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Cosmology and Astrophysics Metin Arık 19 March 2009 Sci 102 Lecture.

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... konulu sunumlar: "Cosmology and Astrophysics Metin Arık 19 March 2009 Sci 102 Lecture."— Sunum transkripti:

1 Cosmology and Astrophysics Metin Arık 19 March 2009 Sci 102 Lecture

2 Cosmology: Black Holes, Dark Matter and Dark Energy The three most iportant aspects of modern cosmology are Black holes, Dark Matter and Dark Energy. I will review these concepts which are deeply related to the evolution of the expanding universe. Black holes are formed after giant stars undergo a super-nova explosion. Matter falling into a black hole undergoes the most violent reaction known in the universe. So we regard black holes as visible objects. On the other hand dark matter and dark energy form 97% of the present universe. We cannot see them directly but we can deduce their existence indirectly from observations.

3 ZAMAN milyarxmilyarxmilyarxmilyar saniye : proton ömrü bundan daha uzun milyarxmilyarxmilyar saniye : ? milyarxmilyar saniye : evrenin yaşı milyar saniye : insan ömrü bir saniye : şu an bir saniyenin milyarda biri : zayıf bozunma ömrü bir saniyenin milyarda birinin milyarda biri : elektromanyetik bozunma ömrü bir saniyenin milyarda birinin milyarda birinin milyarda biri : kuvvetli bozunma ömrü bir saniyenin milyarda birinin miyarda birinin milyarda birinin milyarda biri : ? bir saniyenin milyarda birinin milyarda birinin milyarda birinin milyarda birinin milyarda biri : Planck zamanı

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5 BLACK HOLES May 1, 2006 VLBA Reveals Closest Pair of Supermassive Black Holes Astronomers using the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope have found the closest pair of supermassive black holes ever discovered in the Universe -- a duo of monsters that together are more than 150 million times more massive than the Sun and closer together than the Earth and the bright star Vega.Very Long Baseline Array (VLBA) "These two giant black holes are only about 24 light-years apart, and that's more than 100 times closer than any pair found before," said Cristina Rodriguez, of the University of New Mexico (UNM) and Simon Bolivar University in Venezuela. Black holes are concentrations of mass with gravity so strong that not even light can escape them. The black hole pair is in the center of a galaxy called , some 750 million light-years from Earth. Astronomers presume that each of the supermassive black holes was once at the core of a separate galaxy, then the two galaxies collided, leaving the black holes orbiting each other. The black holes orbit each other about once every 150,000 years, the scientists say.

6 Redshift 5.0 Quasar The arrow in this image points out the record-breaking redshift 5.0 quasar discovered by the Sloan Digital Sky Survey. That faint red dot of light represents an object that is actually a hundred times as luminous as a typical galaxy. Sky Survey astronomers identified this object as a possible high-redshift quasar on the basis of its exceptionally red color compared to ordinary stars and galaxies. Followup spectroscopy with the ARC 3.5-meter telescope confirmed that this unassuming speck was indeed the most distant quasar known to date. SDSS Collaboration

7 2000 April 19 Redshift 5.8: A New Farthest Quasar Credit: Stephen Kent (FNAL), SDSS CollaborationStephen KentFNALSDSS Collaboration

8 The red dot in this picture is the most distant quasar ever discovered (at least as of October 2003). The redshift 6.4 quasar is seen at a time when the universe was just 800 million years old. The light-travel time from this object to us is about 13 billion years. Sloan Digital Sky Survey at Apache Point Observatory

9 UZAY milyarxmilyarxmilyar metre: en uzak galaksi milyarxmilyar metre: galaksi içi milyar metre: güneş sistemi içi metre: insan bir metrenin milyarda biri: molekül bir metrenin milyarda birinin milyarda biri: proton bir metrenin milyarda birinin milyarda birinin milyarda biri: elektron ? bir metrenin milyarda birinin milyarda birinin milyarda birinin milyarda biri: Planck uzunluğu

10 VLA image (green) of radio emission from HCN gas, superimposed on Hubble Space Telescope image of the Cloverleaf galaxy 11 billion light years away. The four images of the Cloverleaf are the result of gravitational lensing 10 December 2003 Astronomers Discover Most Distant Galaxy Showing Key Evidence For Furious Star Formation

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12 GRAVITATIONAL LENSING

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14 Chandra X-ray Observatory images a distant quasar The X-ray image of the quasar PKS , a highly luminous source of X-rays and visible light about 10 billion light years from Earth, shows an enormous X-ray jet that extends at least a million light years from the quasar. The jet is likely due to the collision of a beam of high-energy electrons with microwave photons. The high-energy beam is thought to have been produced by explosive activity related to gas swirling around a supermassive black hole. The length of the jet and the observed bright knots of X-ray emission suggest that the explosive activity is long-lived but intermittent. On their way to Earth, the X-rays from the quasar pass through a galaxy located 4 billion light years away. Atoms of various elements in this galaxy absorb some of the X-rays, and produce a dimming of the quasar's X-rays, or an X-ray shadow. In a similar way, when our body is X-rayed, our bones produce an X-ray shadow. By measuring the amount of absorption astronomers were able to estimate that 4 billion years ago, the gas in the absorbing galaxy contained a much lower concentration of oxygen relative to hydrogen gas than does our galaxy - about five times lower. These observations will give astronomers insight into how the oxygen supply of galaxies is built up over the eons.

15 KOZMOLOJİ: evrenin evrimi Gözlem: evren genişliyor. Evren sonluysa ve zamanda geri gidersek bir “nokta” dan başlamış olmalı, buna büyük patlama diyoruz. Büyük patlama yaklaşık 14 milyar yıl önce olmalı. Evren başta çok sıcak olmalı, madde yerine radyasyon dolu olmalı. Einstein denklemleri bize böyle bir evrenin gittikçe yavaşlayan bir hızda genişlediğini gösteriyor. Evren yeteri kadar genişleyip soğuduğunda atomlar (madde) oluşuyor. Fotonlar halinde kalan radyasyon soğuyarak bugüne kadar kalıyor ve günümüzde ölçülebiliyor. Einstein denklemleri madde dolu bir evrenin de gittikçe yavaşlayan bir hızda genişleyeceğini ve evren sonlu ise bir zaman sonra daralmaya başlayacağını söylüyor. Böyle bir evrenin niye bugün gözlemlediğimiz kadar büyük olabildiğini açıklamakta zorlanıyoruz. Başlangıçta evrenin eksponansiyel artan hızla genişlemiş olduğu bir süreç olmalı, bu sürece “enflasyon” diyoruz. Yakındaki galaksileri gözlemleyerek evrenin bugünkü genişleme hızını, uzaktaki galaksilere bakarak evrenin geçmişteki genişleme hızını ölçebiliyoruz. Son ölçümler gösteriyor ki evren şu anda da artan bir hızla genişliyor, ama 5 milyar yıl önce madde dolu bir evren gibi gittikçe yavaşlayan bir hızda genişliyordu.


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