Gravitational lensing, Galaxies, and Galaxy Evolution Gravitational lensing, Galaxies, and Galaxy Evolution
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The OPTIONAL FINAL will be held: ***PAI 3.02 9am-noon Thursday, December 8th*** - ALL multiple choice, ~40 questions - Covers material of entire course Predicted Large Scale Structure of the Universe:
The Illustris Simulation — illustris-project.org Predicted Large Scale Structure of the Universe:
The Illustris Simulation — illustris-project.org Predicted Large Scale Structure of the Universe:
There are very large gravitationally bound structures consisting of groups and clusters of galaxies, strung together by filaments in the cosmic web. Predicted Large Scale Structure of the Universe:
There are very large gravitationally bound structures consisting of groups and clusters of galaxies, strung together by filaments in the cosmic web. Predicted Large Scale Structure of the Universe:
There are very large gravitationally bound structures consisting of groups and clusters of galaxies, strung together by filaments in the cosmic web. Galaxy Clusters are held together by huge concentrations of dark matter. Galaxy Clusters need dark matter, otherwise not gravitationally bound.
AMNH Astrovisualization Lab, Galaxy Cluster with and without Dark Matter. Galaxy Clusters need dark matter, otherwise not gravitationally bound.
AMNH Astrovisualization Lab, Galaxy Cluster with and without Dark Matter. The Bullet Cluster — Colliding Galaxy Clusters (!!!) best evidence for dark matter to-date (strongly disfavoring Modified Newtonian Dynamics, MOND) What effect does all of this MATTER have on what we see?
Let’s step back and look at this fabric of space we live in according to Einstein’s theory of General Relativity… What effect does all of this MATTER have on what we see?
Let’s step back and look at this fabric of space we live in according to Einstein’s theory of General Relativity… What effect does all of this MATTER have on what we see?
Let’s step back and look at this fabric of space we live in (according to Einstein’s theory of General Relativity)… What effect does all of this MATTER have on what we see?
Let’s step back and look at this fabric of space we live in (according to Einstein’s theory of General Relativity)… What effect does all of this MATTER have on what we see?
Let’s step back and look at this fabric of space we live in (according to Einstein’s theory of General Relativity)… What effect does all of this MATTER have on what we see?
Let’s step back and look at this fabric of space we live in (according to Einstein’s theory of General Relativity)… Locally, gravity (due to matter) keeps cosmic expansion in check: the galaxy is not getting bigger with time. Locally, gravity (due to matter) keeps cosmic expansion in check: the galaxy is not getting bigger with time.
More matter More substantial warping of spacetime
What happens when spacetime itself is curved due to gravity…
Light always travels in straight lines (when it doesn’t hit something and bounce off) What happens when spacetime itself is curved due to gravity…
Around massive objects, the path of light can be bent and affect what we see from Earth. What happens when spacetime itself is curved due to gravity…
Around massive objects, the path of light can be bent and affect what we see from Earth. What happens when spacetime itself is curved due to gravity…
Around massive objects, the path of light can be bent and affect what we see from Earth. What happens when spacetime itself is curved due to gravity…
Around massive objects, the path of light can be bent and affect what we see from Earth. What happens when spacetime itself is curved due to gravity…
Around massive objects, the path of light can be bent and affect what we see from Earth. What happens when spacetime itself is curved due to gravity…
Around massive objects, the path of light can be bent and affect what we see from Earth. What happens when spacetime itself is curved due to gravity…
Around massive objects, the path of light can be bent and affect what we see from Earth. What happens when spacetime itself is curved due to gravity…
What we see from earth is multiple images placing the galaxy in different parts of the sky… What happens when spacetime itself is curved due to gravity… Gravitational Lensing What happens when spacetime itself is curved due to gravity… Gravitational Lensing What happens when spacetime itself is curved due to gravity… Gravitational Lensing In this image of a galaxy cluster, can you mark where you think the cluster center is with an “X” and circle a few galaxies that are potentially gravitationally lensed images? x
In this image of a galaxy cluster, can you mark where you think the cluster center is with an “X” and circle a few galaxies that are potentially gravitationally lensed images? Gravitational Lensing can happen not just around galaxy clusters, but around galaxies as well (if there is close to perfect alignment) Gravitational Lensing can happen not just around galaxy clusters, but around galaxies as well (if there is close to perfect alignment) Gravitational Lensing can happen not just around galaxy clusters, but around galaxies as well (if there is close to perfect alignment)
The Cosmic Eye Gravitational Lensing can happen not just around galaxy clusters, but around galaxies as well (if there is close to perfect alignment)
The Cosmic Eye
The Cosmic Smiley Face/ Cheshire Cat Gravitational Lensing can happen not just around galaxy clusters, but around galaxies as well (if there is close to perfect alignment)
The Cosmic Eye
Einstein Cross
The Cosmic Smiley Face/ Cheshire Cat Gravitational Lensing can happen not just around galaxy clusters, but around galaxies as well (if there is close to perfect alignment)
The Cosmic Eye
Einstein Cross
The Cosmic Smiley Face/ Cheshire Cat
Einstein Ring Which galaxy in this image is closer to Earth? The blue one or the orange one?
Einstein Ring Which galaxy in this image is closer to Earth? The blue one or the orange one?
The orange (elliptical) galaxy.
Einstein Ring Which galaxy in this image is closer to Earth? The blue one or the orange one?
The orange (elliptical) galaxy.
Einstein Ring
If this orange, elliptical galaxy were more massive (or had more dark matter) what do you think would happen to the Einstein Ring? Discuss. Which galaxy in this image is closer to Earth? The blue one or the orange one?
The orange (elliptical) galaxy.
Einstein Ring
If this orange, elliptical galaxy were more massive (or had more dark matter) what do you think would happen to the Einstein Ring? Discuss. Which galaxy in this image is closer to Earth? The blue one or the orange one?
The orange (elliptical) galaxy.
Einstein Ring
If this orange, elliptical galaxy were more massive (or had more dark matter) what do you think would happen to the Einstein Ring? Discuss.
(a) it would stay the same (b) it would stay where it is but change in brightness (c) it would appear to be closer to the elliptical galaxy (i.e. smaller) (d) it would appear farther from the elliptical galaxy (i.e. bigger) (e) it probably wouldn’t be there anymore Which galaxy in this image is closer to Earth? The blue one or the orange one?
The orange (elliptical) galaxy.
Einstein Ring
If this orange, elliptical galaxy were more massive (or had more dark matter) what do you think would happen to the Einstein Ring? Discuss.
(a) it would stay the same (b) it would stay where it is but change in brightness (c) it would appear to be closer to the elliptical galaxy (i.e. smaller) (d) it would appear farther from the elliptical galaxy (i.e. bigger) (e) it probably wouldn’t be there anymore Which galaxy in this image is closer to Earth? The blue one or the orange one?
The orange (elliptical) galaxy.
Einstein Ring
If this orange, elliptical galaxy were more massive (or had more dark matter) what do you think would happen to the Einstein Ring? Discuss. mass ofgalaxy the lensing
4GM DLS ✓E = radius of Einstein 2 ring on the sky c DSDL (radians) r distances between observer,source lens, and Einstein Ring mass ofgalaxy the lensing
4GM DLS ✓E = radius of Einstein 2 ring on the sky c DSDL (radians) r distances between observer,source lens, and Einstein Ring note that: D = D + D S 6 LS L SN Refsdal: a multiply imaged supernova event
1998
z=0.54 (galaxy cluster) z=1.49 (galaxy with supernova) SN Refsdal: a multiply imaged supernova event
1998 First found in November 2014, and predicted to appear in a different image of the same galaxy sometime in 2015-2020. It reappeared in that image in December 2015!
z=0.54 (galaxy cluster) z=1.49 (galaxy with supernova) gravitational lensing in history… Gravitational lensing used as original evidence that Einstein was correct about general relativity.
Einstein’s 1919: Arthur Eddington observed position of background stars very close to big break! sun in sky during a solar eclipse, found they “moved” from normal position. Remember our planet unit???
this is a form of gravitational lensing! Remember our planet unit???
this is a form of gravitational lensing! SPIRALS An important note about spiral arms themselves:
without dark matter, one would think they would curl around and around to be very tightly packed: An important note about spiral arms themselves:
without dark matter, one would think they would curl around and around to be very tightly packed: An important note about spiral arms themselves:
without dark matter, one would think they would curl around and around to be very tightly packed: An important note about spiral arms themselves:
without dark matter, one would think they would curl around and around to be very tightly packed: An important note about spiral arms themselves:
without dark matter, one would think they would curl around and around to be very tightly packed: A sidenote about spiral arms themselves:
without dark matter, one would think This “spiraling in” pattern they would curl around and around doesn’t happen for two to be very tightly packed: reasons:
(A) Dark matter keeps the edges rotating FAST, but:
(B) The spiral arms themselves aren’t moving, it’s a density wave, like an intergalactic traffic jam This is called density wave theory. spiral arms do not move at the speed of the stars in them! This is called density wave theory. spiral arms do not move at the speed of the stars in them! One last word about these traffic jams from Phil Plait (Sorry if you’re sick of him! But this is really the best/only video about this on the internet)
Starts off talking about star-forming nebulae or gas clouds, not unlike the eagle nebula. Where are they mostly located in the galaxy? One last word about these traffic jams from Phil Plait (Sorry if you’re sick of him! But this is really the best/only video about this on the internet) One last word about these traffic jams from Phil Plait (Sorry if you’re sick of him! But this is really the best/only video about this on the internet) ELLIPTICALS ELLIPTICALS
Typically WAY MORE MASSIVE galaxies than spirals, stars are undergoing random motions like a swarm, and they aren’t forming new stars. ELLIPTICALS
knowing that elliptical galaxies are more massive than spiral galaxies what type of conclusions do you think you can draw about them (check all that apply)? _____ Ellipticals formed more quickly _____ Ellipticals formed more slowly _____ Ellipticals are older _____ Ellipticals are younger _____ Ellipticals are made up of mostly massive stars _____ Ellipticals are made up of mostly low-mass stars
Typically WAY MORE MASSIVE galaxies than spirals, stars are undergoing random motions like a swarm, and they aren’t forming new stars. ELLIPTICALS
knowing that elliptical galaxies are more massive than spiral galaxies what type of conclusions do you think you can draw about them (check all that apply)? _____x Ellipticals formed more quickly _____ Ellipticals formed more slowly _____x Ellipticals are older _____ Ellipticals are younger _____ Ellipticals are made up of mostly massive stars _____x Ellipticals are made up of mostly low-mass stars
Typically WAY MORE MASSIVE galaxies than spirals, stars are undergoing random motions like a swarm, and they aren’t forming new stars. ELLIPTICALS
knowing that elliptical galaxies are more massive than spiral galaxies what type of conclusions do you think you can draw about them (check all that apply)? _____x Ellipticals formed more quickly _____ Ellipticals formed more slowly _____x Ellipticals are older _____ Ellipticals are younger _____ Ellipticals are made up of mostly massive stars _____x Ellipticals are made up of mostly low-mass stars
Typically WAY MORE MASSIVE galaxies than spirals, stars are undergoing random motions like a swarm, and they aren’t forming new stars. SPIRALS ELLIPTICALS
Younger, active Older, no ongoing star-formation, star-formation, rotation dispersion dominated, less dominated, more massive massive Ways in which we quantify a galaxy’s qualities… morphology: size disk, irregular, stellar mass elliptical? SPIRALShalo mass ELLIPTICALS
star-formation Younger, active rate Older,metallicity no ongoing star-formation,gas mass star-formation, dust mass rotation redshift!! gas/dustdispersion dominated, less dominated,temperature more massive massive Ways in which we quantify a galaxy’s qualities… morphology: size disk, irregular, stellar mass elliptical? SPIRALShalo mass ELLIPTICALS
star-formation Younger, active rate Older,metallicity no ongoing star-formation,gas mass star-formation, dust mass rotation redshift!! gas/dustdispersion dominated, less dominated,temperature more massiveI could talk for a whole semester onmassive the complexities of measuring each one of these! Each is a puzzle, but we have cool tricks… in your free time you can work through Lecture Tutorials pages139-142 which talks about galaxy classification.
Ways in which we quantify a galaxy’s qualities… morphology: size disk, irregular, stellar mass elliptical? SPIRALShalo mass ELLIPTICALS
star-formation Younger, active rate Older,metallicity no ongoing star-formation,gas mass star-formation, dust mass rotation redshift!! gas/dustdispersion dominated, less dominated,temperature more massiveI could talk for a whole semester onmassive the complexities of measuring each one of these! Each is a puzzle, but we have cool tricks… There are also important related measurements on larger scales, for example:
1. cosmic star-formation rate density of the Universe, 2. cosmic stellar mass history of the Universe, 3. etc. There are also important 2 related measurements on larger scales, for example: 0.5
1. cosmic star-formation rate density of the Universe, 2. cosmic stellar mass history of the Universe, 3. etc. 22 41 5 150
58 270 Do these average properties of the Universe change with time? Do these average properties of the Universe change with time?
z 0.1 (1.3 billion⇠ years ago) Do these average properties of the Universe change with time?
z 0.1 z 1 (1.3 billion⇠ years ago) (7.6 billion⇠ years ago) Do these average properties of the Universe change with time?
z 0.1 z 1 z 3 (1.3 billion⇠ years ago) (7.6 billion⇠ years ago) (11.2 billion⇠ years ago) Do these average properties of the Universe change with time?
z 0.1 z 1 z 3 (1.3 billion⇠ years ago) (7.6 billion⇠ years ago) (11.2 billion⇠ years ago) Do these average properties of the Universe change with time?
z 0.1 z 1 z 3 (1.3 billion⇠ years ago) (7.6 billion⇠ years ago) (11.2 billion⇠ years ago)
Madau & Dickinson (2014) Do these average properties of the Universe change with time?
z 0.1 z 1 z 3 (1.3 billion⇠ years ago) (7.6 billion⇠ years ago) (11.2 billion⇠ years ago)
Present day
Madau & Dickinson (2014) Do these average properties of the Universe change with time?
z 0.1 z Cosmic1 z 3 (1.3 billion years ago) (7.6 billion years ago) (11.2 billion years ago) ⇠ “high⇠ noon” ⇠
Present day
Madau & Dickinson (2014) Do these average properties of the Universe change with time?
Cosmic dawn: first galaxies/ stars z 0.1 z Cosmic1 z 3 (1.3 billion years ago) (7.6 billion years ago) (11.2 billion years ago) ⇠ “high⇠ noon” ⇠
Present day
Madau & Dickinson (2014) Do these average properties of the Universe change with time?
Cosmic dawn: ?first galaxies/ stars z 0.1 z Cosmic1 z 3 (1.3 billion years ago) (7.6 billion years ago) (11.2 billion years ago) ⇠ “high⇠ noon” ⇠
Present day
Madau & Dickinson (2014) Cosmic Collisions! Comparing stars, galaxies and their environments. Milky Way Galaxy is 10kpc in radius and contains 300 billion stars. What do you think the average star’s size is? Comparing stars, galaxies and their environments. Milky Way Galaxy is 10kpc in radius and contains 300 billion stars. What do you think the average star’s size is?
recall the initial mass function
(the “IMF”) of stars…
# of stars
low-mass stars massive stars Comparing stars, galaxies and their environments. Milky Way Galaxy is 10kpc in radius and contains 300 billion stars. What do you think the average star’s size is?
recall the initial mass function
(the “IMF”) of stars… Average star in MW is 0.15 solar masses, happens to be # of stars 0.15 solar radii.
low-mass stars massive stars Comparing stars, galaxies and their environments. Milky Way Galaxy is 10kpc in radius and contains 300 billion stars.
What do you think the average star’s size is? R? =0.15 R h i Comparing stars, galaxies and their environments. Milky Way Galaxy is 10kpc in radius and contains 300 billion stars.
What do you think the average star’s size is? R? =0.15 R h i If you were to line up all the stars in the galaxy end- to-end how far would they reach? For reference: 1 R =6.96 105 km ⇥ 1pc=3.086 1016 m ⇥ Comparing stars, galaxies and their environments. Milky Way Galaxy is 10kpc in radius and contains 300 billion stars.
What do you think the average star’s size is? R? =0.15 R h i If you were to line up all the stars in the galaxy end- to-end how far would they reach? For reference: 1 R =6.96 105 km ⇥ 1pc=3.086 1016 m ⇥ Compared to the diameter of the galaxy how long would this chain of stars be? Comparing stars, galaxies and their environments. Milky Way Galaxy is 10kpc in radius and contains 300 billion stars.
What do you think the average star’s size is? R? =0.15 R h i If you were to line up all the stars in the galaxy end- to-end how far would they reach? For reference: 1 R =6.96 105 km ⇥ 1pc=3.086 1016 m ⇥ Compared to the diameter of the galaxy how long would this chain of stars be?
The Andromeda galaxy (our nearest large neighbor) is 0.67 Mpc from the Milky Way. How does the average distance between galaxies compare to their size? How does the average distance between stars compare to their size? Comparing stars, galaxies and their environments.
because the distance between stars is SO MUCH LARGER than their size, stars will almost NEVER collide with one another, but galaxies are relatively large compared to the distance between them, so they DO COLLIDE, *often*.