What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms Type Ia Supernovae Progenitor Systems
Cosmology Traci Johnson
Carleton College
February 10, 2012
1 Type Ia Supernovae Traci Johnson Contents
What is a Type Ia Supernova? 1 What is a Type Ia Supernova? White Dwarfs
Explosion Mechanisms 2 White Dwarfs Progenitor Systems Cosmology 3 Explosion Mechanisms
4 Progenitor Systems
5 Type Ia Supernovae and Cosmology
2 Type Ia Supernovae Traci Johnson Table of Contents
What is a Type Ia 1 What is a Type Ia Supernova? Supernova? History History of Supernovae SN Types Observational Types of Supernovae Characteristics Observational Characteristics White Dwarfs
Explosion Mechanisms 2 White Dwarfs Progenitor Systems Cosmology 3 Explosion Mechanisms
4 Progenitor Systems
5 Type Ia Supernovae and Cosmology
3 Type Ia Supernovae Traci Johnson Earliest Observations of Supernovae
earliest recorded in second century A.D.
What is a Type Ia named “guest stars” by ancient astrologers Supernova? History more recently named stella novae: Latin for “new star” SN Types Observational Characteristics White Dwarfs
Explosion Mechanisms
Progenitor Systems
Cosmology
(left) Crab nebula: remnant of SN recorded in A.D. 1054 by Chinese. (right) Remnant of SN recorded by Tycho Brahe in A.D. 1572. Image credit: APOD.
4 Type Ia Supernovae Traci Johnson Modern Observations of Supernovae
What is a Type Ia Supernova? History Fritz Zwicky (Caltech – 1930s) SN Types Observational coined the term “supernova” Characteristics White Dwarfs (1934, with Walter Baade) Explosion proposed SNe were explosions Mechanisms
Progenitor of massive stars Systems found 120 SNe on his own, Cosmology one co-discovery developed first classification system for SNe (with Rudolph Minkowski) Fritz Zwicky observing at Palomar Observatory with the 18-inch Schmidt telescope. Image credit: Swedish Morphological Society.
5 Type Ia Supernovae Traci Johnson Supernova Types
What is a Type Ia Supernova? History Minkowski-Zwicky classification scheme → spectra SN Types Observational Characteristics White Dwarfs
Explosion Mechanisms
Progenitor Systems
Cosmology
Image credit: Chem1 Virtual Textbook.
6 Type Ia Supernovae Traci Johnson Supernova Types
What is a Type Ia Supernova? History Type II: strong SN Types Observational hydrogen lines Characteristics White Dwarfs (absorption and
Explosion emission) Mechanisms
Progenitor Type I: no Systems hydrogen lines Cosmology Type Ia: silicon absorption Type Ib: helium absorption Type Ic: neither of the above
Example spectra from various Type I and Type II SNe. Image credit: McGraw-Hill.
7 Type Ia Supernovae Traci Johnson Host Galaxies of Type Ia Supernovae
Spiral galaxies Elliptical galaxies host to all SNe subtypes only host Type Ia SNe What is a Type Ia Supernova? high star-forming rate → no star formation → old, History SN Types more heavy-mass stars low-mass stars Observational Characteristics White Dwarfs
Explosion Mechanisms
Progenitor Systems
Cosmology
Spiral galaxy M33. Image credit: APOD. Elliptical galaxy M87. Image credit: APOD.
8 Type Ia Supernovae Traci Johnson Thermonuclear Supernovae thermonuclear detonations of white dwarf stars Type Ia
A New Classification of Supernovae
What is a Type Ia Supernova? New classification scheme → explosion mechanics History SN Types Core Collapse Supernovae Observational Characteristics White Dwarfs catastrophic collapse of massive stars at the end of their lives Explosion Type II Mechanisms Progenitor Type Ib (no H layer) Systems
Cosmology Type Ic (no H or He layers)
9 Type Ia Supernovae Traci Johnson A New Classification of Supernovae
What is a Type Ia Supernova? New classification scheme → explosion mechanics History SN Types Core Collapse Supernovae Observational Characteristics White Dwarfs catastrophic collapse of massive stars at the end of their lives Explosion Type II Mechanisms Progenitor Type Ib (no H layer) Systems
Cosmology Type Ic (no H or He layers)
Thermonuclear Supernovae thermonuclear detonations of white dwarf stars Type Ia
9 Type Ia Supernovae Traci Johnson consistent with the detonation of carbon-oxygen white dwarfs – all of the same mass!
Observational Characteristics of Type Ia SNe
What is a Type Ia Supernova? most luminous supernovae History 36 SN Types peak luminosity ∼ 10 W Observational Characteristics ∼ 5 billion times more luminous than the Sun! White Dwarfs extremely homogeneous – very small dispersion in peak Explosion Mechanisms luminosity
Progenitor Systems very rare – 1 SN Ia every 5 centuries per galaxy Cosmology spectra → highest producers of iron and intermediate mass elements
10 Type Ia Supernovae Traci Johnson Observational Characteristics of Type Ia SNe
What is a Type Ia Supernova? most luminous supernovae History 36 SN Types peak luminosity ∼ 10 W Observational Characteristics ∼ 5 billion times more luminous than the Sun! White Dwarfs extremely homogeneous – very small dispersion in peak Explosion Mechanisms luminosity
Progenitor Systems very rare – 1 SN Ia every 5 centuries per galaxy Cosmology spectra → highest producers of iron and intermediate mass elements
consistent with the detonation of carbon-oxygen white dwarfs – all of the same mass!
10 Type Ia Supernovae Traci Johnson Table of Contents
What is a Type Ia 1 What is a Type Ia Supernova? Supernova?
White Dwarfs Formation Central 2 White Dwarfs Conditions Chandrasekhar Formation Mass Limit Central Conditions Explosion Mechanisms Chandrasekhar Mass Limit Progenitor Systems Cosmology 3 Explosion Mechanisms
4 Progenitor Systems
5 Type Ia Supernovae and Cosmology
11 Type Ia Supernovae Traci Johnson Stellar Evolution: The Main Sequence
What is a Type Ia Supernova?
White Dwarfs Formation star: gravitationally-bound Central Conditions ball of gas Chandrasekhar Mass Limit struggles to maintain Explosion Mechanisms hydrostatic equilibrium
Progenitor gravity inward Systems gas and light pressure Cosmology outward main-sequence: hydrogen fusion in core (90% of lifetime)
Hertzsprung-Russell diagram: a still-shot of stellar evolution. Image credit: Encyclopedia of Science.
12 Type Ia Supernovae Traci Johnson Low-Mass Stellar Evolution
What is a Type Ia Supernova?
White Dwarfs Formation Central Conditions Chandrasekhar Mass Limit Explosion Mechanisms
Progenitor Systems
Cosmology
Evolution of a low mass star on the HR diagram. Image credit: Univ. of Cincinnati - Physics.
13 Type Ia Supernovae Traci Johnson White Dwarf Characteristics
What is a Type Ia Supernova?
White Dwarfs Formation Central Hot, dense cores of low-mass stars Conditions Chandrasekhar compact objects – mass of Mass Limit Explosion the Sun, size of the Earth! Mechanisms surface temperatures – Progenitor Systems 8000-50,000 K Cosmology composition – He, C, O, Ne, Mg (depends on star’s initial mass)
Sirius A and Sirius B (a white dwarf). Image credit: Wikipedia.
14 Type Ia Supernovae Traci Johnson What is the Central Pressure of a White Dwarf?
What is a Type Ia recall: P = ρgh for constant ρ and g Supernova?
White Dwarfs pressure gradient inside a star: Formation Central Conditions dP GMr 4 2 Chandrasekhar = ρg = −ρ = − πρ r (1) Mass Limit dr r2 3 Explosion Mechanisms r = radius inside star Progenitor Systems Mr = mass inside r Cosmology integrate pressure gradient from surface to center:
Z 0 4 2 2 2 2 Pcentral = − πρ rdr = πρ RWD (2) RWD 3 3
15 Type Ia Supernovae Traci Johnson What is the Central Pressure of a White Dwarf?
What is a Type Ia Supernova?
White Dwarfs Formation Central white dwarf parameters: MWD = 1.0 Msun, RWD = 1.0 Rearth, Conditions 4 3 Chandrasekhar ρ = MWD/ 3 πRWD , Mass Limit Explosion Mechanisms 22 −2 Pcentral = 3.8 × 10 N m Progenitor Systems
Cosmology roughly 1.5 million times the central pressure of the Sun!!! ideal gas pressure not enough to maintain hydrostatic equilibrium
16 Type Ia Supernovae Traci Johnson Electron Degeneracy Pressure
What is a Type Ia Supernova?
White Dwarfs pressure created when electrons are Formation forced into higher energy levels by Central Conditions quantum effects Chandrasekhar Mass Limit quantum wave functions start Explosion Mechanisms overlapping in the high density Progenitor environment Systems Pauli exclusion principle: no two Cosmology fermions allowed in the same quantum state Heisenberg uncertainty principle:
∆x∆px ≈ ~ (3) Energy level occupancy of a degenerate electron gas. Image credit: McGill University Physics.
17 Type Ia Supernovae Traci Johnson Electron Degeneracy Pressure
What is a Type Ia Supernova? from both quantum principles: White Dwarfs Formation Central 5/3 Conditions P ∝ ρ (4) Chandrasekhar Mass Limit Explosion no temperature dependence Mechanisms for a carbon-oxygen white dwarf: Progenitor Systems Cosmology P = 1.9 × 1022 N m−2
electron degeneracy pressure is sufficient for maintaining white dwarf hydrostatic equilibrium
18 Type Ia Supernovae Traci Johnson Mass-Volume Relationship
What is a Type Ia Supernova?
White Dwarfs Formation Central setting electron degeneracy pressure equal to central pressure: Conditions Chandrasekhar Mass Limit MWDVWD = constant (5) Explosion Mechanisms
Progenitor increase in mass → decrease in size of white dwarf Systems
Cosmology speed of electrons cannot exceed the speed of light fundamental limit for the mass of white dwarfs
19 Type Ia Supernovae Traci Johnson The Chandrasekhar Mass Limit of White Dwarfs
What is a Type Ia Supernova?
White Dwarfs Formation Central Conditions Chandrasekhar Mass Limit derived by Chandrasekhar in Explosion Mechanisms 1930, Nobel Prize 1983 Progenitor 1.4 M Systems Sun
Cosmology SNe Ia result from “sneaking up” on this limit
Subrahmanyan Chandrasekhar (1910-1995). Image credit: APOD.
20 Type Ia Supernovae Traci Johnson Table of Contents
What is a Type Ia 1 What is a Type Ia Supernova? Supernova?
White Dwarfs Explosion 2 White Dwarfs Mechanisms Nuclear Fusion Ejecta Shell Radioactive 3 Explosion Mechanisms Decay Progenitor Nuclear Fusion Systems Ejecta Shell Cosmology Radioactive Decay
4 Progenitor Systems
5 Type Ia Supernovae and Cosmology
21 Type Ia Supernovae Traci Johnson Step 1: Carbon Fusion
What is a Type Ia white dwarf mass reaches Chandrasekhar limit Supernova?
White Dwarfs carbon core of white dwarf is compressed Explosion temperature rises to allow for carbon fusion reactions Mechanisms 8 Nuclear Fusion (T = 6 × 10 K) Ejecta Shell Radioactive Decay remains compact due to degeneracy Progenitor Systems (20 4 12 12 10Ne + 2He Cosmology 6 C + 6 C → 24 (6) 12Mg + γ
α-particles to fuel further reactions α-elements: # of protons = # of neutrons likely to start as a deflagration: subsonic propagation
22 Type Ia Supernovae Traci Johnson Step 2: Oxygen Fusion
What is a Type Ia Supernova? 9 White Dwarfs heat from initial reactions raises temperature to 10 K Explosion Mechanisms oxygen fusion reactions begin Nuclear Fusion Ejecta Shell ( Radioactive 28 4 Decay 16 16 14Si + 2He 8 O + 8 O → 32 (7) Progenitor S + γ Systems 16
Cosmology explosive reaction, transitions to a detonation: supersonic propagation fusion creates all α-elements up to iron
23 Type Ia Supernovae Traci Johnson Nuclear Binding Energy
What is a Type Ia Supernova?
White Dwarfs iron-56 has highest Explosion Mechanisms binding energy per Nuclear Fusion Ejecta Shell nucleon → most stable Radioactive Decay fusion of lower mass Progenitor Systems elements is exothermic Cosmology fusion of iron and higher is endothermic iron is final product of Type Ia supernovae
Binding energy per nucleon. Image credit: Blaze Labs.
24 Type Ia Supernovae Traci Johnson What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms video from: Nuclear Fusion Ejecta Shell Radioactive Three-Dimensional Simulations of the Deflagration Decay Phase of the Gravitationally Confined Detonation Progenitor Systems Model of Type Ia Supernovae Cosmology Jordan et al. 2007
25 Type Ia Supernovae Traci Johnson Stage 1: Optically Thick Rise
What is a Type Ia Supernova? photosphere White Dwarfs
Explosion Mechanisms Nuclear Fusion shell very thick and opaque in Ejecta Shell Radioactive early stages – “optically thick” Decay Progenitor photosphere at edge, where light Systems can escape Cosmology increasing surface area → increasing luminosity shell
An optically thick shell.
26 Type Ia Supernovae Traci Johnson What is a Type Ia assume constant velocity v (typically ∼ 10, 000 km s−1) Supernova?
White Dwarfs r = vt (8) Explosion Mechanisms Nuclear Fusion Ejecta Shell flux f of energy from photons escapes through the surface area Radioactive 2 Decay 4πr Progenitor Systems luminosity of the shell L becomes
Cosmology L = fA = 4πfr2
L = 4πfv2t2 (9)
L ∝ t2
27 Type Ia Supernovae Traci Johnson Stage 2: Transition to Optically Thin
What is a Type Ia Supernova? photosphere White Dwarfs
Explosion Mechanisms shell expands and becomes less Nuclear Fusion Ejecta Shell dense and less opaque Radioactive Decay photosphere moves inward and Progenitor Systems energy escapes Cosmology shell composition revealed in spectra “peeling layers off of an onion” shell
Partially optically thick shell.
28 Type Ia Supernovae Traci Johnson Stage 3: Optically Thin
What is a Type Ia Supernova? photosphere White Dwarfs
Explosion Mechanisms Nuclear Fusion Ejecta Shell Radioactive shell becomes completely Decay Progenitor translucent Systems energy from fusion dissipates Cosmology quickly
shell
An optically thin shell.
29 Type Ia Supernovae Traci Johnson Type Ia Supernova Light Curves
light curve: brightness vs. time
What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms late light curve Nuclear Fusion Ejecta Shell declines at slower rate Radioactive Decay other forms of energy Progenitor Systems power remainder of
Cosmology light curve thermal radiation radioactive decay expansion affects thermal energy
Light curve typical SN Ia. Image credit: McGraw-Hill.
30 Type Ia Supernovae Traci Johnson Gas Thermodynamics
What is a Type Ia Supernova? First Law of Thermodynamics → dU = W + Q White Dwarfs adiabatic expansion → Q = 0,W = −P dV Explosion 3 Mechanisms equipartition theorem → U = 2 kT Nuclear Fusion Ejecta Shell ideal gas law → PV = NkT Radioactive Decay 3 Progenitor −P dV = kdT Systems 2 Cosmology V 3 T = − dV 2 dT integrate to get: VT 3/2 = constant (10)
31 Type Ia Supernovae Traci Johnson Adiabatic Expansion from a Compact Object
What is a Type Ia Supernova?
White Dwarfs
Explosion Type I SNe arise from small, Mechanisms objects Nuclear Fusion Ejecta Shell white dwarfs Radioactive Decay cores stripped of outer Progenitor layers Systems Cosmology shell expands significantly from original size temperature of gas falls due to adiabatic expansion An example adiabatic process shown on a pressure-volume diagram. Image credit: Wikipedia.
32 Type Ia Supernovae Traci Johnson Radioactive Decay
What is a Type Ia Supernova?
White Dwarfs
Explosion radioactive decay dominates over thermal energy in powering Mechanisms Nuclear Fusion late light curves of Type I SNe Ejecta Shell 56 Radioactive 26Fe is not an α-element Decay Progenitor 26 protons and 30 neutrons Systems nuclear reactions “overshoot” iron and produce 56Ni, which is Cosmology 28 radioactive weak nuclear force
33 Type Ia Supernovae Traci Johnson Radioactive Decay
What is a Type Ia Step 1: Nickel decays to Cobalt Supernova? half-life = 6.1 days White Dwarfs electron capture: Explosion Mechanisms 56 − 56 Nuclear Fusion 28Ni + e → 27Co + νe + γ (11) Ejecta Shell Radioactive Decay Step 2: Cobalt decays to Iron Progenitor Systems half-life = 77 days
Cosmology electron capture (81%):
56 − 56 27Co + e → 26Fe + νe + γ (12)
β+ decay (19%):
56 56 + 27Co → 26Fe + e + νe (13)
34 Type Ia Supernovae Traci Johnson What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms Nuclear Fusion Ejecta Shell Radioactive Decay Progenitor Systems
Cosmology
Light curve of SNe Ia shaped by radioactive decay of nickel and cobalt. Image credit: McGraw-Hill.
35 Type Ia Supernovae Traci Johnson Synthesized Nickel Mass
What is a Type Ia Supernova? White Dwarfs Arnett’s Law: energy released at peak = energy injected by Explosion Mechanisms radioactive decay Nuclear Fusion Ejecta Shell luminosity proportional to decay rate λ Radioactive Decay Progenitor dN Systems L ∝ = −λN (14) dt Cosmology more nickel → higher luminosity accounts for luminosity dispersion of SNe Ia
36 Type Ia Supernovae Traci Johnson Table of Contents
What is a Type Ia 1 What is a Type Ia Supernova? Supernova?
White Dwarfs
Explosion 2 White Dwarfs Mechanisms
Progenitor Systems 3 Explosion Mechanisms Orbital Mechanics Single- Degenerate Double- 4 Progenitor Systems Degenerate Looking for Orbital Mechanics Signatures Single-Degenerate Cosmology Double-Degenerate Looking for Signatures
5 Type Ia Supernovae and Cosmology
37 Type Ia Supernovae Traci Johnson Binary Systems
What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms white dwarfs require a binary Progenitor Systems companion to reach the Orbital Mechanics Chandrasekhar limit Single- Degenerate nearly half of all stars reside Double- Degenerate in binary systems Looking for Signatures close binary systems Cosmology responsible for Type Ia SNe
Binary system Albireo, the maize and blue “Carleton binary.” Image credit: Wikipedia.
38 Type Ia Supernovae Traci Johnson Roche Lobe Accretion
What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms
Progenitor Systems Orbital Mechanics Single- Degenerate Double- Degenerate Looking for Signatures Cosmology
Semi-detached binary with accretion. Image credit: Prentice Hall.
39 Type Ia Supernovae Traci Johnson Type Ia Supernova Progenitor Systems
What is a Type Ia Supernova? White Dwarfs What we know: Explosion Mechanisms binary of two low-mass stars Progenitor Systems more massive star forms C-O white dwarf Orbital Mechanics Single- Degenerate What we don’t know: Double- Degenerate nature of the donor star Looking for Signatures main sequence or red giant – single-degenerate Cosmology another white dwarf star – double-degenerate
40 Type Ia Supernovae Traci Johnson The Single-Degenerate Scenario
What is a Type Ia Supernova? White Dwarfs hydrogen from donor accretes Explosion Mechanisms onto white dwarf Progenitor total mass reaches the Systems Orbital Chandrasekhar mass → SN Ia Mechanics Single- Degenerate likely to develop novae Double- Degenerate fusion in degenerate Looking for Signatures hydrogen layer on white Cosmology dwarf surface progenitor system survives Artist’s conception of a single-degenerate outbursts progenitor system. Image credit: APOD.
41 Type Ia Supernovae Traci Johnson The Single-Degenerate Scenario
What is a Type Ia Pros Supernova? White Dwarfs binary systems like these are common Explosion Mechanisms novae are frequently observed Progenitor Systems Orbital Mechanics Single- Cons Degenerate Double- Degenerate narrow hydrogen emission would be expected Looking for Signatures Chandrasekhar mass might not be reachable Cosmology −4 accreted mass: 10 Msun −5 −4 ejected mass: 10 − 10 Msun does not produce observed SN rate in elliptical galaxies
42 Type Ia Supernovae Traci Johnson The Double-Degenerate Scenario
What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms orbit shrinks due to
Progenitor gravitational radiation Systems Orbital less massive star Mechanics Single- (larger radius) fills Degenerate Double- Roche lobe first Degenerate Looking for Signatures if total mass of system Cosmology exceeds Chandrasekhar limit → SN Ia Artist’s conception of a double degenerate progenitor system. Image credit: U-MN.
43 Type Ia Supernovae Traci Johnson The Double-Degenerate Scenario
What is a Type Ia Supernova?
White Dwarfs Pros
Explosion Mechanisms no hydrogen
Progenitor Systems double-degenerate systems have been found Orbital Mechanics Single- Degenerate Double- Cons Degenerate Looking for Signatures if accretion rate is too high: Cosmology no explosion accretion-induced collapse into neutron star
44 Type Ia Supernovae Traci Johnson How can we look for signs of the progenitor?
What is a Type Ia Supernova?
White Dwarfs Explosion set upper limits on the luminosity of the progenitor system Mechanisms
Progenitor archival images Systems early interaction with donor star Orbital Mechanics look for radio and x-ray emission Single- Degenerate Double- improve on setting upper limits Degenerate Looking for build more sensitive telescopes Signatures find closer supernovae – good luck! Cosmology
45 Type Ia Supernovae Traci Johnson Table of Contents
What is a Type Ia 1 What is a Type Ia Supernova? Supernova?
White Dwarfs Explosion 2 White Dwarfs Mechanisms
Progenitor Systems 3 Explosion Mechanisms Cosmology Standard Candles Cosmic Evolution 4 Progenitor Systems Acceleration
5 Type Ia Supernovae and Cosmology Standard Candles Cosmic Evolution Acceleration
46 Type Ia Supernovae Traci Johnson Standard Candles
What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms Inverse square law: Progenitor Systems L Cosmology F = 2 (15) Standard 4πd Candles Cosmic Evolution Standard candles Acceleration well-known intrinsic luminosity “Candles” further away appear distance markers dimmer. Image credit: Supernova Cosmology Project.
47 Type Ia Supernovae Traci Johnson Cosmic Distance Ladder
What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms
Progenitor Systems
Cosmology Standard Candles Cosmic Evolution Acceleration
The various techniques and standard candles astronomers use to measure different distance scales throughout the universe to great precision. Image credit: Encyclopedia of Science.
48 Type Ia Supernovae Traci Johnson Type Ia Supernovae as Standard Candles
Type Ia SNe as standard candles: bright, homogeneous What is a Type Ia Supernova? not perfect standard candles: luminosity dispersion White Dwarfs nickel mass scales light curves Explosion standardize light curves based on empirical stretch factor Mechanisms
Progenitor Systems
Cosmology Standard Candles Cosmic Evolution Acceleration
Applying the “stretch factor” to SNe Ia light curves. Image credit: Kim et al. 1997.
49 Type Ia Supernovae Traci Johnson A Brief History of Cosmology
What is a Type Ia Supernova?
White Dwarfs Albert Einstein proposed theory of general relativity – 1916 Explosion gravity: warping of spacetime by mass and energy Mechanisms predicts a universe that is either expanding or contracting, but Progenitor Systems always decelerating due to gravity Cosmology Standard Edwin Hubble’s discovers universal expansion – 1925 Candles Cosmic Evolution v = H◦d (16) Acceleration looking further back in time will reveal nonlinear Hubble relationship and the magnitude of universal deceleration
50 Type Ia Supernovae Traci Johnson Cosmology with Type Ia Supernovae
What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms Using SNe Ia to measure universal deceleration Progenitor luminosity distance = how long ago the the SNe erupted → time Systems redshift = size of universe when SNe erupted Cosmology Standard Candles gives scale size of universe as a function of time Cosmic Evolution data can be fitted to universal models to reveal composition and Acceleration ultimate fate of the universe
51 Type Ia Supernovae Traci Johnson Observations of High-Redshift Supernovae
1990s: Two teams competing teams of astronomers searched for SNe Ia at high-redshift to find universal deceleration rate What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms
Progenitor Systems
Cosmology Standard Candles Cosmic Evolution Acceleration
Competing project leaders Brian Schmidt (left) and Saul Perlmutter (right) “duke it out.” Image credit: Discover Magazine.
52 Type Ia Supernovae Traci Johnson A Surprising Discovery: Acceleration!
What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms
Progenitor Systems
Cosmology Standard Candles Cosmic Evolution Acceleration
The expansion history of the universe, provided by high redshift supernovae. Image credit: Supernova Cosmology Project.
53 Type Ia Supernovae Traci Johnson Nobel Prize in Physics 2011
... “for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.” - Royal What is a Type Ia Supernova? Swedish Academy of Science, 2011.
White Dwarfs
Explosion Mechanisms
Progenitor Systems
Cosmology Standard Candles Cosmic Evolution Acceleration
Image credit: Royal Swedish Academy of Science.
Supernova Cosmology Project Leader: Saul Perlmutter High-Z Supernova Team: Brian Schmidt and Adam Riess
54 Type Ia Supernovae Traci Johnson Where We Have Been
What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms discussed the physics SNe Ia Progenitor white dwarfs Systems explosion mechanisms Cosmology binary systems lingering question: what are the progenitor systems? learned how we can use SNe Ia to study the universe
55 Type Ia Supernovae Traci Johnson SN 2011fe: The Brightest SN Ia in 25 Years
erupted August 24th, 2011 in M101 in Pinwheel galaxy closest Type Ia supernova in 25 years! What is a Type Ia Supernova? beginning to answer outstanding questions about SNe Ia White Dwarfs Images from Goodsell Observatory, Carleton College: Explosion Mechanisms
Progenitor Systems
Cosmology
June 9, 2009 September 30, 2011 October 13, 2011 Alex Dixon Andrea Vang Traci Johnson Marlea Iiams Puja Patel Aurora Roth Prof. Cindy Blaha Andrea Vang
56 Type Ia Supernovae Traci Johnson Acknowledgements
What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms Faculty advisor: Cindy Blaha Progenitor Systems Peer advisor: Valerie Fox Cosmology Department of Physics and Astronomy All of you!
57 Type Ia Supernovae Traci Johnson SN 2011fe: Timeline of Events
What is a Type Ia Supernova? White Dwarfs August 24, 2011: transient discovered in Pinwheel galaxy Explosion Mechanisms (M101) by the Palomar Transient Factory Progenitor Systems early spectroscopy revealed high-velocity oxygen, calcium, and
Cosmology silicon – classified as Type Ia SN from fireball expansion model, event was thought to be discovered only 4 hours after initial outburst follow-up daily spectroscopy and photometry by numerous observatories covering different wavelength regimes
58 Type Ia Supernovae Traci Johnson What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms
Progenitor Systems
Cosmology
Daily photometry of Image credit: RIT Observatory.
59 Type Ia Supernovae Traci Johnson Early Results
What is a Type Ia Supernova? White Dwarfs spectroscopy and photometry (Nugent et al. 2011) Explosion Mechanisms consistent with compact object < 0.1 R Progenitor no collision with donor star Systems
Cosmology archival image search – no red dwarf companion (Li et al. 2011) Hubble Space Telescope in optical Spitzer Space Telescope in infrared no detection in the radio (Chomiuk et al. 2012) Expanded Very Large Array
60 Type Ia Supernovae Traci Johnson What is a Type Ia Supernova?
White Dwarfs
Explosion Mechanisms
Progenitor Systems
Cosmology
Spitzer and EVLA images of SN 2011fe, showing non-detections. Image credit: Chomiuk et al. 2012.
61 Type Ia Supernovae Traci Johnson What can we learn from SN 2011fe?
What is a Type Ia Supernova? regarding the nature of SNe Ia: White Dwarfs best upper limits on progenitor system ever Explosion Mechanisms likely from a double-degenerate system
Progenitor consistent with models of white dwarf detonation Systems however, it does not speak for ALL SNe Ia Cosmology regarding the state of observational astronomy: astronomy, and all science in general, is becoming more collaborative global networking will make SN 2011fe most-well studied SN Ia to date relevant for all astronomical transients (i.e. core-collapse SN, novae, gamma-ray bursts)
62 Type Ia Supernovae Traci Johnson Einstein’s Cosmological Constant Resurrected
What is a Type Ia Supernova?
White Dwarfs
Explosion dark energy: the source of negative Mechanisms pressure driving the acceleration Progenitor Systems cosmic microwave background Cosmology (CMB) independently supports the presence of dark energy SNe, CMB, and baryon acoustic oscillations (BAO) all overlap
∼ 72% dark energy (ΩΛ) ∼ 27% matter (Ωm); 23% dark, 4% baryonic
Ωm and ΩΛ confidence interval contours. Image credit: Supernova Cosmology Project.
63 Type Ia Supernovae Traci Johnson