Astronomy & Physics Resources for Middle & High School Teachers
Gillian Wilson
http://www.faculty.ucr.edu/~gillianw/K12 A cosmologist is…..
….. an astronomer who studies the formation and evolution of the Universe.
Einstein An Observational Cosmologist uses Telescopes
Big Island, Hawaii Outline
Overview of NASA, NSF & Other Educational Links
Overview of cosmology and short summary of my research, with reference to State Standards Science Content Sections
EVERYTHING I will show / say today is linked to my webpage
http://www.faculty.ucr.edu/~gillianw/K12 In State Standards “Science Framework for California Public Schools”, Astronomy falls under Earth Sciences
Are there any Earth Sciences Teachers present?
Are there any General Science Teachers present?
Are there any Middle School Teachers present? http://www.faculty.ucr.edu/~gillianw/K12 http://www.faculty.ucr.edu/~gillianw/K12 http://www.faculty.ucr.edu/~gillianw/K12 Research (Observational Cosmology)
Gillian Wilson
http://www.faculty.ucr.edu/~gillianw State Standards G9-12
Physics 4: Waves
4e Students know radio waves, light and X-rays are different wavelength bands.
4f Students know how to identify the characteristic properties of waves: interference, diffraction, refraction, Doppler effect, and polarization.
http://www.faculty.ucr.edu/~gillianw State Standards G9-12
Earth Sciences 2: Earth’s Place in the Universe (Stars, Galaxies and the Universe)
2b Students know galaxies are made of billions of stars and comprise most of the visible mass of the universe. 2g Students know how the red-shift from distant galaxies and the cosmic background radiation provide evidence for the “big bang” model that suggest the universe has been expanding for 10 to 20 billion years.
http://www.faculty.ucr.edu/~gillianw State Standards G6-8
Grade 8 : Focus on Physical Sciences Standard Set 4: Earth in the Solar System (Earth Sciences)
4a Students know galaxies are clusters of billions of stars and may have different shapes. 4b Students know that the Sun is one of many stars in the Milky Way galaxy and that stars may differ in size, temperature and color. 4c Students know how to use astronomical units and light years as measures of distance between the Sun, stars and Earth.
http://www.faculty.ucr.edu/~gillianw Observational Cosmology
Dark Matter & Dark Energy
Very distant Clusters of Galaxies Galaxy Evolution
Extremely distant Quasars Structure Formation
Extremely Red Objects
Weak Gravitational Lensing Spitzer Space Telescope Infrared Studies
http://www.faculty.ucr.edu/~gillianw Observational Cosmology
Dark Matter & Dark Energy
Very distant Clusters of Galaxies Galaxy Evolution
Extremely distant Quasars Structure Formation
Extremely Red Objects
Weak Gravitational Lensing Spitzer Space Telescope Infrared Studies
http://www.faculty.ucr.edu/~gillianw Einstein & The General Theory of Relativity Einstein’s equations said that the Universe should be either expanding or collapsing.
He assumed that the Universe was static.
His fix - Add a constant term, the “cosmological constant” to cancel the effects of gravity on very large scales.
Einstein won the Nobel .. but not for Prize in 1921.. Relativity. Mount Wilson 100-inch (2.5m) Hooker Telescope
Largest Telescope in the World from 1917- 1948 Edwin Hubble Galaxy Distances and Radial Velocities
Hubble measured the distances to 24 nearby galaxies.
He also measured the spectra of these galaxies.
For each galaxy, identifiable features (elemental lines) appeared at longer wavelength than in lab.
The galaxy spectra were “redshifted”. Redshift
Emitted Spectrum
Observed Spectrum (lines shifted to longer wavelength)
Increasing Wavelength Galaxy Distances and Radial Velocities
Hubble measured the distances to 24 nearby galaxies.
He also measured the spectra of these galaxies.
For each galaxy, identifiable features (elemental lines) appeared at longer wavelength than in lab.
The galaxy spectra were “redshifted”.
Interpretation : Most galaxies moving away from our galaxy
The velocity was proportional to the distance to the galaxy. The Universe is Expanding !! Einstein & The General Theory of Relativity Einstein’s equations said that the Universe should be either expanding or collapsing.
He assumed that the Universe was static.
His fix - Add a constant term, the “cosmological constant” to cancel the effects of gravity on very large scales.
After Hubble discovered that the Universe was expanding, Einstein realized he had missed the opportunity to predict the expansion of the Universe. He called the cosmological constant his "greatest blunder." If the Universe is Expanding….
……… in the past, there must have been a “Big Bang” Evidence for Big Bang Discovery of Cosmic Background Radiation 1965
By accident !!
Narrowly scooping another group at Princeton (30 miles away) who had predicted the existence of the radiation, and had just finished building their own detector hoping to discover it.
Robert Wilson & Arno Penzias in front of 20-foot Horn Antenna, Bell Labs, Holmdel, New Jersey
1978 Nobel Prize to Penzias & Wilson 1990 CMB Measurement from COBE
The cosmic microwave background radiation has a blackbody spectrum with characteristic temperature T = 2.73K
2006 Nobel Prize to John Mather & George Smooth
Penzias & Wilson measured signal at one point/wavelength (7.35 cm) We know how the Universe began ….. ……… but we are not sure how it will end
Will it recollapse in Or will it continue to a “Big Crunch” ? expand forever resulting in a “Big Freeze” ? Clusters of Galaxies What is a Cluster of Galaxies?
Exactly what it sounds like!
Galaxies sometimes collect together, they “cluster”
The Universe is expanding and most galaxies are moving away from each other but there are some rare regions where hundreds or even thousands of galaxies are gravitationally bound together. The galaxies in these regions will stay close together for all time…. The Coma Cluster
The Coma cluster is named after the constellation in which it is found, Coma Berenices. Coma means “hair” in Latin. This is the nearest example of a rich (many galaxies) cluster. It is at a distance of 120,000,000 light years. 1933 Fritz Zwicky studied Coma cluster
Measured line-of-sight velocities for 8 galaxies.
Calculated mass of cluster from galaxy orbits. Using a different method calculated mass of cluster from sum of individual masses (using brightnesses) of galaxies. This value was much lower. Concluded that most (70-90%) of the mass in clusters was not associated with the galaxies.
It was invisible, or "dark matter".
His idea was ignored for 40 years until ... More Evidence for Dark Matter Gravitational Lensing
Hubble Space Telescope Image of A1689
Dark matter needed to lens galaxies “behind” cluster into spectacular giant arcs. Nature of Dark Matter? Dark Matter Candidates
MACHOS (MAssive Compact Halo ObjectS) Planets Things we know exist Faint stars But we don’t think there Black holes are enough of. WIMPS (Weakly Interacting Massive Particles) Barely interact with normal matter. Hard to detect. Theorists have proposed hundreds of different particles CERN LHC (Large Hadron Collider),Switzerland 2010 - Direct Searches Underground (to avoid cosmic rays) OR The Theory of Gravity could be Wrong on Large Scales?? How Much Dark Matter?
We didn’t find out until ~2000 From CMB anisotropies (see later) 1998 A Big Surprise Type Ia Supernovae (SNe)
In 1998, two teams of cosmologists independently discovered evidence that the rate of expansion of the Universe was speeding up with time. They were expecting to find that it was slowing down with time.
Both teams were studying Type Ia SNe Type Ia SNe occur when white dwarf star in binary system accretes matter from its companion, collapses & explodes.
Type Ia SNe have same “Tycho’s Nova”, remnant of Type Ia SNe maximum brightness which exploded in 1572 and convinced Tycho Brahe to become an astronomer. => “standard candles” Type Ia SNe
The white dwarf starts to steal mass from the larger star. When the white dwarf reaches a certain mass -- about 1.4 times the mass of our Sun -- the white dwarf becomes unstable, collapses, and then explodes! SNe fainter than expected
Fainter Best fit to data
Intrinsic luminosity known. Brighter Appear fainter than expected. Fainter => Must be further away than expected. => Distances Brighter larger than Distance expected. The Universe is Accelerating !!
The rate of expansion of the Universe is speeding up with time.
1998 “Science” Magazine “Breakthrough of the Year” 2011 Physics Nobel Prize for Discovery of Accelerating Universe A Mysterious Force is Pushing (cf gravity which is pulling) the Universe apart
“Dark Energy” At some time in the past, the Universe should have stopped Decelerating and begun Accelerating
Can we find evidence for this? 2004 The Cosmic Jerk
Happened 5 billion years ago.
Distance/Time Nature of Dark Energy Einstein & The General Theory of Relativity Einstein’s equations said that the Universe should be either expanding or collapsing.
He assumed that the Universe was static.
His fix - Add a constant term, the “cosmological constant” to cancel the effects of gravity on very large scales.
After Hubble discovered that the Universe was expanding, Einstein realized he had missed the opportunity to predict the expansion of the Universe. He called the cosmological constant his "greatest blunder.”
1998 The cosmological constant is back. Maybe Nature of Dark Energy?
Smoothly distributed through space (Does not clump together under influence of gravity).
May not be constant.
Some theories propose dark energy evolves with time growing stronger “Big Rip” or even reversing sign “Big Crunch”. Fate of the Universe?
We will assume dark energy is constant. Measurement of CMB Anisotropies 1990 - 2011 Fossilized imprint of the infant Universe, 380 000 years after the Big Bang.
Red and blue show warmer and cooler patches (more or less dense regions) that correspond to the seeds from which galaxies and clusters grow. By calcula ng what condi ons were like in the primordial fireball, cosmologists find that in a flat universe, the dominant “hot spots” in the cosmic background radia on should have an angular size of about 1° To determine the curvature, all they had to do was measure what size the hot spots appeared (whether parallel light rays were bent toward each other, away from each other, or not bent at all) A Way to Determine the Curvature of the Universe : Bending of Light Rays from CMB “hot spots”
If the universe is closed, If the universe is flat, If the universe is open, light rays from opposite light rays from opposite light rays from opposite sides of a hot spot bend sides of a hot spot do not sides of a hot spot bend toward each other … bend at all … away from each other …
… and as a result, the hot … and so the hot spot … and as a result, the hot spot appears to us to be appears to us with its true spot appears to us to be larger than it actually is. size. smaller than it actually is. COBE couldn’t make this measurement Earth
COBE’s resolution was only about 7° so it saw a “smeared” Earth viewed with same map of CMB anisotropies angular resolution as COBE 2000 Boomerang Telescope “The Goldilocks Game”
Anisotropies observed by Boomerang
Three geometries
Closed Flat Open Universe Universe Universe 2000 Boomerang Telescope “The Goldilocks Game”
Anisotropies observed by Boomerang
Three geometries
What BOOMERANG, MAXIMA & WMAP measured Hot spots measured to be 1° in size. Curvature very close to zero => Universe is flat (or very nearly so) The Content of the Universe (from CMB, SNe and Other Measurements)
Universe age = 13.7 billion years
Universe age = 380 thousand years Fate of the Universe
Red Line Galaxies will move further and further apart. They will gradually run out of gas to form new stars.
The existing stars will start to run out of fuel and die. The Fate of the Universe
Not all cosmologists believe this result though. Much more research is needed. I study Clusters of Galaxies Clusters of galaxies are the largest regions in the Universe held together by gravity. The galaxies in clusters don’t move away from each other. Clusters contain anywhere from 50 to1000 galaxies, plus dark matter and gas.
If we can count how the number of massive clusters changes with time, we can predict how the Universe will end. The Coma Cluster WMAP Science Team Clusters form from regions of the Universe which are very slightly overdense when the Universe is young.
Coma (NOAO/AURA/NSF) As you look at more and more distant objects e.g., galaxies, clusters of galaxies, you are looking back in time Hubble Space Telescope optical image of a cluster as it appeared 2.1 billion years ago Spitzer Space Telescope infrared image of a cluster as it appeared 8.9 billion years ago A massive SpARCS cluster observed with Spitzer Space Telescope when Universe was only 4.8 billion years old This cluster image is blurrier than Hubble Space Telescope image. Foreground stars in Milky Way Galaxy
These 30 - 50 red galaxies make up the cluster.
We can tell from their velocities (Doppler shift) that they are gravitationally bound.
We can also tell from their red colors that galaxies in this 14 M = (9.4 ± 6.2) ×10 MSun cluster are already very old.
http://www.faculty.ucr.edu/~gillianw
I lead the largest survey in the world designed to find young, distant clusters
I started the survey “SpARCS” in 2005. My team now numbers 25 people based all around the world.
We have found 200 new very distant clusters. 7.2 billion years ago
Examples of new clusters
8.9 billion years ago The SpARCS Survey largest every survey of very distant (< 6 billion years old) Clusters of Galaxies
200 new cluster candidates!
These will be used to study galaxy evolution. They will also be used measure the amount of dark matter & dark energy in the universe (by counting number of clusters as a function of mass at each epoch). Questions?
http://www.faculty.ucr.edu/~gillianw