Physics 133: Extragalactic Astronomy and Cosmology Lecture 10; February 12 2014.
Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.
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Transcript of Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.
![Page 1: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/1.jpg)
Cosmology and extragalactic astronomy
Mat Page
Mullard Space Science Lab, UCL
Revision Lecture
![Page 2: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/2.jpg)
Recap of everything!• Galaxies:
– Classification+Structure– Dark Matter
• Hubble’s law– redshift and distance indicators
• Cosmological Principles, Olbers’s Paradox
• Cosmic microwave background– results and implications
• Inflation
• Nucleosynthesis, baryogenesis
![Page 3: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/3.jpg)
Galaxies and dark matter
• Hubble’s tuning fork diagram
• Spirals + barred spirals– Sa: large bulge, tight arms. – Sc: small bulge, loose arms
• Star formation, gas and dust in arms
• Density wave model
• Rotation, rotation curve -> dark matter
• MACHOs, WIMPs, how they are detected
• 109-1011 Mo
![Page 4: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/4.jpg)
Galaxies and dark matter
• Ellipticals
• E0-E7, En where n=10(1-b/a)
• Classified according to view from Earth
• Old, red stars (no star formation)
• little gas, little dust
• 105-1013 Mo
![Page 5: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/5.jpg)
• Lenticulars (S0)– like spirals but no arms, just disc
• Irregulars– tend to be small, no definite structure
![Page 6: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/6.jpg)
Where are the galaxies and how did they form?
– Galaxies form in dark matter haloes– Most of the galaxies in rich clusters are
ellipticals– bottom up vs. top down– hierarchical model - ellipticals built up by
merging of disc galaxies– spirals created when galaxies accrete gas (with
angular momentum) from the intergalactic medium
![Page 7: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/7.jpg)
• Massive accreting black holes in galactic nuclei.
• 90% are radio quiet, but can be identified by their strong emission lines.
• Most quasars are seen at large redshifts (z>0.3)
Quasars
![Page 8: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/8.jpg)
Hubble’s law
![Page 9: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/9.jpg)
Hubble’s law
![Page 10: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/10.jpg)
Cosmic distance ladder
![Page 11: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/11.jpg)
Cosmic microwave background:
![Page 12: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/12.jpg)
Inflation
• What is it?– A period of rapid expansion in the early
Universe– Caused by a state change as the Universe cools
• Why do we need it?– The horizon problem– large scale structure– flatness– the monopole problem
![Page 13: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/13.jpg)
Olbers’s paradox
• Night sky should be infinitely bright!• Solution:
– The Universe is only 14 billion years old!– Light from stars more distant than 14 billion light
years has not have reached us yet.– There is a limit to the size of the Universe which can
illuminate the night sky.– The sky is allowed to be dark.
![Page 14: Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Revision Lecture.](https://reader035.fdocuments.us/reader035/viewer/2022062417/5515dc2b550346dd6f8b4ae7/html5/thumbnails/14.jpg)
Finally:
• Good luck to you all!