Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
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. OSETI with MAGIC 14th ISCRA Course, Erice 2004 2 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?” OSETI with MAGIC 14th ISCRA Course, Erice 2004 3 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. OSETI with MAGIC 14th ISCRA Course, Erice 2004 4 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. OSETI with MAGIC 14th ISCRA Course, Erice 2004 5 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. OSETI with MAGIC 14th ISCRA Course, Erice 2004 6 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) 14th ISCRA Course, Erice 2004 7 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 !!! 8 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 OSETI with MAGIC 14th ISCRA Course, Erice 2004 9 OSETI with MAGIC 0 1 2 3 4 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 OSETI with MAGIC 2 20·1012 3 log10 D(pc) 14th ISCRA Course, Erice 2004 4 10 Galactic ↑ Center 10 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)! OSETI with MAGIC 14th ISCRA Course, Erice 2004 11 OSETI with MAGIC 14th ISCRA Course, Erice 2004 12