Transcript OSETI with MAGIC Alexandre Armada Tella

OSETI with MAGIC
•Introduction
•Radio SETI
•Optical SETI
•OSETI with MAGIC
•Summary
July 2004
Introduction
Philosophically: since the time of ancient Greek civilization, some
people think that Earth is not a special place:
“Principle of Mediocrity”.
Scientifically:
~ 110 Jupiter-like
planets Search:
discovered so
•recent development on Astrometry and Planetary
far.
rocky habitable planets expected to be found (NEWTON/TPF).
Earth-like planets still
•different environments can also evolve liferemains
taking profit
of some
undetected
due
different energy sources → planets evolving
life mass
muchsensitivity
more
to the
probable.
limit of the
experiments.
After that, to become an intelligent kind of
extra-terrestrial life could be just a question of
time.
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Drake equation
Introduction
The number N of intelligent communicative civilizations in our galaxy
can be estimated by the known as Drake equation
N = R · fp · n · fe · fi · fc · L
where
•R is the yearly rate at which stars form in the galaxy (1 yr-1)
•fp is the fraction of stars that possesses planets (0.5)
•n is the number of planets with environment suitable for life (2)
•fl is the fraction of planets on which life actually develops (1)
•fi is the fraction of these planets in which life develops intelligence (1)
•fc is the fraction of intelligent life forms that developes a culture capable of interstellar
communication (0.1)
•L is the time that this culture will devote to communication (106 yr)
Supposing optimistic parameters → high N (e.g., those in brackets lead
us to N = 105 communicative ETC) → Fermi Paradox: “where are they?”
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Radio SETI (traditional)
Cocconi & Morrison (1959) →Natural
proposition
of MASERS operating at
diffuse background
HI frequency (1.4GHz). Moderate RF/MW background & high
development of radio communication
Frank D. Drake (Project Ozma, 1961) → first
SETI
scientific search based on the idea of C&M,
searching for HI emissions
SETI programs now are restricted by
radio-telescopes observations.
Present searches: try to enhance their
signal detection → interference &
instrumental background reduction.
At the moment, there are no significant
signal for any of the observed targets.
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Optical SETI (OSETI)
Based in optical LASER:
•LASER devices have more power than MASER.
•They operate in the optical range → higher bandwidth (faster
transmission of information) & atmosphere transparency.
•Pulsed emission ~ ns → less natural background (Cherenkov flashes).
→ higher probability for success with more significant results.
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OSETI with MAGIC
MAGIC is the largest
optical reflector ever
built.
•234 m2 mirror surface → high
concentration of light.
•time resolution about 1 ns →
expected pulses (O(1ns)) could be
resolved.
•PMT’s able to detect pulses with
few photons → weak luminosity
excess could be detected from a
star.
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OSETI with MAGIC
Minimum pulse energy to get a Single Pixel Trigger
γ
1ns
PMT
analogical pulse
Single pixel threshold
(discriminator level)
Pulse rate
Logical pulse
•Single Pixel Threshold ~ 8 phe
•Average QE ~ 20 %
•Transmissions ~ 80 %
•Mean λ for optical γ ~ 500 nm
OSETI with MAGIC
COUNTER




  Energy/area|pulse ~ 8.1·10-20 J/m2


Telescope parameter (minimum value)


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OSETI with MAGIC
But LASER traveling :
Adiverged beam
LASER
dt
D

Adiverged beam  4· ·D ·
 dt
2
for reasonable parameters:
•dt ~ 1m
•D ~ 10 pc
OSETI with MAGIC








2
Minimum
Energy Emitted
per Pulse
~ 24 kJ
14th ISCRA Course, Erice 2004
Helios ~ 3.6 MJ
per 3 ns pulse !!!
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OSETI with MAGIC
What can MAGIC do just now?
νLASER ≤ Rspt max to be detected, and also it must be above the
Rspt accidental due to stars luminosity in a significant way.
Rspt accidental can be estimated: for an F type star (like our Sun) with a
magnitude 5.5,

ҒEarth ≈ 2.52·10-8·10-0.4·m J·s-1·m-2
Nphe/ns NSB ~ 0.13 phe/ns
Nphe/ns detected ~ 13.5 phe/ns
↓
P>8phe/ns ~ 1.5·102
Δt ~ 1ns →
↓
Rspt accidental ~ 15 MHz
Rspt Cherenkov ~ 180 Hz
Rspt max readable by MAGIC (expected) ~ 100 MHz
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OSETI with MAGIC
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Following
Kardashev’s
civilization
criteria (based
on the energy
resources
employed):
20
20
•KI (employing300nm
their planet)
500nm
•KII (employing
their star)
700nm
18
18
log10 P(W)
•KIII (employing their whole galaxy)
16
16
Pused (W)
Rdetec (pc)
1011
2
1026
MAGIC
6 parameters
←Helios
(at 14
100
MHz)
14
KI
12
KII
KI→
10
12
63·10
D =1m
t
0
1 1037
KIII↑ closest star
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20·1012 3
log10 D(pc)
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Galactic ↑ Center
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Summary
The MAGIC Telescope is working
now, and Rspt data is taken.
After that, to find an
intelligent kind of
extra-terrestrial life
could be just a question
of time (spent in
analysis)!
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OSETI with MAGIC
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