The Stellar Graveyard

Northeastern Illinois University

Greg Anderson Department of Physics & Astronomy Northeastern Illinois University

Fall 2019

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 1 / 133 Northeastern Illinois Overview University

Low Mass Stars White Dwarfs Novae and WD Supernovae Supernovae Neutron Stars Relativity Black Holes Gamma Ray Bursts Review

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 2 / 133 Northeastern Illinois Stellar Remnants University

The endpoint of isolated stars: Star Mass Remnant

M . 0.08M⊙ Brown Dwarf

0.08M⊙ . M . 8M⊙ Planetary Nebula ⇒ WD

8M⊙ . M . 20M⊙ Supernovae ⇒ NS

20M⊙ . M Hypernovae ⇒ BH http://arxiv.org/abs/astro-ph/0410690 White Dwarf Cosmochronology http://arxiv.org/pdf/astro-ph/0212469v1.pdf

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 3 / 133 Northeastern Illinois University

Stellar Remnants

Low Mass Stars HR Diagram Fig 12.12: Evolution of Low Mass Star Butterﬂy Nebula

White Dwarfs Novae and WD Supernovae Low Mass Stars Supernovae

Neutron Stars

Relativity

Black Holes Gamma Ray Bursts

Review

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 4 / 133 Northeastern Illinois Hertzsprung-Russell (H-R) Diagram University Temperature (K) 40,000 10,000 7,000 6,000 5,000 4,000 3,000 2,500 106 −10 O B A b F G K M b

b b

b b ( Magnitude Absolute b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b 4 b b b b b b b b b b b b b b b b b b b b b b b b b b b ) b b b b b −5 b b b b b b 10 b b b b b b b b b b b b b b b b b b b b b ⊙ b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb bb b b bb b b b b b b L/L b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b bb b b b 2 b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b bb b b b b b b b bb b b b b b b b b b b bb b b b b b b bb b b b b bb b b b b b b bb b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b bb b b b b b bb b b b b b b b b b b b b b b b bb bb b b b bb b b bb b b b b b b b b b b b b b b b b b bb b b bb b b b b b b b b bb b b b b b b b b b b b bb b b b b b b bb b 0 b b b b b b b b b b b b b b b bb b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b 10 b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b bb b b b bb b b bb b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b bbb b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b bb bb b b b b b b bb b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b bb b b b b b bbb b b b b b b b b b b b b b b b b b b b b b b b bb b b bb bbb b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b bb b b b b b b b b b b b b b b b b b b b b b b bb b b bb b b bbbb b b bb b b b b bb b b b b b b b b b b b b b b b b b b b b b bb b b bb b b b b b b b b b b b b b b b b b b b b b b bbb b b b b b b bb b b b b bb b b b b b b b b b b b b bb b bb b b b b b b bb bbb b b b bbb b bb b bb b b b b b b b b b b b b b b b b b b b b b bb bb b b b b b b b b b b b b b b b b bb bb b bbb b b b b b b b bb b bb bb b b b b b b b b b bb bb b b b b b bb bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b bb b b b b b b b b bb b b b b b b b b bb b b b b b b b b b b b b b bb b b b b b b b b bb b bb b b b b b b b b b bb b b b b b b b b b b b b b b bb b b b b bb b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b bbbb b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b bb bb b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b bb b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b bbb b b b b b b bb b b bbb b b b b bb b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b bb b b bbb b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b bb b b b b b b b bb bb b b b b b b b b b b b bb b b b b b b b b b b b 0 b b bb b b b b b b b b b b b bb b b b b b b b b b b bb b b b b b b b bb b bb b b b b b b b bb b b b b b b b b b b b bb b b b b b b b b b b b bb b b b b b b b b b b 5 b b b b b b b b 10 b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b

b M b b b b b b b b b

Luminosity ( b b b b b b b b b b b b bb b b b b b b b b b b b b b 2 b b b V − b b b b b b b b b b b b b b b b bb b b bb b b b b bb b b b b b b b 10 b b b bb b b b b b b b b ) 10 b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b bb b b bb b b b b b b b b b bb b b b b bbb bb bb b b b b b b b bb b b b b b b b b bb b b b b b b b b b b bb b b b b b b b b b b b b −4 b b b b b b b b b b 15 10 b b −0.5 0 0.5 1.0 1.5b 2.0 Color Index (B − V )

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 5 / 133

NGC 6302 (Butterﬂy Nebula) Northeastern Illinois University

Stellar Remnants

Low Mass Stars

White Dwarfs White Dwarfs (WD) Q: White Dwarf White Dwarfs in M4 Q: WD Pressure Canis Major (IAU) White Dwarfs Optical: Sirius B & Sirius A Chandra: Sirius B & Sirius A Sirius A & Sirius B Canis Minor (IAU) Procyon AB Lucy in the Sky with Diamonds Size of a White Dwarf Q: WD Size Q: Teaspoon of WD Q: WD Mass White Dwarf Limit Chandrasekhar Limit c 2012-2019G. Anderson Universe: Past, Present & Future – slide 8 / 133 Q: WD Mass Northeastern Illinois White Dwarfs (WD) University Exposed core of a dead star which has shed its outer layers in a planetary nebula.

• Stars with M . 8M⊙, 97% of stars, end their lives as white dwarfs.

• Upper (Chandrasekhar) mass limit : M < 1.4M⊙

• Typical mass: M ≈ M⊙

• Typical size: R ≈ R⊕ • Supported against gravity by electron degeneracy pressure. • Isolated WD cool oﬀ over time → black dwarf.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 9 / 133 Northeastern Illinois Q: White Dwarf University A white dwarf is A) the exposed core of a dead star, supported by electron degeneracy pressure. B) the exposed core of a dead star, supported by neutron degeneracy pressure. C) a hot but very small main sequence star with a mass of less than 1.4 solar masses. D) a cool and very small main sequence star with a mass of less than 1.4 of a solar masses. E) the singularity at the center of a black hole.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 10 / 133 Northeastern Illinois Q: White Dwarf University A white dwarf is A) the exposed core of a dead star, supported by electron degeneracy pressure. B) the exposed core of a dead star, supported by neutron degeneracy pressure. C) a hot but very small main sequence star with a mass of less than 1.4 solar masses. D) a cool and very small main sequence star with a mass of less than 1.4 of a solar masses. E) the singularity at the center of a black hole.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 10 / 133

Northeastern Illinois Q: WD Pressure University

What kind of pressure supports a white dwarf against the pull of gravity? A) thermal pressure B) radiation pressure C) electron degeneracy pressure D) neutron degeneracy pressure

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 12 / 133 Northeastern Illinois Q: WD Pressure University

What kind of pressure supports a white dwarf against the pull of gravity? A) thermal pressure B) radiation pressure C) electron degeneracy pressure D) neutron degeneracy pressure

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 12 / 133

Sirius A and Sirius B (Visible) Sirius B and Sirius A (X-ray) Northeastern Illinois Sirius A & Sirius B University

1844 with careful measurements, Friedrich Wilhelm Bessel discovers Sirius is a binary star.

Distance (parallax angle = 0.38′′)

d =2.6pc=8.6ly

Sirius A and B α CMa A α CMa B T 9910 K 27000 K a = 20 AU M 2.02M⊙ 0.98M⊙ p = 50years L 23.5L⊙ 0.03L⊙ ǫ =0.6

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 16 / 133

Procyon AB MA =1.5M⊙, MB =0.6M⊙ Northeastern Illinois Lucy in the Sky with Diamonds University

• A WD may crystallize when cool enough, resulting in a solid of carbon and oxygen. • Observing WD pulsations gives information about its struc- ture. • Crystaline WD veriﬁed in 2004 with discovery of WD BPM-37093.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 19 / 133 Northeastern Illinois Size of a White Dwarf University

Higher-mass white dwarfs are smaller

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 20 / 133 Northeastern Illinois Q: White Dwarf Size University

Which of the following is closest in size (radius) to a white dwarf? A) the Earth B) a small city C) a football stadium D) a basketball E) the Sun

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 21 / 133 Northeastern Illinois Q: White Dwarf Size University

Which of the following is closest in size (radius) to a white dwarf? A) the Earth B) a small city C) a football stadium D) a basketball E) the Sun

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 21 / 133 Northeastern Illinois Q: Teaspoon of WD University

A teaspoonful of white dwarf material on Earth would weigh A) a few grams. B) a few pounds. C) a few tons. D) about the same as Mt. Everest. E) about the same as the Earth.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 22 / 133 Northeastern Illinois Q: Teaspoon of WD University

A teaspoonful of white dwarf material on Earth would weigh A) a few grams. B) a few pounds. C) a few tons. D) about the same as Mt. Everest. E) about the same as the Earth.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 22 / 133 Northeastern Illinois Q: White Dwarf Mass University

Which of the following is closest in mass to a white dwarf? A) the Moon B) the Earth C) Jupiter D) the Sun

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 23 / 133 Northeastern Illinois Q: White Dwarf Mass University

Which of the following is closest in mass to a white dwarf? A) the Moon B) the Earth C) Jupiter D) the Sun

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 23 / 133 Northeastern Illinois White Dwarf Limit University Chandrasekhar Limit: • Quantum mechanics: electron momentum must increases as electrons are squeezed into a smaller space. • As a white dwarf’s mass ap- proaches 1.4M⊙, the velocity of the most energetic electrons ap- proaches the speed of light, and no more mass can be supported.

• A white more massive than 1.4M⊙ could not support itself against gravitational collapse.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 24 / 133

Northeastern Illinois Q: WD Mass Limit University

Why is there an upper limit to the mass of a white dwarf?

A) Stars with masses less than 1.4 solar masses don’t form white dwarfs.

B) The more massive the white dwarf, the greater the degeneracy pressure and the faster the speeds of its electrons. Near 1.4 solar masses, the speeds of the electrons approach the speed of light, and no more mass can be supported.

C) The more massive the white dwarf, the higher its temperature and hence the greater its degeneracy pressure. Near 1.4 solar masses, the temperature becomes so high that all matter eﬀectively melts into subatomic particles.

D) The upper limit to the masses of white dwarfs was determined through observations of white dwarfs in binary systems, but no one knows why the limit exists. c 2012-2019G. Anderson Universe: Past, Present & Future – slide 26 / 133 Northeastern Illinois Q: WD Mass Limit University

Why is there an upper limit to the mass of a white dwarf?

A) Stars with masses less than 1.4 solar masses don’t form white dwarfs.

D) The upper limit to the masses of white dwarfs was determined through observations of white dwarfs in binary systems, but no c 2012-2019G.one Anderson knows why the limit exists. Universe: Past, Present & Future – slide 26 / 133 Northeastern Illinois Q: White Dwarf Mass Limit University

What is the upper limit to the mass of a white dwarf? A) 1.4 solar masses B) 2 solar masses C) 3.2 solar masses D) 8 solar masses E) There is no upper limit.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 27 / 133 Northeastern Illinois Q: White Dwarf Mass Limit University

What is the upper limit to the mass of a white dwarf? A) 1.4 solar masses B) 2 solar masses C) 3.2 solar masses D) 8 solar masses E) There is no upper limit.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 27 / 133 Northeastern Illinois Q: WD Fate University

What is the ultimate fate of an isolated white dwarf?

A) It will cool down and become a cold black dwarf.

B) As gravity overwhelms the electron degeneracy pressure, it will explode as a nova.

C) As gravity overwhelms the electron degeneracy pressure, it will explode as a supernova.

D) As gravity overwhelms the electron degeneracy pressure, it will become a neutron star.

E) The electron degeneracy pressure slowly overwhelms gravity and the white dwarf evaporates.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 28 / 133 Northeastern Illinois Q: WD Fate University

What is the ultimate fate of an isolated white dwarf?

A) It will cool down and become a cold black dwarf.

B) As gravity overwhelms the electron degeneracy pressure, it will explode as a nova.

C) As gravity overwhelms the electron degeneracy pressure, it will explode as a supernova.

D) As gravity overwhelms the electron degeneracy pressure, it will become a neutron star.

E) The electron degeneracy pressure slowly overwhelms gravity and the white dwarf evaporates.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 28 / 133 Northeastern Illinois University

Stellar Remnants

Low Mass Stars

White Dwarfs Novae and WD Supernovae Accretion Disk around WD Accretion Disk around WD 2 Novae and WD Accretion Disks Nova (pl. Novae) Nova T Pyxidis T or F: Novae Supernovae Type Ia SN SN1994D SN 1006 Supernova Remnant Q: 1.4M⊙ Limit White Dwarfs (WD) Close Binary Systems

Supernovae

Neutron Stars

Relativity

Black Holes c 2012-2019G. Anderson Universe: Past, Present & Future – slide 29 / 133 Gamma Ray Bursts NASA Image: Accretion disc around white dwarf

Northeastern Illinois Accretion Disks University

• Mass falling toward a white dwarf from its close binary companion has angular momentum. • The matter therefore orbits the white dwarf in an accretion disk. • Friction between orbiting rings of matter in the disk transfers angular momentum and causes the disk to heat up and glow.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 32 / 133 Northeastern Illinois Nova (pl. Novae) University

• WD accretes matter from close binary companion. • The temperature of accreted matter eventually becomes hot enough for hydrogen fusion. • Fusion begins suddenly and explo- sively, causing a nova. • The nova star system temporarily appears much brighter. • The nuclear explosion drives accreted matter into space.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 33 / 133 Nova remnant: T Pyxidis Northeastern Illinois T or F: Novae University

Are the following statements true or false?

A) A star system that undergoes a nova may have another nova sometime in the future.

B) A nova involves fusion taking place on the surface of a white dwarf.

C) Our Sun will probably undergo at least one nova when it becomes a white dwarf about 5 billion years from now.

D) When a star system undergoes a nova, it brightens considerably, but not as much as a star system undergoing a supernova.

E) The word nova means “new star” and originally referred to stars that suddenly appeared in the sky, then disappeared again after a few weeks or months.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 35 / 133 Northeastern Illinois T or F: Novae University

Are the following statements true or false?

T A star system that undergoes a nova may have another nova sometime in the future.

T A nova involves fusion taking place on the surface of a white dwarf.

F Our Sun will probably undergo at least one nova when it becomes a white dwarf about 5 billion years from now.

T When a star system undergoes a nova, it brightens considerably, but not as much as a star system undergoing a supernova.

T The word nova means “new star” and originally referred to stars that suddenly appeared in the sky, then disappeared again after a few weeks or months.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 35 / 133 Northeastern Illinois Type Ia Supernovae University

Type Ia supernova: violent explosion of a white dwarf star.

9 LSN ≈ 4 × 10 L⊙

White dwarf: a “burned out” star which is supported by electron degeneracy pressure. White dwarfs are very dense. Mass ≈ Sun and volume ≈ Earth. ⇒ 200,000 times as dense as the earth.

White dwarfs become unstable when their mass reaches the Chandrasekhar limit for a white dwarf M < 1.4M⊙. Collapse triggers carbon fusion.

12C+ 12C −→ 20Ne + 4He + energy

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 36 / 133 SN 1994D in NGC 4526 SN 1006: Ia Supernova Remnant Northeastern Illinois Q: 1.4M⊙ Limit University

Suppose a white dwarf is accreting mass from a binary companion. What happens if its mass reaches the 1.4 solar mass limit?

A) The white dwarf undergoes a collapse and expels the excess mass in a nova eruption.

B) The white dwarf (which is made mostly of carbon) suddenly detonates carbon fusion and this creates a white dwarf supernova explosion.

C) The white dwarf immediately collapses into a black hole, disappearing from view.

D) A white dwarf can never gain enough mass to reach the limit because a strong stellar wind prevents the accreting material from reaching it in the ﬁrst place.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 39 / 133 Northeastern Illinois Q: 1.4M⊙ Limit University

Suppose a white dwarf is accreting mass from a binary companion. What happens if its mass reaches the 1.4 solar mass limit?

A) The white dwarf undergoes a collapse and expels the excess mass in a nova eruption.

B) The white dwarf (which is made mostly of carbon) suddenly detonates carbon fusion and this creates a white dwarf supernova explosion.

C) The white dwarf immediately collapses into a black hole, disappearing from view.

D) A white dwarf can never gain enough mass to reach the limit because a strong stellar wind prevents the accreting material from reaching it in the ﬁrst place.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 39 / 133 Northeastern Illinois White Dwarfs (WD) University Exposed core of a dead star which has shed its outer layers in a planetary nebula.

• Stars with M . 8M⊙, 97% of stars, end their lives as white dwarfs.

• Upper (Chandrasekhar) mass limit : M < 1.4M⊙

• Typical mass: M ≈ M⊙

• Typical size: R ≈ R⊕ • Supported against gravity by electron degeneracy pressure. • Isolated WD cool oﬀ over time → black dwarf.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 40 / 133 Northeastern Illinois Close Binary Systems University

For a WD in a close binary system: • Matter from its close binary companion can fall onto the white dwarf through an accretion disk. • Accretion of matter can lead to novae and white dwarf supernovae.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 41 / 133 Northeastern Illinois University

Stellar Remnants

Low Mass Stars

White Dwarfs Novae and WD Supernovae

Supernovae Novae and Supernovae Multiple Shell Fusion Supernovae Massive Star Supernovae Massive Star SN vs WD SN SN Light Curves Stellar Remnants Taurus (IAU) Crab Nebula

Neutron Stars

Relativity

Black Holes Gamma Ray Bursts

Review

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 42 / 133 Northeastern Illinois Novae and Supernovae University

Novae: Nuclear explosion on the surface of a white dwarf when accumulated hydrogen is heated to the point that H to He fusion begins. White dwarf left 5 intact. (L ≈ 10 L⊙). Supernovae: A stellar explosion that is much more 10 luminous than a nova (L ≈ 10 L⊙). Can outshine an entire galaxy. White dwarf supernova (Type Ia): Carbon fusion suddenly begins as white dwarf in close binary system reaches white dwarf limit, causing a total explosion. No WD left behind. Massive star supernovae (Type II, Ib, Ic): Iron core of massive star reaches white dwarf limit and collapses into a neutron star, causing an explosion.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 43 / 133 Northeastern Illinois Multiple Shell Fusion University H fusing shell He fusing shell C fusing shell Oxygen

Iron core Silicon Magnesium Neon

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 44 / 133 Northeastern Illinois Massive Star Supernovae University

Fe builds up in the core until degeneracy pressure can no longer resist gravity. Core collapses creating a supernova explosion:

− e + p −→ n + νe

Neutrons collapse forming a neutron star. ν,γ

ejecta

Fe ν,γ ν,γ

ν,γ

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 45 / 133 Northeastern Illinois Massive Star SN vs WD SN University

• Light curves diﬀer

• Spectra diﬀer - Type I SN don’t have H absorption lines

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 46 / 133

Northeastern Illinois Stellar Remnants University

The endpoint of isolated stars: Star Mass Remnant

M . 0.08M⊙ Brown Dwarf

0.08M⊙ . M . 8M⊙ Planetary Nebula ⇒ WD

8M⊙ . M . 20M⊙ Supernovae ⇒ NS

20M⊙ . M Hypernovae ⇒ BH http://arxiv.org/abs/astro-ph/0410690 White Dwarf Cosmochronology http://arxiv.org/pdf/astro-ph/0212469v1.pdf

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 48 / 133

M1: Crab Nebula in Taurus, 1054 type II SN Remnant Northeastern Illinois University

Stellar Remnants

Low Mass Stars

White Dwarfs Novae and WD Supernovae

Supernovae

Neutron Stars Q: Massive-Star Supernova Neutron Stars & Neutron Stars Pulsars Neutron Stars (NS) Neutron Star Neutron Star (R = 2Rs) Q: A piece of Neutron Star Q: Neutron Star Radius Discovery of Pulsars (Neutron Stars) Jocelyn Bell discovers Pulsars Pulsar Pulsars Pulsar Model Crab Nebula Crab c 2012-2019G. Nebula II Anderson Universe: Past, Present & Future – slide 51 / 133 Crab Nebula III Northeastern Illinois Q: Massive-Star Supernova University

After a massive-star supernova, what is left behind? A) Always a white dwarf B) Always a neutron star C) Always a black hole D) Either a white dwarf or a neutron star E) Either a neutron star or a black hole

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 52 / 133 Northeastern Illinois Q: Massive-Star Supernova University

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 52 / 133 Northeastern Illinois Neutron Stars & Pulsars University

neutron star An extremely dense ball of neutrons, supported by neutron degeneracy pressure, from the collapsed core of a massive star during a supernova explosion. pulsar (pulsating star) is a rapidly rotating neutron star that regularly emits pulses of radiation, usually radio waves, is known as a pulsar. xray-burster X-rays bursts from fusion ignition in matter being accreted on to a neutron star in a binary system.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 53 / 133 Northeastern Illinois Neutron Stars (NS) University

• Proposed by Walter Baade and Fritz Zwicky in 1934. • Jocelyn Bell and Antony Hewish discover radio pulsars in 1967. • Supported against gravity by neutron degeneracy pressure. • The Tolman-Oppenheimer-Volkoﬀ (TOV) upper mass limit for neutron stars: M . 3.2M⊙

• Mass range: 1.4M⊙ . M . 3.2M⊙ • Typical size: R ≈ 12km (the size of a small city)

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 54 / 133 Supernova remnant Cas A contains a neutron superﬂuid Northeastern Illinois Neutron Star (R =2Rs) University

Gravitational light deﬂection from a neutron star. c 2012-2019G. Anderson Universe: Past, Present & Future – slide 56 / 133 Northeastern Illinois Q: A piece of Neutron Star University

A paperclip with the density of a neutron star would weigh (on the Earth) A) about the same as a regular paperclip. B) a few tons. C) more than Mt. Everest. D) more than the Moon. E) more than the Earth.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 57 / 133 Northeastern Illinois Q: A piece of Neutron Star University

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 57 / 133 Northeastern Illinois Q: Neutron Star Radius University

Which of the following is closest in size (radius) to a neutron star? A) the Earth B) a city C) a football stadium D) the Sun

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 58 / 133 Northeastern Illinois Q: Neutron Star Radius University

Which of the following is closest in size (radius) to a neutron star? A) the Earth B) a city C) a football stadium D) the Sun

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 58 / 133 Northeastern Illinois Discovery of Pulsars (Neutron Stars) University

• Using a radio telescope in 1967, Jocelyn Bell noticed very regular pulses of radio emission coming from a single part of the sky. • The pulses were coming from a spinning neutron star -a pulsar.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 59 / 133 Northeastern Illinois Discovery of Pulsars (Neutron Stars) University

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 59 / 133 Northeastern Illinois Jocelyn Bell discovers Pulsars University

“In 1967, a twenty-four year old post graduate student made one of the greatest astronomical discov- eries in living memory, ...When analysing three miles of radio telescope data by hand in 1967 at the University of Cambridge, Jocelyn Bell identiﬁed a regular pulse of ra- diowaves. Seemingly too regular to be anything but man-made, months of further research led Jocelyn to discover the origin of the signal was over 200 light-years away.”

Jocelyn Bell (1968) – Gia Milinovich Mullard Radio Observatory University of Cambridge.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 60 / 133 Northeastern Illinois Pulsar University Pulsar = Pulsating star. Highly magnetized, neutron-star beaming radiation along a magnetic axis that is not aligned with the rotation axis..

Optical & X-ray image of crab nebula

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 61 / 133

Gamma Ray Pulsar Model Pulsar at center of Crab Nebula pulses 30 times per second Crab Nebula (X-ray +(Optical) Crab Nebula Vela Pulsar (NASA/Chandra): Click for movie Northeastern Illinois Pulsars Must Be Neutron Stars University

• Spin Rate of Fast Pulsars ∼ 1000 cycles per second

• Circumference of Neutron Star = 2π(radius) ≈ 60 km

• Surface Rotation Velocity ∼ 60, 000 km/s ∼ 20% speed of light ∼ escape velocity from NS

Anything else would be torn to pieces!

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 68 / 133 Northeastern Illinois Q: Pulsar Identity University

What is a pulsar? A) a star that alternately expands and contracts in size B) a rapidly rotating neutron star C) a neutron star or black hole that happens to be in a binary system D) a binary system that happens to be aligned so that one star periodically eclipses the other E) a star that is burning iron in its core

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 69 / 133 Northeastern Illinois Q: Pulsar Identity University

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 69 / 133 Northeastern Illinois Q: Pulsars are NS University

How do we know that pulsars must be neutron stars?

A) We have observed massive-star supernovae produce pulsars.

B) Telescopic images of pulsars and neutron stars look exactly the same.

C) No massive object, other than a neutron star, could spin as fast as we observe pulsars to spin and remain intact.

D) Pulsars have the same upper mass limit as neutron stars do.

E) This is only a theory that has not yet been conﬁrmed by observations.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 70 / 133 Northeastern Illinois Q: Pulsars are NS University

How do we know that pulsars must be neutron stars?

A) We have observed massive-star supernovae produce pulsars.

B) Telescopic images of pulsars and neutron stars look exactly the same.

C) No massive object, other than a neutron star, could spin as fast as we observe pulsars to spin and remain intact.

D) Pulsars have the same upper mass limit as neutron stars do.

E) This is only a theory that has not yet been conﬁrmed by observations.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 70 / 133 Northeastern Illinois Q: Pulsar University

What causes the radio pulses of a pulsar?

A) The vibration of the neutron star.

B) As the neutron star spins, beams of radio radiation sweep through space. If one of the beams crosses the Earth, we observe a pulse.

C) The neutron star undergoes periodic explosions of nuclear fusion that generate radio pulses.

D) The neutron star’s orbiting companion periodically eclipses the radio waves that the neutron star emits.

E) A black hole near the neutron star absorbs energy and re-emits it as radio waves.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 71 / 133 Northeastern Illinois Q: Pulsar University

What causes the radio pulses of a pulsar?

A) The vibration of the neutron star.

B) As the neutron star spins, beams of radio radiation sweep through space. If one of the beams crosses the Earth, we observe a pulse.

C) The neutron star undergoes periodic explosions of nuclear fusion that generate radio pulses.

D) The neutron star’s orbiting companion periodically eclipses the radio waves that the neutron star emits.

E) A black hole near the neutron star absorbs energy and re-emits it as radio waves.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 71 / 133 Accretion disk around Neutron Star: Image Credit: NASA Northeastern Illinois X-ray Bursts University

Accreting matter adds angular momentum to a neutron star, in- creasing its spin. Episodes of fusion on the surface lead to X-ray bursts.

X-ray bursters are to neutron stars what novae are white dwarfs.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 73 / 133 Northeastern Illinois X-ray Bursts University

Matter accreting onto a neutron star can eventually become hot enough for helium to fuse.

The sudden onset of fusion produces a burst of X rays.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 74 / 133 Northeastern Illinois University

Stellar Remnants

Low Mass Stars

White Dwarfs Novae and WD Supernovae

Supernovae

Neutron Stars

Relativity Postulates Relativity Mass Equivalence Principle of Equivalence (strong form) General Relativity Postulates of Euclidean Geometry Alternative Geometries Pos. Curvature Neg. Curvature Curvature & Energy Density Gravity from Curvature Eddington Gravitational c 2012-2019G. Anderson Universe: Past, Present & Future – slide 75 / 133 Lensing Northeastern Illinois Postulates of Special Relativity University

Special Relativity (1905)

The Relativity Postulate: The basic laws of physics are the same in all inertial reference frames.

Speed of Light Postulate: The speed of light in vacuum has the same value c in all inertial reference frames. Albert Einstein (1879-1955) at age 26.

From the Emilio Segr´eVisual Archives

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 76 / 133 Northeastern Illinois Gravitational and Inertial Mass University

Inertial Mass F = mia Gravitational Mass M m F = −G g g r2 Equivalence Principle (weak form)

mi = mg

If gravitational and intertial mass are equivalent there is no distinction between an accerated frame and a uniform gravitational ﬁeld.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 77 / 133 Northeastern Illinois Principle of Equivalence (strong form) University

A homogeneous gravitational ﬁeld is equivalent to a uniformly accelerated reference frame.

⋆ ⋆

b b b b a g g g

⋆ ⋆

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 78 / 133 Northeastern Illinois Principle of Equivalence (strong form) University

A homogeneous gravitational ﬁeld is equivalent to a uniformly accelerated reference frame.

⋆ ⋆

b b b b

g ⋆ ⋆

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 78 / 133 Northeastern Illinois Light in an Accelerated Frame University

A homogeneous gravitational ﬁeld is equivalent to a uniformly accelerated reference frame.

⋆ v =0 ⋆ ⋆ a =0 ⋆

⋆

⋆ ⋆

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 79 / 133 Northeastern Illinois Light in an Accelerated Frame University

A homogeneous gravitational ﬁeld is equivalent to a uniformly accelerated reference frame.

⋆ v =06 ⋆ ⋆ a =0 ⋆

⋆

⋆ ⋆

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 79 / 133 Northeastern Illinois Light in an Accelerated Frame University

A homogeneous gravitational ﬁeld is equivalent to a uniformly accelerated reference frame.

⋆ ⋆ ⋆ a =06 ⋆

⋆

⋆ ⋆

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 79 / 133 Northeastern Illinois Light and Uniform Gravity University

A homogeneous gravitational ﬁeld is equivalent to a uniformly accelerated reference frame.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 80 / 133 Northeastern Illinois General Relativity University

Predictions and consequences of General Relativity: • Curvature of space-time • Gravitational lensing • Precession of perihelion of Mercury • Gravitational Red Shift • Black Holes • Gravity Waves • Expansion of the Universe

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 81 / 133 Northeastern Illinois Postulates of Euclidean Geometry University

1. It is possible to draw a straight line from any point to any point. 2. It is possible to extend a ﬁnite straight line continuously in a straight line 3. It is possible to describe a circle with any center and radius. 4. All right angles are equal to one another. 5. Given, in a plane, a line L and a point P not on L, there is one and only one line parallel to L.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 82 / 133 Northeastern Illinois Alternative Geometries University Parallel Lines: Lines in a plane that do not intersect. Euclid’s 5th Postulate & Alternatives: 5a. Given, in a plane, a line L and a point P not on L, then through P there exists one and only one line parallel to L. 5b. Given, in a plane, a line L and a point P not on L, then through P there exists no line parallel to L. 5c. Given, in a plane, a line L and a point P not on L, then through P there exists at least two lines parallel to L.

Pb Pb Pb

a. Euclidean b. Elliptic c. Hyperbolic

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 83 / 133 Northeastern Illinois Positive Curvature University

Non Euclidean Geometry: • Interior Angles =6 π P γ

A α β Positive curvature A α + β + γ = π + R2

C < 2πr (2D) A< 4πr2 (3D)

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 84 / 133 Northeastern Illinois Negative Curvature University z

γ x A α β

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 85 / 133 Northeastern Illinois Curvature & Energy Density University

Einstein’s Equation

curvature energy  of  = G  density of  space-time space-time     Analogy

Small Mass

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 86 / 133 Northeastern Illinois Curvature & Energy Density University

Einstein’s Equation

curvature energy  of  = G  density of  space-time space-time     Analogy

Bigger Mass

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 86 / 133 Northeastern Illinois Curvature & Energy Density University

Einstein’s Equation

curvature energy  of  = G  density of  space-time space-time     Analogy

Even Bigger Mass

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 86 / 133 Northeastern Illinois Gravity from Curvature University

Gravity is a manifestation of curvature

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 87 / 133 Northeastern Illinois Gravity from Curvature University

Gravity is a manifestation of curvature

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 87 / 133 Northeastern Illinois “Bending” of Light University

Predicted by Einstein in 1915. Conﬁrmed by Arthur Eddington in 1919 by measuring deﬂection of starlight during a solar eclipse. ⋆ ⋆ α

GM⊙ α =4 2 ≈ 1.75 arcseconds c R⊙ Observation:

α =1.61 ± 0.30 arcseconds R⊙ = distance of closest approach

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 88 / 133 Northeastern Illinois “Bending” of Light II University

Sun

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 89 / 133 Hubble space telescope: Gravitational lensing in Abell 2218. STScI Photo: The Einsten Cross, galaxy lenses a background quasar. Northeastern Illinois Precession of Mercury’s Perihelion University

Precession of perihelion of Mercury = 43 arc seconds per century.

The closest point to the Sun in a planet’s orbit is called perihelion. The furthest point is called aphelion.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 92 / 133 Northeastern Illinois Gravitational Redshift University

λo Redshift:

λobserved − λemitted z = 2 λemitted h g =9.8m/s Near Earth’s Surface (h ≪ R):

λo − λe gh z = ≈ 2 λe λe c

Conﬁrmed by Pound & Rebka Phys. Rev. Lett. 4, 337 (1960). High above (h ≫ R):

λo − λe GM z = ≈ 2 λe c R

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 93 / 133 Northeastern Illinois Q: GR Redshift University

Which of the following correctly describes how light will be aﬀected as it tries to escape from a massive object?

A) Light doesn’t have mass; therefore, it is not aﬀected by gravity.

B) Light escaping from a compact massive object, such as a neutron star, will be red-shifted.

C) Light escaping from a compact massive object, such as a neutron star, will be blue-shifted.

D) Visible light escaping from a compact massive object, such as a neutron star, will be red-shifted, but higher frequencies, such as X-rays and gamma rays, will not be aﬀected.

E) Less energetic light will not be able to escape from a compact massive object, such as a neutron star, but more energetic light will be able to. c 2012-2019G. Anderson Universe: Past, Present & Future – slide 94 / 133 Northeastern Illinois Q: GR Redshift University

Which of the following correctly describes how light will be aﬀected as it tries to escape from a massive object?

A) Light doesn’t have mass; therefore, it is not aﬀected by gravity.

B) Light escaping from a compact massive object, such as a neutron star, will be red-shifted.

C) Light escaping from a compact massive object, such as a neutron star, will be blue-shifted.

D) Visible light escaping from a compact massive object, such as a neutron star, will be red-shifted, but higher frequencies, such as X-rays and gamma rays, will not be aﬀected.

Gravitational Waves • Ripples in the fabric of space-time • Carry away energy, angular momentum

1993 Nobel Prize: 1974 Hulse-Taylor pulsar (PSR B1913+16), a pair of neutron stars losing energy through gravitational waves.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 95 / 133

Northeastern Illinois LIGO & Virgo University

• Laser Interferometer Gravitational-Wave Observatory (LIGO) - Hanford, WA and Livingston, LA. • Virgo Interferometer (named for the Virgo Cluster) - Italy • Several direct detection of gravitational waves. • 2017 Nobel Prize: Weiss, Barish, Thorne.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 97 / 133

Northeastern Illinois Ligo Black Holes University

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 99 / 133 Northeastern Illinois University

Stellar Remnants

Low Mass Stars

White Dwarfs Novae and WD Supernovae

Supernovae

Neutron Stars Relativity Black Holes Black Holes BH Image Black Hole Summary Schwarzchild Black Holes Spaghettiﬁcation Extreme Rotating Black Hole Black Hole Thermodynamics Black Hole Masses Stellar Mass BH Accretion Disk surrounding BH Cygnus X-1 Cygnus X-1 Cygnus c 2012-2019G. (IAU) Anderson Universe: Past, Present & Future – slide 100 / 133 Black Hole Simulated Image of a Black Hole Northeastern Illinois Black Hole Summary University

A black hole is a region of spacetime where gravity is so strong that not even light can escape. No Hair Theorem: Black holes are the simplest objects in the universe. You can describe one completely by three externally observable parameters: mass, spin rate, and electric charge.

Size Black holes range in size from M ≈ few M⊙ 9 (R ≈ miles), to M & 10 M⊙ (R ≈ solar system).

Formation A star with M⋆ & 20M⊙ produces a core remnant with M & 3–4M⊙ for which degeneracy pressure is insuﬃcient to prevent gravitational collapse to a black hole.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 102 / 133 Northeastern Illinois Schwarzchild Black Holes University

singularity event horizon

Schwarzschild Radius GM M R =2 2 ≈ 3km c M⊙

Region of spacetime with so much mass, even light cannot escape.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 103 / 133 Northeastern Illinois Spaghettiﬁcation University

Strong tidal forces eventually rip apart objects falling towards the singularity of a BH.

Inside EH for supermassive black holes Outside EH for small black holes.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 104 / 133 Northeastern Illinois Extreme Rotating Black Hole University

J Ergosphere a = M =1

Event Horizon

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 105 / 133 Northeastern Illinois Black Hole Thermodynamics University

Black holes slowly evaporate, via blackbody radiation (Hawking 1974): 3 M τ ≈ 2 × 1067 years M⊙ A 1011 kg black hole evaporates in under 3 billion years.

Entropy (disorder), Temperature, Radius

kAc3 ~c3 2GM S = , T = , R = 2 4G~ 8πGMkB c Hawking Radiation

A ∝ R2 ∝ M 2, T ∝ M −1, L ∝ R2T 4 ∝ M −2, τ ∝ ML−1 ∝ M 3

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 106 / 133 Northeastern Illinois Black Hole Masses University

Stellar-mass black hole (3.2M⊙ . M . 15M⊙) From collapsed core of massive supergiant star with M⋆ & 18M⊙. Example: Cyg X-1. 2 3 Intermediate-mass (10 M⊙ . M . 10 M⊙) Cores of globular clusters and low mass galaxies. Example GCIRS 13E?? which orbits Sgr A*. 5 10 Supermassive black hole (10 M⊙ . M . 10 M⊙) Found in the centers of most (all?) galaxies. Competing theories of formation. Example: Sgr A*.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 107 / 133 J1650-500 J1859+226 GX 339-4 BW Cir GRS1915+105

V404 CYG J1819-254 J1655-40 J1550-564 4U1543-47 H1705-25 GS1124-684 GS2000+25 A0620-00 GRS1009-45 J0422+320 J1118+480

LMC X-3 LMC X-1 CYG X-1 BH with accretion. Illustration: ESA, NASA, and Felix Mirabel Image Credit: ESA/Hubble Northeastern Illinois Cygnus X-1 University

Black hole candidate, Cyg X-1, is the brightest, persistent source of X-rays seen from Earth. Binary system: Blue super-giant and compact object with accretion disk.

Image Credit: ESA/Hubble

M ≈ 14.8M⊙, R ≈ 26km Compact object too small to be anything but a black hole.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 111 / 133

Northeastern Illinois Black Hole Masses University

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 113 / 133 Northeastern Illinois Sagittarius A* University

Sagittarius A-star (Sgr A*): Supermassive black hole in our galaxies center. Discovered 1974 using the NRAO

distance = 26, 000 light − years

From orbital observations

R< 45 AU ∼ aUranus

From orbits of satellite stars:

6 Mbh ≈ 4 × 10 M⊙

For a black hole this massive, the Schwartzchild radius is:

RSch ≈ 0.08AU

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 114 / 133

Northeastern Illinois Q: Black Hole Formation University

How does a black hole form from a massive star?

A) Gravitational collapse to a black hole takes place when the inert core of a massive star or the mass of an accreting neutron star exceeds the TOV limit of 3 − 4 solar masses.

B) Any star that is more massive than 8 solar masses will undergo a supernova explosion and leave behind a black hole remnant.

C) If enough mass is accreted by a white dwarf star that it exceeds the 1.4 solar mass limit, it will undergo a supernova explosion and leave behind a black-hole remnant.

D) A black hole forms when two massive main-sequence stars collide.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 116 / 133 Northeastern Illinois Q: Black Hole Formation University

How does a black hole form from a massive star?

A) Gravitational collapse to a black hole takes place when the inert core of a massive star or the mass of an accreting neutron star exceeds the TOV limit of 3 − 4 solar masses.

B) Any star that is more massive than 8 solar masses will undergo a supernova explosion and leave behind a black hole remnant.

C) If enough mass is accreted by a white dwarf star that it exceeds the 1.4 solar mass limit, it will undergo a supernova explosion and leave behind a black-hole remnant.

D) A black hole forms when two massive main-sequence stars collide.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 116 / 133 Northeastern Illinois TF: Black Holes University True or False: 1. If you watch someone else fall into a black hole, you will never see him or her cross the event horizon. However, he or she will fade from view as the light he or she emits becomes more and more red-shifted. 2. If we watch a clock fall toward a black hole, we will see it tick slower and slower as it falls towards to the black hole. 3. The event horizon of a black hole represents a boundary from which nothing can escape. 4. If the Sun magically disappeared and was replaced by a black hole of the same mass, the Earth would soon be sucked into the black hole. 5. If you fell into a super-massive black hole (so that you could survive the tidal forces), you would experience time to be running normally as you plunged across the event horizon. c 2012-2019G. Anderson Universe: Past, Present & Future – slide 117 / 133 Northeastern Illinois TF: Black Holes University True or False: T: If you watch someone else fall into a black hole, you will never see him or her cross the event horizon. However, he or she will fade from view as the light he or she emits becomes more and more red-shifted. T: If we watch a clock fall toward a black hole, we will see it tick slower and slower as it falls towards to the black hole. T: The event horizon of a black hole represents a boundary from which nothing can escape. F: If the Sun magically disappeared and was replaced by a black hole of the same mass, the Earth would soon be sucked into the black hole. T: If you fell into a super-massive black hole (so that you could survive the tidal forces), you would experience time to be running normally as you plunged across the event horizon. c 2012-2019G. Anderson Universe: Past, Present & Future – slide 117 / 133 Northeastern Illinois University

Stellar Remnants

Low Mass Stars

White Dwarfs Novae and WD Supernovae

Supernovae

Neutron Stars Relativity Gamma Ray Bursts Black Holes Gamma Ray Bursts Gamma Ray Burst Gamma Ray Bursts Burst Duration Burst Duration GRB HST Images GRB Images GRB Images GRB3 CGRO & BATSE BATSE MAP Further Study

Review c 2012-2019G. Anderson Universe: Past, Present & Future – slide 118 / 133 Credit: Nicolle Rager Fuller/NSF Northeastern Illinois Gamma Ray Bursts University

Gamma-ray Busts (GRBs): Extremely energetic explosions producing gamma rays lasting from a fraction of a second to a few minutes. GRBs are the most powerful known explosions of energy in the universe since the Big Bang. The energy in GRBs is believed to be focused in two oppositely directed jets. They occur in distant galaxies.

Discovery: GRBs were ﬁrst detected in 1967 by the Vela satellites, a series of satellites designed to detect covert nuclear weapons tests.

Origin: Massive star supernovae (long duration), merger of binary neutron stars (short duration)

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 120 / 133

Credit: NASA & ESA, GRB (d = 125 million light years) Credit: NASA & ESA, GRB (d = 125 million light years) GRB 990123 Host Galaxy Northeastern Illinois CGRO & BATSE University

Burst And Transient Source Experiment (BATSE): orbital experiment on NASA’s Compton Gamma-Ray Observatory. Nine year mission ended in 2000. Statistical tests conﬁrm that the gamma-ray bursts are isotropically distributed on the sky.

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 127 / 133 2704 BATSE Gamma-Ray Bursts +90

+180 -180

-90

10-7 10-6 10-5 10-4 Fluence, 50-300 keV (ergs cm-2) Northeastern Illinois Further Study University

• Black Hole FAQ (Berkeley) • Neutron Stars • Black Hole Lensing • http://arxiv.org/abs/astro-ph/0612312 • Black Hole Bombs

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 129 / 133 Northeastern Illinois University

Stellar Remnants

Low Mass Stars

White Dwarfs Novae and WD Supernovae

Supernovae

Neutron Stars Relativity Review Black Holes Gamma Ray Bursts

Review Review Review II Review III

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 130 / 133 Northeastern Illinois Review University

• What objects are supported by degeneracy pressure? • How much does a teaspoon of white dwarf material weigh? • What range of main sequence star masses end their lives as white dwarfs? • What is the upper limit on the mass of a white dwarf? • What is the approximate mass and size of a white dwarf? • What is a nova? • When do white dwarfs undergo supernova explosions? • Will our Sun end its life as a white dwarf? If so what will the composition of the white dwarf be?

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 131 / 133 Northeastern Illinois Review II University

• When do massive stars (M & 8M⊙) undergo supernova explosions? • How much does a teaspoon of neutron star material weigh? • What is the approximate mass and size of a neutron star? • What is the upper limit on the mass of a neutron star? • What is a pulsar? Why do they pulse? • What is an x-ray burster?

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 132 / 133 Northeastern Illinois Review III University

• What are the postulates of special relativity? • What are the postulates of general relativity? • What is the singularity of a black hole? • How does the Schwarzchild radius of a black hole depend on its mass? • Do black holes exist?

c 2012-2019G. Anderson Universe: Past, Present & Future – slide 133 / 133