Cosmology

IAAAInha Amateur Astronomical Association

Cosmology

인하대학교 별지기 4기연세대학교 천문우주학과

김명진

전국 대학생 아마추어 천문회 서울지부 세미나 2006. 12. 2


Contents

• Historical Background• CMB?! • 2006 Novel Prize• A map of the Universe

2006. 12. 2전국 대학생 아마추어 천문회 서울지부 세미나


Historical Background



현대우주론의 태동• 아인슈타인의 상대성 이론

+ 허블의 우주의 팽창 관측 = 현대 우주론의 탄생

• 빅뱅 ( 대폭발 ) 우주론 + 급팽창 이론 + 양자역학적 우주 기원론 = 현대 우주론 2006. 12. 2전국 대학생 아마추어 천문회 서울지부 세미나




Edwin Hubble

• 윌슨산 100 인치 망원경 사용 • 안드로메다 은하까지의 거리 결정 -

-> 섬우주• 우주의 팽창을 관측적으로 증명

( 외부은하의 적색이동 이용 )• 허블의 은하분류법



안드로메다 은하까지의 거리





2006 Novel Prize



Before the Discovery



The Discovery




“for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation”



Why send telescopes into space?



Where does CMB come from?





CMB Anisotropy from COBE


CMB Power Spectrum


Fourier Transform(Quick Introduction)


전국 대학생 아마추어 천문회 서울지부 세미나


Fourier Transform(Quick Introduction)

2006. 12. 2


Statistical Description of Anisotropies



• In late 1960s, P. J. E. Peebles realized that the early universe would have contained sound waves

• When radiation was still trapped by matter, the tightly coupled system of photons, electrons and protons behaved as a single gas

• Then a small disturbance in gas density would have propagated as a sound wave




• Because inflation produced the density disturbances all at once in essentially the first moment of creation, the phase of all the sound waves were synchronized

• The sound waves in the early universe was oscillating in time instead of space

• In this analogy the length of the pipe represent the finite duration when sound waves traveled through the primordial plasma

• Overtones add richness to the sound i.e. cause small scale fluctuations



CMB Power Spectrum

• The greatest variations at about one degree (l = 220)

• This peak is evidence of the fundamental wave

• The subsequent peaks represent the temperature variations caused by the overtones



Analogous to Sound Waves



CMB Power Spectrum• The greatest variations at about one degree (l = 220)

• This peak is evidence of the fundamental wave

• The subsequent peaks represent the temperature variations caused by the overtones

• The series of peaks strongly supports the theory that inflation triggered all the sound waves at the same time

• Sharp drop-off after third peak sound waves with short wavelengths dissipate



2006 년 2 학기 별지기 세미나

• Baryons and Dark matter in the early universe

• Both of them supply mass to the primordial gas and enhance the gravitational pull, but only ordinary matter undergoes the sonic compressions and rarefactions

• At first overtone, gravity is attempting to compress the plasma while gas pressure is trying to expand it.

• This effect explains why the second peak is lower than the first

• By measuring the ratios of the heights of the first three peaks, the density of cold dark matter has been determined

2006. 12. 2


Cosmic Microwave Background Radiation

• CMB is the remnant heat left over from the Big Bang• Evidence for that early universe was smaller, denser

and hotter than present• Now it is observed as 2.7°K microwave radiation• The temperature is almost uniform over the full sky

and it is a sign that it comes from a simpler past• But it has fluctuations in the 10-5 level which is called

‘CMB anisotropy’• CMB anisotropy holds the key to understanding the

origin of structure in the universe : how the primordial plasma evolved into galaxies, stars and planets



A map of the Universe



Millennium Simulation



Millennium Simulation

A 3-dimensional visualization of the Millennium Simulation. The movie shows a journey through the simulated universe. On the way, we visit a rich cluster of galaxies and fly around it. During the two minutes of the movie, we travel a distance for which light would need more than 2.4 billion years.



A map of the Universe


Thank youfor listening!!!

Any questions are invited also E-mail ^^

([email protected])

1999. 4.24 경주 첨성대 – photo by 井



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Cosmology