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 Prize in 1921.... but not for 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 a Big Crunch? Or will it continue to 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 Faint stars Black holes Things we know exist But we don t think there 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. Tycho s Nova, remnant of Type Ia SNe which exploded in 1572 and convinced Tycho Brahe to become an astronomer. Type Ia SNe have same maximum brightness => 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 Brighter Fainter Brighter Distance Intrinsic luminosity known. Appear fainter than expected. => Must be further away than expected. => Distances larger than 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, light rays from opposite sides of a hot spot bend toward each other If the universe is flat, light rays from opposite sides of a hot spot do not bend at all If the universe is open, light rays from opposite sides of a hot spot bend away from each other and as a result, the hot spot appears to us to be larger than it actually is. and so the hot spot appears to us with its true size. and as a result, the hot spot appears to us to be smaller than it actually is.
COBE couldn t make this measurement Earth COBE s resolution was only about 7 so it saw a smeared map of CMB anisotropies Earth viewed with same angular resolution as COBE
2000 Boomerang Telescope The Goldilocks Game Anisotropies observed by Boomerang Three geometries Closed Universe Flat Universe Open 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. M = (9.4 ± 6.2) 10 14 M Sun We can also tell from their red colors that galaxies in this 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