Download Things that Go Bump in the Night – Lecture Notes

Things that Go Bump in the Night – Lecture Notes
Do these things exist?
 We don’t see them.
o Electrons
 The evidence is indirect.
 The question is is there other evidence.
Aren’t these things hypothesized to salvage evolutionary ideas?
 There are other examples – antibiotic resistant bacteria - that are not
necessarily evolutionary but can be explained in other terms.
 Separate the physical data from the speculations
Mass - how much matter you have…how much stuff.
Weight is the effects of gravity on mass…actually three factors
 Earth Mass, Distance from center of the earth, the fundamental constant of
the universe
Astronomy uses binary star systems to mass through mutual gravity
 Sun mass to earth 330,000 to one
How do we measure mass?
 By gravitational attraction
 In astronomy, orbital motion
 Binary stars
Black Holes
 What is a black hole?
 Small massive object for which the escape velocity is greater than the speed
of light
o The earth’s escape velocity is 25,000 mph or 7 miles per second
 First hypothesized:
o JOHN MITCHELL(1783)
o Pierre-Simon LaPlace (1795)
 Modern theory of Black Holes (1960s)
o Pulsar discovered in 1960s
o Black Hole coined 1963
o From theory of relativity – no material object (i.e. particle) can move
faster than the speed of light
o Matter has angular momentum constraints therefore cannot fall
directly into a black hole – it spirals picking up speed as it falls in
having a very deep gravitational potential well
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Is moving a signif fraction of a speed of light
Matter is compressing into a smaller volume, speeding up and
interacting as friction
Friction causes heat
Motion 150,000 miles per second
Heat causes X-ray emissions (copious amounts)
Magnetic effects causing ionization of materials
Charged particles accelerate causing material to be jetted out
along the longitudinal planes
Cannot see it but can model it through radio telescope images
 Reveals the accretion disk
 Reveals the jets
Do see this behavior in
 Quasars
 Galaxy centers (nuclei)
 Binary Stars
Types of Black Holes
o Classified by mass
 Micro Black Holes – can evaporate quantum mechanically – not
ever seen
 Stellar Size Black Holes
 3-20 X the mass of the sun
 Intermediate Size Black Holes
 Thousands of solar masses
 Supermassive Black Holes
 Millions of solar masses – at core of galaxies
Binary Star – Black Hole System
BLACK STELLAR HOLES
 Causes an accretion disk and jet, plus hot area adjacent to star
 Heat area emits x-rays
 Stellar Black Holes are Best detected in stellar binary systems
 Call the region a Roche Lobe
 Companion fills Roche lobe
 Matter transfers
 Matter settles into accretion disk
 Accretion disk gets very hot
 Steep gravitational potential well
 Thermalized motion
 VERY HOT X-rays
 X-ray sources have been observed to orbit around another star
X-RAY Binary (XRB)
 Binary star – solve for mass
 Know mass of visible companion
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Difference gives mass of compact object
Two kinds of compact objects:
o Neutron star (mass < 3 solar masses) – discovered in 1967, predicted
since the mid-1930’s
o Black Hole (mass > 3 solar masses)
BLACK HOLE EXAMPLES
 Cygnus X-1 (11 solar masses)
 V616 Mon (11 solar masses)
 Many others
SUPERMASSIVE BLACK HOLES
 LURKING IN THE CENTER OF GALAXIES
 Detected by motions of stars around the black holes
 Mass determined from Kepler’s third law
 More exotic-power AGNs and QSOs
o Active Galactic Nuclei
o Quasi-stellar objects (1963) QUASARS
EXAMPLES
 Milky Way’s SGR A*
o S2 orbits in eccentric 15.2 year period orbit
o Closest Approach is 17 light hours
o 2.6 million solar masses
 M104 Black Hole
o Star near center orbit requiring a billion solar mass object
WHERE IS THE EVOLUTION?
 No clear explanation for micro black holes
 Stellar black holes come from implosions of cores of very massive stars
(supernovae) – never witnessed
 No origin for intermediate size black holes
o Mergers?
 No origin scenario for supermassive black holes
o Mergers?
o Primordial process – form in early universe, but not happening today
by some unknown process – that is not science.
DARK MATTER
 First suggested by Fritz Zwicky in 1933
 Coma Cluster (of galaxies)
o Dynamic Mass from motion of galaxies, assuming bound orbits
o Lighted mass – so much star matter produces so much light
o Dynamic mass greatly exceeded light mass
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 By a factor of 8 or 10 to one for every cluster that he looked at
 Range of 2 X to 20 X
1970’s Vera Rubin – studied the Andromeda Galaxy and measured the speed
using the Doppler effect
studied faint objects beyond the light drop off of the galaxy 99 % gone
Compared speed to Keplarian curve of Velocity versus Distance
o Told her that there was a lot more mass beyond where the light drops
off – more mass than in lighted area
o Therefore by 1980s Dark matter was being taken seriously by
astronomers
Gravitational lensing of distant objects by nearby clusters of galaxies
WHAT IS DARK MATTER
 We do not know.
 Many theories - All theories to date have been shot down.
 Probably some form of matter that we don’t know of yet
o If so we can’t explain about 90% of the matter of the universe.
EVOLUTION?
 None really
 Except, if you believe in the big bang cosmology of the universe – if
dark matter dominates the mass of the universe, it ought to be in
models of the supposed Big Bang
 Dark matter becomes another free parameter in the Big Bang model
 Parameters can be manipulated to solve problems to make the theory
fit without any real ability to test the model