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July 26, 2004
Part I: Galaxies and Galaxy Evolution
Part II: Clusters of Galaxies and Large Scale Structures
July 26, 2004
July 26, 2004
Exploring the Interstellar Medium Debrief
• What is the interstellar medium?• What do we know about its number
density?• What do we know the temperature of
the ISM?• What do we know about its heat?• What is the difference between heat
and temperature?• Did you prove this?
July 26, 2004
Exploring the Interstellar Medium Debrief
• What is the Local Bubble, and what are some possibilities for how it formed?
• What do we know now about the event and objects in our Universe?
• What else do we know?
Now lets move farther out…
• What is a galaxy?
July 26, 2004
Now lets move farther out…
• What do we know about galaxies?
• How do they evolve or form?
• Why do they form?
• How do we know?
• Prove it!
• What do our students need to know about galaxies?
July 26, 2004
Hidden Lives of Galaxies
• Read the first 2 pages of the handout
• Get into six groups of four
• Every group must have access to a wall with a poster
• Use the poster the answer the questions that are asked on the handout. (page 6)
July 26, 2004
M31/Andromeda
• Our nearest spiral neighbor
• 2 million light years away
Center of M31 has two optical nuclei
July 26, 2004
M31/Chandra X-ray
• Image of central part of our neighbor M31
• Bright X-ray sources are binaries with black holes or neutron stars
• Central BH is very cool, 30 million Mo
Center of M31
July 26, 2004
Edge-on Spiral Galaxy
• NGC 891 - we think our Galaxy looks like this
This is an infrared
composite image from
KPNO
July 26, 2004
Starburst galaxies
• Galaxies which are undergoing rapid phase of star formation
• Supernova rate about 10 times higher• Many bright stars• Fluorescent gas clouds• GRBs are in burst region.
NGC 4214HST
July 26, 2004
Starburst Galaxy M82• Radio map is CO
which traces H• IR map shows
proto-stars
Radio
IR
July 26, 2004
Starburst galaxy M82
• X-ray evidence for intermediate mass black hole in M82
• High supernova rate makes many smaller black holes, which may merge
July 26, 2004
Hidden Lives of Galaxies
In the same groups as before…
• Read page 7
• Read and follow the instructions on page 8
July 26, 2004
The Hubble Fork Diagram
July 26, 2004
July 26, 2004
Galaxy Formation movie
• Formation of galaxies in universe
July 26, 2004
Hidden Lives of Galaxies
Once again in your same groups…• Read page 9• Ok now based on all of the characteristics of
the different types of galaxies. Now it is your turn to match the unusual galaxies with the names on the right. (page 10) Make sure you give reasons why you choose the name.
• Continue reading pages 11-12, 13,and 22.
July 26, 2004
Break
• Which came first, the galaxy or its central black hole?
July 26, 2004
Active Galaxies• Now get into groups and lets talk about the
GLAST Active Galaxies Poster• Discussion topics:
– What is it explaining?– Why does science care?– How do these objects “fit in”?– What is the scientific evidence for these objects?– What are the of the different objects on this
poster?– Similar and dissimilar characteristics?
July 26, 2004
An Active Galaxy Journey
July 26, 2004
Unified Model of AGN
• All AGN are the same: central BH plus disk and jets
• Differences in lines, jets, & spectra are due to different viewing angles
• Also possible that BHs are being fed at different rates
July 26, 2004
Galaxies and Black Holes
• Zooming in to see the central torus of an Active Galaxy.
Jet
Accretion disk
Black Hole
July 26, 2004
Radio Lobe Galaxy
Radio lobes (Q-tips)
Jet
Accretion Disk
July 26, 2004
Two Views of an Active Galaxy
View at an angle to jetView at 90 from Jet
Radio Lobe Galaxy Seyfert Galaxy
July 26, 2004
Seyfert Galaxy NGC 7742• Bright nucleus• 3000 light years across• 72 million light years away HST
July 26, 2004
Centaurus A/Optical
• Giant elliptical galaxy
• 10 million light years away
• Dark dust lane obscures the central region
July 26, 2004
Centaurus A/Radio
• Double Lobe Radio Galaxy
• Image shows radio lobes superposed on optical image
• Central black hole must be producing radio jets and lobes
July 26, 2004
Centaurus A/X-ray
• X-ray image from Chandra
• Bright nucleus can be seen in center at location of black hole
• Small jet to lower right ends in shocked region
July 26, 2004
Centaurus A/IR• IR map shows a
second galaxy (barred spiral) hiding inside Cen A’s dust lanes
• Elliptical’s gravity helps barred spiral maintain its shape
• Material funneled along the spiral's bar fuels the central black hole which powers the elliptical's radio lobesSymbiotic relationship
July 26, 2004
M87 Optical
• Giant elliptical galaxy• At center of Virgo
cluster• Many globular clusters
surround it• Little dust and gas in the
galaxy• 50 million light years
away
July 26, 2004
M87 HST Movie
July 26, 2004
M87 Optical Jet
• HST IR and UV composite
• Globular clusters also seen
• Note shock waves and knot patterns in jet
• Bright point at central black hole
July 26, 2004
M87 Radio Jet
• Central black hole is making jets
• Jets are making bubbles of hot gas
• Bubbles are as big as 200,000 light years
• Smallest resolution VLBI image is 0.2 light years
July 26, 2004
M87 X-ray and radio
• X-ray contours on radio image
• High energy emission from central black hole
• ROSAT X-ray data
July 26, 2004
Another view of an Active Galaxy
Looking down the Jet
From this view, we see the Active Galaxy emitting gamma rays and X-rays.
Blazar GalaxyQuasar 3C279
July 26, 2004
Gamma-ray Quasars
• 3C 279 is a very bright, repeatedly flaring gamma-ray source, seen at MeV - TeV energies
3C273 is much
brighter at optical
energies
3C279
3C273
July 26, 2004
Blazar movie
• Shows rotating black hole in the center of Active Galaxy, which is emitting relativistic jets of material
• Blazar is a quasar that is aiming its beams directly at us
July 26, 2004
Most distant QSOs• Redshift record is now around Z=6.5• Sloan Digital Sky Survey
Z = 5.0 Z = 4.75Z = 4.9
July 26, 2004
Galaxy Collision
July 26, 2004
Galaxy Collisions, Part 2
July 26, 2004
Cartwheel Galaxy• Wheel shape was
formed from collision of two galaxies
• Bright stars are forming at the edges of the wheel (105 light years in diameter)
• Intruder galaxy is no longer visible
This is from HST
July 26, 2004
How the Galaxy got its jets
July 26, 2004
Active Galaxies and Jets
• What do Active Galaxies look like when viewed from different distances?
July 26, 2004
Reflection and Debrief
• Now what do we know?
• What are the big ideas here?
• What do our students need to know?
• Is there anything else we need to know?
• Misconceptions
(take notes)
July 26, 2004
Reflection and Debrief
• What are some effective ways to teach students about galaxies and how they evolve?
• Standards???
(take notes)
July 26, 2004
Break
• Which came first the galaxy or the clusters?
July 26, 2004
Engage
• Examine the photograph of the Hubble Deep Field and the histogram of galaxies
• Fill out the worksheet
• Demo of the CLEA Wedge activity
• CLEA wedge plots
July 26, 2004
Wedge Plot Activity
• These data are from CLEA’s LSS lab
• Plot them on the wedge plot
• How many clusters do you see?
• Why is the wedge plot a better representation of the measurements than the linear plot?
July 26, 2004
“Stickman”
• “Slice” –style Redshift survey pioneered by Margaret Geller, Marc Davis and John Huchra
Distance is plotted vertically as given by redshifts
The body of the stickman is due to the Coma cluster
His arms form “walls”
July 26, 2004
Las Campanas Survey Done by Shectman et al. Largest redshift survey Clearly shows walls and voids 75-80% of space is devoid of bright galaxies Typical distance between 2 galaxies is around 7.5 Mpc Typical distance
between 2 clusters is around 20 Mpc
July 26, 2004
Clusters of Galaxies
• Clusters of galaxies are the largest gravitationally bound systems in the universe, with sizes of a few Mpc (a Mpc is about 3 million light-years).
• A typical cluster contains hundreds or thousands of galaxies
• Most of the mass is in the form of a hot intracluster gas, which is is heated to high temperatures (106-108K or several keV)
• Clusters are rare objects: fewer than 1 in 10 galaxies in the universe resides in clusters
July 26, 2004
Types of Galaxy Clusters• Regular clusters
– concentrated central core – well-defined spherical structure– often dominated by a giant galaxy – usually quite rich, M~1015 Mo
– most galaxies are elliptical or lenticular
• Irregular clusters– no well-defined center– ~half the galaxies are spirals– Often contain subclusters– Probably not steady state
July 26, 2004
Distances to Galaxy Clusters
• Going beyond Cepheid Variables to the next rungs on the Cosmic Distance Ladder
• Brightest Cluster Galaxies: The brightest galaxy in a cluster of galaxies has been used as a standard candle.
• But: rich clusters with many galaxies will probably have the most luminous galaxies even though these galaxies are very rare, while the brightest galaxy in less rich clusters are probably not as bright
July 26, 2004
X-ray emission from Clusters Gas in clusters of galaxies is held by mass where:
Mass of hot gas is more than 3 times the mass of the visible light galaxies in the Virgo cluster Strongest X-rays are around M87
Virgo/ROSAT
M = V2R
G
July 26, 2004
Cluster Formation
• Formation and evolution of a galaxy cluster (from T6 group at Los Alamos)
Evolution of a Cd galaxy cluster (from John Dubinski at CITA)
movies
July 26, 2004
Galaxy Harassment
• Spirals merge to form ellipticals• Biggest elliptical cannibalizes the others
to form one giant elliptical in the center of the cluster
• Dwarf ellipticals are formed by harassment (high velocity encounters) of low-mass spirals
• Detectable arcs of debris are left over – providing fuel for quasars
July 26, 2004
Virgo cluster of galaxies The Virgo cluster of galaxies is about 65 million light years away It contains about 2500 galaxies It is dominated by M87
M87
July 26, 2004
Virgo Cluster• It is the nearest rich cluster of galaxies • Classification - irregular • Covers about 100o of sky or at its distance it
spreads out over tens of millions of light years • Recessional velocity is about 0.3% of velocity of
light • X-ray emission concentrated around individual
galaxies, particularly M84 and M86• The strong radio galaxy M87 in the Virgo cluster
is also a strong source of X-rays
July 26, 2004
Perseus Cluster One of the closest galaxy clusters at a distance of 300 million light years Part of the Perseus Pisces supercluster which is 15 degrees across and has over 1000 galaxies
July 26, 2004
Hydra Cluster Distance of 840 million light years Several hundred galaxies in the cluster 35 million degree gas in center rising to 40 million in the outside Several million light years across the gas cloud
Optical/La Palma
July 26, 2004
Hydra Cluster
Radio/NRAO
X-ray/Chandra
July 26, 2004
Coma Cluster Coma cluster has about 1000 galaxies It is located near the north galactic pole It is about 250 million light years away (80 Mpc) Large bright central cluster is merging with smaller galaxy group at the lower right 3 Mpc
July 26, 2004
Small Cluster
X-rays from this smaller cluster were discovered by ROSAT Hot gas engulfs the two bright elliptical galaxies It is about 500 million light years away
July 26, 2004
Very Distant Cluster
This is a very red cluster, located at Z~1 It is the most distant cluster discovered by HST It may be too far away to have formed in a dense universe
July 26, 2004
Very Distant Cluster
This cluster is 8 billion light years away, so it formed when the universe was half its present age It is also very red It should not exist if the Universe is dense
July 26, 2004
How clusters affect galaxy evolution
• Ram pressure and turbulent stripping of gas from a spiral galaxy as it falls through the hot ICM of a rich galaxy cluster (by Vicent Quilis with Ben Moore)
• The galaxy model is 3d with a stellar disk, bulge + dark matter halo. The colours show the gas density in a thin slice centered on the disk
movie
July 26, 2004
Merging Clusters A2142 cluster The 50 million degree gas is coolest in the center where two clusters have finished merging The gas outside the center is 100 million degrees – heated by the collision Chandra image
July 26, 2004
Cannibal Cluster
A3827 is about 1.5 billion light years away The central dominant galaxy is eating five smaller galaxies
ESO/Optical
July 26, 2004
Large Scale Structure
• Distribution of matter in the Universe on scales at or above 10 Mpc
• Can be determined by– Galaxy surveys– Lyman-alpha forest studies– Quasar clustering studies
• Superclusters are largest structures seen – but they are not gravitationally bound
July 26, 2004
Local Supercluster
The Local supercluster contains the Virgo cluster of galaxies as well as about 50 galaxy groups
July 26, 2004
Superclusters
• Superclusters usually have 3-10 clusters of galaxies
• They are not gravitationally bound
• Our local supercluster contains the Virgo cluster (at 16 Mpc) and extends about 40- 50 Mpc
Local Supercluster
July 26, 2004
Walls and Voids
• Universe looks like soap bubbles in 3D• Galaxies occur on the bubble surfaces• Superclusters are formed where bubbles merge• Walls are made of elongated superclusters – the
largest is the “Great Wall” - about 100 Mpc in length at a distance of 100 Mpc
• Voids are about 100 Mpc in diameter – are 90% of space
• Clusters of galaxies are bright spots on the walls
July 26, 2004
Flyby universe movie
• Las Campanas data – notice the walls and voids as you fly by
July 26, 2004
Formation of Large Scale Structure
• Simulation by Martin White shows the evolution of structure starting with fluctuations in the Cosmic Microwave Background
movie
July 26, 2004
The End of Greatness
• Most recent surveys are so large that the largest structures (about 100 Mpc) are smaller than the survey size
• This is a 200 Mpc simulation from Ben Moore (using CDM)
July 26, 2004
Where are we going?
The Milky Way Galaxy is falling towards the Virgo cluster at ~300 km/s The Virgo cluster is falling towards the Hydra-Centaurus supercluster also at ~300 km/s
But the Hydra-Centaurus cluster is also falling towards something…..
July 26, 2004
Great Attractor
~1016 solar masses concentrated 65 Mpc away in the direction of Centaurus
Abell 3627 near the Great Attractor
The “Great Attractor” seems to be pulling in the Hydra-Centaurus super-cluster
But only 10% that amount of visible matter can be seen!
July 26, 2004
What do we know about our Universe?
• Using the chart found on page 23 of the handouts fill in the blanks to all the components of a galaxy.
• What do we know about the Universe now?
July 26, 2004
Reflection and Debrief
• Now what do we know?
• What are the big ideas here?
• What do our students need to know?
• Is there anything else we need to know?
• Misconceptions
(take notes)
July 26, 2004
Reflection and Debrief
• What are some of the effective ways to teaching these topics?
• Standards???
(take notes)
July 26, 2004
Web Resources (galaxies)
• A. Ptak’s intermediate mass black hole in M82 http://astro.phys.cmu.edu/~ptak/m82/
• T. di Matteo’s X-ray quiet AGN http://www-glast.sonoma.edu/HEADmeeting/tuesday/index.html
• ROSAT X-ray images http://wave.xray.mpe.mpg.de/rosat/calendar/2000/oct
• NCSA’s Unveiling the Hidden Universe http://www.ncsa.uiuc.edu/Cyberia/Bima/BimaHome.html#Unveiling
July 26, 2004
Web Resources (galaxies)
• Astronomy picture of the Day http://antwrp.gsfc.nasa.gov/apod/astropix.html
• Imagine the Universe http://imagine.gsfc.nasa.gov
• M87 radio images http://www.aoc.nrao.edu/~fowen/M87.html
• Space Telescope Science Institute http://stsci.edu
• Sloan Digital Sky Survey http://www.sdss.org/
July 26, 2004
Web Resources (galaxies)
• NCSA M82 images http://www.ncsa.uiuc.edu/Cyberia/Bima/ExtraGal.html
• Galaxy Formation Movie from NCSA http://www.ncsa.uiuc.edu/Cyberia/Cosmos/TheWorksMovies.html
July 26, 2004
Web Resources (LSS)
• On-line Journey through Astronomy http://csep10.phys.utk.edu/astr162/lect/gclusters/attractor.html
• J. C. Evans Astronomy 103 Course http://www.physics.gmu.edu/classinfo/astr103/CourseNotes/Html/Lec08/Lec08_pt1_universeClusters.htm
• Martin White’s Large Scale Structure http://astron.berkeley.edu/~mwhite/probes-lss.html
• XMM-Newton Large Scale Structure Survey http://vela.astro.ulg.ac.be/themes/spatial/xmm/LSS/First/FMos/index_e.html
July 26, 2004
Web Resources (LSS) Ned Wright’s ABCs of Distance http://www.astro.ucla.edu/~wright/distance.htm
Ray White’s Cluster of Galaxies Mug Shots http://www.astr.ua.edu/white/mug/cluster/clusters.html
Cambridge Cosmology Pages http://www.damtp.cam.ac.uk/user/gr/public/gal_lss.html
Greg Bothun’s Cosmology Book http://nedwww.ipac.caltech.edu/level5/Bothun2/Bothun_contents.html
J. Cohn’s Lyman alpha Forest pages http://astron.berkeley.edu/~jcohn/lya.html
July 26, 2004
Web Resources (LSS)
T-6 Group at LANL animations and picture http://qso.lanl.gov/pictures/Pictures.html
John Dubinski’s Big cluster simulations http://www.cita.utoronto.ca/~dubinski/bigcluster.html
2DF redshift survey project http://www.2dfquasar.org/
Ben Moore’s N-body simulations
http://star-www.dur.ac.uk/~moore/movies.html