverage (Bandwidth)
SETI Success!
Temporal Resolution Sensitivity
SLIDE 20
Spatial Resolution Frequency Resolution Frequency Coverage (Bandwidth)
SETI Success!
Temporal Resolution Sensitivity
SLIDE 21
Spatial Resolution Frequency Resolution Frequency Coverage (Bandwidth)
SETI Success!
Temporal Resolution Sensitivity Field of View
SLIDE 22
Spatial Resolution Frequency Resolution Frequency Coverage (Bandwidth)
SETI Success!
Temporal Resolution Sensitivity Field of View Data Analysis & Signal recognition
?
SLIDE 23
“Argus - multiple-eyed god, who could look in every direction simultaneously. Unlike poor Cyclops, who had only a single line of vision”. First “all-sky” radio telescope concept - Argus - is well-described in “Imperial Earth”
SLIDE 24
“Thousands of elements - little more than stiff wires” -
- Arthur. C.Clarke.
SLIDE 25
“Switching and phasing that would allow Argus to swing its antennas electrically - without moving them physically“ - A.C.C.
SLIDE 26
- 6
SLIDE 27
- 6
SLIDE 28
SKA2-AA
All-sky Radio SETI at cm-wavelengths
SLIDE 29
- 6
MFAA environmental tests MFAA environmental tests
Courtesy: P. Benthem (ASTRON)
SLIDE 30
SETI is difficult… We’ve made enormous progress in many areas of SETI search space, except one - Field-of-View. Radio transient research (e.g. detection of FRBs) may point the way towards SETI success. Investment in Mid-Frequency (cm-wavelength) Aperture Array technology is required… now!
Conclusions
SLIDE 31
Are we just too stupid to see what is under our noses ?
Antoni van Leeuwenhoek
It looks us 2 million years to discover the most prevalent life form on this planet - simple bacteria and the microscopic life, how much longer will it take us to discover life other planets.
SLIDE 32
Thank you!
www.facebook.com/JodrellBankObservatory
@JodrellBankObservatory