DOC PREVIEW
MSU AST 115 - Introduction to Cosmology
Type Lecture Note
Pages 2

This preview shows page 1 out of 2 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 2 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 2 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

AST 115 1st Edition Lecture 34 Outline of Last Lecture I. Quasars continuedII. Active GalaxiesIII. Types of Active Galaxiesa. Seyfert Galaxiesb. Double – Lobbed (radio) Galaxyc. Jet GalaxiesIV. The Power Source of Quasars and AGNV. Gravitational LensesOutline of Current Lecture I. Intro to CosmologyII. Observational Cosmologya. Olbers’ Paradoxb. Expanding Universei. The important implications of an expanding universec. Quasar Censusd. Cosmic (Microwave) Background Radiation (CMB)Current LectureIntroduction to Chapter 14: Cosmology Cosmologyo Cosmology: study of the origin, structure, and evolution of the universe (U). Universe: everything that there is.- Including stars, comets, planets, gas, dust, galaxies, etc. and…SPACE Observational Cosmologyo Olbers’ Paradox If the universe is infinite with stars uniformly distributed within it, and is static, then “why is the night sky dark?”(Two of the resolutions of the Paradox are possible)o The Expanding Universe One profound implication of Hubble’s result is that the universe is observed to be expanding.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. In an expanding universe, the velocity at which a galaxy recedes from us increases with increasing distance. Are the more distant galaxies flying through space at ever greater speeds?- No. Space itself is expanding, carrying clusters and superclusters of galaxies with it. The galaxies themselves dot not get larger. All observers in the universe see the same result. All other galaxies seem to recede from any given galaxy. Thus, there is NOT a center to the universe (it is a meaningless concept). We must also realize that it is not strictly correct to use the Doppler Effectto describe the redshifts seen in the spectra of galaxies. This should be called the “Cosmological Redshift”. For small redshifts, the Doppler Effect is reasonably accurate. The important implications of an expanding universe:1. There is no center2. There is no edge3. The expansion rate is slowed by gravity4. The expansion rate is increased by “dark energy”5. #4 is greater than #3, so the expansion of the universe is accelerating (Supernova Type Ia results: farther than expected; expansion rate has increased over at least 6 billion years).6. The universe began in a hot, dense state known as the “Big Bang”. This marked the beginning for time and space.o Quasar Census The number of quasars per unit volume increases out to about z(redshift) = 2 then drops off and is close to zero for z ˃ 4.  This means that the universe is changing as the Big Bang Theory predicts. There are no quasars locally now, but lots far away, long ago.o Cosmic (microwave) Background Radiation = “CMB” Discovered in 1965 by Penzias and Wilson using a (microwave) radio telescope. This radiation comes to us from all directions in space equally and all the time. The CMB is very strong evidence of the Big Bang event; Point a radio telescope in a random direction. Look out into space as far as possible. The earliest back in time that we can see is when the universe cooled to about 3,000˚K at age 380,000 years and became transparent to photons for the first time. The peak emission from that spot in the universe was at that time in the visible. But the Hubble Law says that if radiation comes from great distance, it will be redshifted to infrared and radio (microwave)


View Full Document

MSU AST 115 - Introduction to Cosmology

Type: Lecture Note
Pages: 2
Documents in this Course
Load more
Download Introduction to Cosmology
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Introduction to Cosmology and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Introduction to Cosmology 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?