White Dwarfs As Dark Matter Detectors

White Dwarfs as Dark Matter Detectors

Vijay Narayan

with Peter Graham, Ryan Janish, Surjeet Rajendran, and Paul Riggins

(work in progress) Wanted: Dark Matter

m(GeV)

48 10-31 10 Dwarf galaxy Gravitational size effects Non-gravitational interactions? Wanted: Dark Matter

m(GeV)

48 10-31 100 10 Dwarf galaxy Weak Scale Gravitational size effects Non-gravitational interactions?

Challenge of detecting ultra-heavy DM ? m 100 GeV

⇢ 0.4 GeV Event rate scales with DM number density F , ⇢ 3 / m ⇡ cm 1 1022 GeV R 2 Direct Detection exposure limit: F det ⇠ yr m 100 m ✓ ◆✓ ◆ Wanted: Dark Matter

m(GeV) White Dwarfs

48 10-31 100 107 10 Dwarf galaxy Weak Scale Gravitational size effects Non-gravitational interactions?

Challenge of detecting ultra-heavy DM ? m 100 GeV

⇢ 0.4 GeV Event rate scales with DM number density F , ⇢ 3 / m ⇡ cm 1 1022 GeV R 2 Direct Detection exposure limit: F det ⇠ yr m 100 m ✓ ◆✓ ◆ White Dwarfs are uniquely sensitive to such candidates! DM Triggers of Supernovae DM interactions can locally heat WDs, trigger runaway fusion. Ignite type 1a supernovae [Graham et al, 15] DM Triggers of Supernovae DM interactions can locally heat WDs, trigger runaway fusion. Ignite type 1a supernovae [Graham et al, 15]

Extreme detector capability

⌧wd Gyr R 5000 km ⇠ wd ⇠

32 3 2 n 10 cm vesc 10 ion ⇠ ⇠

Spectacular Signature, event visible everywhere DM Triggers of Supernovae DM interactions can locally heat WDs, trigger runaway fusion. Ignite type 1a supernovae [Graham et al, 15]

Extreme detector capability

⌧wd Gyr R 5000 km ⇠ wd ⇠

32 3 2 n 10 cm vesc 10 ion ⇠ ⇠

Spectacular Signature, event visible everywhere This work: constrain wide variety of DM interactions How to Start a Type Ia Supernova

Carbon Fusion Detonation/Deflagration Coulomb Threshold Fusion heats stellar medium faster than it can cool.

Degenerate medium – negligible cooling. Energy Output Thermal diffusion slows with distance:

Trigger Size

Boom How to Start a Type Ia Supernova

Carbon Fusion Detonation/Deflagration Coulomb Threshold Fusion heats stellar medium faster than it can cool.

Degenerate medium – negligible cooling. Energy Output Thermal diffusion slows with distance:

Trigger Size

Runaway fusion How to Start a Type Ia Supernova

Explosion Condition

timescale for (degenerate) electron timescale for carbon- or photon diffusion carbon fusion

A careful calculation (Timmes and Woosley 1992):

Trigger size increases with stellar density How to Start a Type Ia Supernova

Explosion Condition

Careful calculation (Timmes & Woosley, ‘92):

Trigger size larger at lower densities

Energy required to heat a volume to a temperature of

Trigger Energy 1016 GeV Eboom ⇡ DM-induced Type Ia Supernovae

DM can provide local heating by producing high energy SM particles in the WD [Graham, Janish, VN, Rajendran, Riggins, in progress]

Scattering Decay Annihilation

Requires large DM-SM Requires large DM mass cross section

Rate enhanced if DM is captured DM-induced Type Ia Supernovae

DM can provide local heating by producing high energy SM particles in the WD [Graham, Janish, VN, Rajendran, Riggins, in progress]

ScatteringDecay Annihilation

Requires large DMRequires large DM mass-SM x-sec

Rate enhanced if DM is captured DM-Nuclei Elastic Scattering Galactic Center WD

SN Rate

Local WD lifetime DM-induced Type Ia Supernovae

DM can provide local heating by producing high energy SM particles in the WD [Graham, Janish, VN, Rajendran, Riggins, in progress]

Decay Annihilation

Requires large DM mass

Rate enhanced if DM is captured Decay of Captured Dark Matter

Demand for local WDs (with )

Decaying Core

Infall DM Core Collapse in a WD Captured DM can probe and very small cross sections after forming a self-gravitating, collapsing DM core. [Janish, VN, Riggins, in progress]

Three generic outcomes of collapse - black hole - annihilation - stabilization (DM-DM forces, degeneracy)

Hawking radiation heats WD Heating via gravitational acceleration [Graham et al, ‘15] DM Core Collapse in a WD Captured DM can probe and very small cross sections after forming a self-gravitating, collapsing DM core. [Janish, VN, Riggins, in progress]

Three generic outcomes of collapse - black hole - annihilation - stabilization (DM-DM forces, degeneracy)

Hawking radiation heats WD Gravitational acceleration heats WD Core Collapse -> BH Formation Demand for local WDs (Fermion DM)

Hawking

Gravitational Core does not collapse within Gravitational (Fermi) DM Core Collapse in a WD Captured DM can probe and very small cross sections after forming a self-gravitating, collapsing DM core. [Janish, VN, Riggins, in progress]

Three generic outcomes of collapse - black hole - annihilation - stabilization (DM-DM forces, degeneracy)

Core collapses, annihilates at a critical radius .

Usable energy deposit is larger for smaller (!) Annihilation products heat WD. Core Collapse -> Annihilation Burst

Demand for local WDs (with )

2 v ↵ m2 ⇠ Core does Annihilation burst not collapse not explosive. within .

Annihilations at are explosive. Q-ball DM Baryonic Q-ball Scalar condensate stabilized by conserved charge [Coleman ‘85] (B-ball) SUSY theories generically admits B-balls in the form of squarkcondensates. Stable for sufficiently large Q

[Kusenko et al, ‘98] B-ball nuclei interaction Q-ball absorbs baryon number, liberates excess mass energy into pions: Q-ball DM

Local WD lifetime SN Rate Galactic Center WD

BHs

Unstable Q-ball DM

Local WD lifetime SN Rate Galactic Center WD

BHs

Terrestrial Searches [Kusenko et al, ‘98] Unstable White Dwarfs as DM Detectors

Dark matter interactions can locally heat white dwarfs, initiate runaway fusion, and cause (type Ia) supernovae.

High energy SM particles effectively heat a white dwarf and induce SN.

1) Constrain DM-SM scattering, DM decay, DM-DM annihilations

2) Constraints are severe for DM that is captured by the star

3) Core collapse -> BH formation, Annihilation burst. Yields new constraints Alternative type 1a SN progenitor? White Dwarfs as Dark Matter Detectors

Extra Slides How to Start a Type Ia Supernova

Carbon Fusion Detonation/Deflagration Coulomb Threshold Fusion heats stellar medium faster than it can cool.

Degenerate medium – negligible cooling. Energy Output Thermal diffusion slows with distance:

Trigger Size

Boom How to Start a Type Ia Supernova

Carbon Fusion Detonation/Deflagration Coulomb Threshold Fusion heats stellar medium faster than it can cool.

Degenerate medium – negligible cooling. Energy Output Thermal diffusion slows with distance:

Trigger Size

Boom How to Start a Type Ia Supernova

Carbon Fusion Detonation/Deflagration Coulomb Threshold Fusion heats stellar medium faster than it can cool.

Degenerate medium – negligible cooling. Energy Output Thermal diffusion slows with distance:

Trigger Size

Boom How to Start a Type Ia Supernova

Explosion Condition

timescale for (degenerate) electron timescale for carbon- or photon diffusion carbon fusion

A careful calculation (Timmes and Woosley 1992):

Trigger size increases with stellar density How to Start a Type Ia Supernova

Explosion Condition

timescale for (degenerate) electron timescale for carbon- or photon diffusion carbon fusion

A careful calculation (Timmes and Woosley 1992):

Trigger size increases with stellar density How to Start a Type Ia Supernova

Explosion Condition

timescale for (degenerate) electron timescale for carbon- or photon diffusion carbon fusion

A careful calculation (Timmes and Woosley 1992):

Trigger size increases with stellar density How to Start a Type Ia Supernova

Explosion Condition Trigger Energy Energy required to heat a volume to a temperature of How to Start a Type Ia Supernova

Explosion Condition Trigger Energy Energy required to heat a volume to a temperature of DM-induced Type Ia Supernovae

DM can provide local heating by producing high energy SM particles in the WD [Graham, Janish, VN, Rajendran, Riggins, in progress]

Scattering Decay Annihilation

Requires large DM-SM Requires large DM mass cross section

Rate enhanced if DM is captured DM-induced Type Ia Supernovae

DM can provide local heating by producing high energy SM particles in the WD [Graham, Janish, VN, Rajendran, Riggins, in progress]

Scattering Decay Annihilation

Requires large DM-SM x-sec Requires large DM mass

Rate enhanced if DM is captured DM-induced Type Ia Supernovae

DM can provide local heating by producing high energy SM particles in the WD [Graham, Janish, VN, Rajendran, Riggins, in progress]

Scattering Decay Annihilation

Requires large DM-SM x-sec Requires large DM mass

Rate enhanced if DM is captured DM-induced Type Ia Supernovae Captured DM can probe and very small cross sections after forming a self-gravitating, collapsing DM core. [Janish, VN, Riggins, in progress]

Three generic outcomes of collapse - black hole - annihilation - stabilization (DM-DM forces, degeneracy)

Hawking radiation heats WD Heating via gravitational acceleration [Graham et al, ‘15] DM-induced Type Ia Supernovae Captured DM can probe and very small cross sections after forming a self-gravitating, collapsing DM core. [Janish, VN, Riggins, in progress]

Three generic outcomes of collapse - black hole - annihilation - stabilization (DM-DM forces, degeneracy)

Hawking radiation heats WD Gravitational acceleration heats WD DM-induced Type Ia Supernovae Captured DM can probe and very small cross sections after forming a self-gravitating, collapsing DM core. [Janish, VN, Riggins, in progress]

Three generic outcomes of collapse - black hole - annihilation - stabilization (DM-DM forces, degeneracy)

Core collapses, annihilates at a critical radius .

Usable energy deposit is larger for smaller (!) Annihilation products heat WD. Particle Heating of White Dwarfs

Regardless of how SM particles are produced via DM, we must first verify that high energy SM particles will ignite SN.

Ignition may fail if particles stop over a distance , as the SN threshold is parametrically increased:

SN threshold energy

Regardless of how SM particles are produced via DM, we must first verify that high energy SM particles will ignite SN.

Ignition may fail if particles stop over a distance , as the SN threshold is parametrically increased:

SN threshold energy

Regardless of how SM particles are produced via DM, we must first verify that high energy SM particles will ignite SN.

Ignition may fail if particles stop over a distance , as the SN threshold is parametrically increased:

SN threshold energy

Must compute stopping lengths of particles in a WD - Purely a question of SM physics - Stopping lengths are likely short (WDs are dense, and carbon ions provide non-degenerate scattering targets) Particle Stopping in White Dwarfs Incident Particles (DM products) - Electrons, photon, light hadrons, and neutrinos with energy Energy Loss Processes Carbon Ions Electrons fully ionized Coulomb lattice relativistic degenerate gas

Phonon Coulomb Coulomb Free ion Nuclear elastic Compton suppressed by Pauli blocking and Nuclear inelastic (hadronic shower) “standard” electron motion Bremsstrahlung (EM shower) Pair production suppressed by density (LPM) effects Particle Stopping in White Dwarfs Incident Particles (DM products) - Electrons, photon, light hadrons, and neutrinos with energy Energy Loss Processes Carbon Ions Electrons fully ionized Coulomb lattice relativistic degenerate gas

Phonon Coulomb Coulomb Free ion Nuclear elastic Compton Nuclear inelastic (hadronic shower) Bremsstrahlung (EM shower) Pair production Particle Stopping in White Dwarfs Incident Particles (DM products) - Electrons, photon, light hadrons, and neutrinos with energy Energy Loss Processes Carbon Ions Electrons fully ionized Coulomb lattice relativistic degenerate gas

Phonon Coulomb Coulomb Free ion Nuclear elastic Compton suppressed by Pauli blocking and Nuclear inelastic (hadronic shower) electron motion Bremsstrahlung (EM shower) Pair production suppressed by density (LPM) effects Particle Stopping in White Dwarfs Incident Particles (DM products) - Electrons, photon, light hadrons, and neutrinos with energy Energy Loss Processes Carbon Ions Electrons fully ionized Coulomb lattice relativistic degenerate gas

Energy Time

Hadronic Shower Nuclear Elastic Heating

Hadrons thermalize within a trigger size. Particle Stopping in White Dwarfs Incident hadrons

Energy Time

Hadronic Shower Nuclear Elastic Heating

Hadrons thermalize within a trigger size. Particle Stopping in White Dwarfs Incident hadrons

Energy Time

Hadronic Shower Nuclear Elastic Heating

Hadrons thermalize within a trigger size. Particle Stopping in White Dwarfs Incident electrons and photons (high energy)

Energy Time

Electronuclear Shower Photonuclear Shower

High energy , thermalize between and Particle Stopping in White Dwarfs Incident electrons and photons (low energy)

Energy Time

EM Showers Electron-Ion Coulomb Scattering

LPM suppression: decoherence due to multiple ion interactions [Klein, ‘99]

at low energy, gives way to hadronic processes at high energy. Particle Stopping in White Dwarfs

Incident hadrons and photons Incident electrons

Incident neutrinos - this is viable only if a single neutrino is explosive

Proceed assuming DM produces particles that stop within a trigger size. Scattering-induced Supernova

Explosion Condition

1 WD Lifetime ⌧ wd ⇠ transit Scattering-induced Supernova

Explosion Condition

1 WD Lifetime ⌧ wd ⇠ transit

Elastic Scattering off Carbon

! m v2 1 10 MeV Greater than critical temperature ⇠ c esc ⇠ Scattering-induced Supernova

Explosion Condition

1 WD Lifetime ⌧ wd ⇠ transit

Elastic Scattering off Carbon

! m v2 1 10 MeV Greater than critical temperature ⇠ c esc ⇠

Penetrate nondeg envelope Scattering-induced Supernova Galactic Center WD

SN Rate

Local WD lifetime Elastic Capture of Dark Matter Time [Press & Spergel, ‘85] Capture

Stage 1 Orbital decay to stellar surface

Stage 2 Orbital decay from surface to DM thermal radius Elastic Capture of Dark Matter Time [Press & Spergel, ‘85] Capture

Stage 1 Orbital decay to stellar surface

Stage 2 Orbital decay from surface to DM thermal radius Elastic Capture of Dark Matter Time [Press & Spergel, ‘85] Capture

Stage 1 Orbital decay to stellar surface

Stage 2 Orbital decay from surface to DM thermal radius Elastic Capture of Dark Matter Time [Kouvaris & Tinyakov, ‘10] Collection

Collapse Governed by DM cooling and possibly further DM collection. May need to overcome QM pressure.

Black Hole Annihilation Stable Core Elastic Capture of Dark Matter Time [Kouvaris & Tinyakov, ‘10] Collection

Collapse Governed by DM cooling and possibly further DM collection. May need to overcome QM pressure.

Black Hole Annihilation Stable Core Elastic Capture of Dark Matter Time [Kouvaris & Tinyakov, ‘10] Collection

Collapse Governed by DM cooling and possibly further DM collection. May need to overcome QM pressure.

Black Hole Annihilation Stable Core Core Collapse in WD t1 + t2 + tsg < ⌧wd

10-26

10-28

10-30 ��) (�� 10-32 �� )

2 �� 10-34 cm (

A -36 χ 10 σ

10-38

10-40

10-42

10-44

106 108 1010 1012 1014 1016 1018

mχ (GeV) No thermalization No self-gravitation Decay of Captured Dark Matter Constrain three-dimensional space Capture Condition Explosion Condition

Infalling Decay Decaying Core

Constrains all DM that is Constrains decaying DM captured and decays. from a collapse-stable core.

WD Lifetime Decay of Captured Dark Matter Constrain three-dimensional space Capture Condition Explosion Condition

Infalling Decay Decaying Core

Constrains all DM that is Constrains decaying DM captured and decays. from a collapse-stable core.

WD Lifetime Decay of Captured Dark Matter Constrain three-dimensional space Capture Condition Explosion Condition

Infalling Decay Decaying Core

Constrains all DM that is Constrains decaying DM captured and decays. from a collapse-stable core.

WD Lifetime Decay of Captured Dark Matter Constrain three-dimensional space Capture Condition Explosion Condition

Infalling Decay Decaying Core

Constrains all DM that is Constrains decaying DM captured and decays. from a collapse-stable core.

WD Lifetime Decay of Captured Dark Matter

Demand for local WDs (with )

Decaying Core

Infall Decay of Captured Dark Matter

Demand for local WDs (with )

Decaying Core

Infall

Non-capture constraint Dark Matter Black Holes in White Dwarfs

Formation of BHs from DM cores [Kouvaris & Tinyakov, ‘10, ‘12] Dark Matter Black Holes in White Dwarfs

Formation of BHs from DM cores [Kouvaris & Tinyakov, ‘10, ‘12]

classical collapse Dark Matter Black Holes in White Dwarfs

Formation of BHs from DM cores [Kouvaris & Tinyakov, ‘10, ‘12]

overcome Fermi pressure

classical collapse Dark Matter Black Holes in White Dwarfs

Formation of BHs from DM cores [Kouvaris & Tinyakov, ‘10, ‘12]

overcome Fermi pressure

classical collapse

“drip” BHs via BEC (ask me later) BH-induced Supernovae Dynamical Heating Hawking Radiation (gravitational acceleration)

GMBHmc/T > MeV diffusion time

Hawking SN Dynamical SN BH-induced Supernovae Dynamical Heating Hawking Radiation (gravitational acceleration)

GMBHmc/T > MeV diffusion time

Hawking SN Dynamical SN BH-induced Supernovae

Evolution of BHs in White Dwarfs [Kouvaris & Tinyakov, ‘10] Evaporation Accretion

Hawking Bondi accretion Accretion of radiation of stellar medium infalling DM

Hawking SN BH evaporates BH grows Dynamical SN

All BHs that form in a WD will lead to SN. BH-induced Supernovae

Evolution of BHs in White Dwarfs [Kouvaris & Tinyakov, ‘10] Evaporation Accretion

Hawking Bondi accretion Accretion of radiation of stellar medium infalling DM

Hawking SN BH evaporates BH grows Dynamical SN

All BHs that form in a WD will lead to SN. BH-induced Supernovae

Evolution of BHs in White Dwarfs [Kouvaris & Tinyakov, ‘10] Evaporation Accretion

Hawking Bondi accretion Accretion of radiation of stellar medium infalling DM

Hawking SN BH evaporates BH grows Dynamical SN

All BHs that form in a WD will lead to SN. BH-induced Supernovae

Evolution of BHs in White Dwarfs [Kouvaris & Tinyakov, ‘10] Evaporation Accretion

Hawking Bondi accretion Accretion of radiation of stellar medium infalling DM

Hawking SN BH evaporates BH grows Dynamical SN

All BHs that form in a WD will lead to SN. BH-induced Supernovae Demand for local WDs (Fermion DM)

Hawking SN

Dynamical SN Dynamical SN (Fermi) BH does not form within Annihilations and Core Collapse t t ignore annihilations during collection sg ⌧ sat ) Annihilations and Core Collapse t t ignore annihilations during collection sg ⌧ sat ) N 2 Q m sg v min r, 3⌧ ⇠ r3 { T } di↵ ✓ ◆ annihilation rate effective fusion Q spikes as radius decreases per volume volume Annihilations and Core Collapse t t ignore annihilations during collection sg ⌧ sat ) N 2 Q m sg v min r, 3⌧ ⇠ r3 { T } di↵ ✓ ◆ annihilation rate effective fusion Q spikes as radius decreases per volume volume

r3 tcollapse > collapsing core depleting (1) Nsgv ) O

Sets a critical radius at which Q is maximized

Explosion Condition:Q(r) > boom E Scales inversely with annihilation x-sec! Annihilations and Core Collapse

Demand for local WDs (with )

Core does not collapse within . Annihilations and Core Collapse

Demand for local WDs (with )

Core does Core annihilations not collapse are not explosive. within .

Annihilations at are explosive. Annihilations and Core Collapse

Demand for local WDs (with )

↵2 v 2 ⇠ m Core does Core annihilations not collapse are not explosive. within .

Annihilations at are explosive. Q-ball Dark Matter

Q-Ball - Scalar condensate stabilized by a conserved charge - Allowed if is flatter than [Coleman, ‘85] Stability

determined by the lightest particle dynamics of the scalar carrying Q-charge

In the limit of large Q: [Kusenko et al, ‘98]

( - scalar mass)

stable for sufficiently large Q Q-ball Dark Matter

Baryonic Q-ball Supersymmetric theories generically admit B-balls (B-ball) in the form of squarkcondensates. Stability

B-ball – Nucleon Interaction [Kusenko et al, ‘98] Q-ball can absorb baryon number, but only a small fraction of the nucleon’s energy:

Excess energy must be emitted as pions.

Linear Energy Transfer Q-ball Dark Matter

BHs

Unstable Q-balls Q-ball Dark Matter

Local WD lifetime Galactic Center WD

BHs

Dynamical Heating

Unstable Q-balls Q-ball Dark Matter

Local WD lifetime SN Rate Galactic Center WD

BHs

Dynamical Heating

Unstable Q-balls Q-ball Dark Matter

Local WD lifetime SN Rate Galactic Center WD

BHs

Dynamical Heating

Terrestrial Searches [Kusenko et al, ‘98] Unstable Q-balls White Dwarfs as Dark Matter Detectors

Dark matter interactions can locally heat white dwarfs, initiate runaway fusion, and cause (type Ia) supernovae.

High energy SM particles effectively heat a white dwarf and induce SN.

Constrain DM-SM scattering, DM decay, annihilations Constraints are severe for DM that is captured by the star Core collapse -> BH, Annihilating Core provides new constraints

Alternative type 1a SN progenitor? White Dwarfs as Dark Matter Detectors

Extra Slides Particle Heating of White Dwarfs

Explosion Condition

Degenerate Electron Diffusion

Carbon-Carbon - energy released per reaction Fusion

A vastly more careful calculation (Timmes and Woosley 1992): Landau-Pomeranchuk-Midgal Effect

For large target densities and high incident energy, bremsstrahlung radiation is suppressed due to multiple-scattering interactions.

Semi-classical calculations (Klein 1999) including multiple-scattering find a scale

Coulomb log and a suppression factor

For sufficiently large incident energies, LPM will cause radiative EM showers to give way to hadronic showers as the dominant stopping mechanism for electrons and photons. Particle Stopping in White Dwarfs Incident electrons and photons (low energy)

Energy Time Electron-Ion Coulomb Scatters

phonon production

free ion scattering Particle Stopping in White Dwarfs Incident electrons and photons (low energy)

Energy Time Electron-Ion Phonon Production Particle Stopping in White Dwarfs Incident electrons and photons (low energy)

Energy Time Electron-Ion Free Coulomb

Low energy electrons and photons stop below the trigger size. Particle Stopping in White Dwarfs Incident Hadrons Particle Stopping in White Dwarfs Incident Electrons and Photons Constraints on DM-induced SN

Explosion Condition: SM Energy [Graham et al, ‘15] Deposit Heaviest stars give the best constraint: RX J0648.04418 (and 16 others) [Kleinman et al, ‘13]

From DM Interactions Observed

WD Lifetime [DeGennaro et al, ‘07]

SN Rate

Integrate over all WDs that can be ignited, [Van Den Berg, ‘91] and which produce visible SN.

required to yield a visible amount of 56Ni [Sim et al, ‘10] Decay-induced SN Constraints Cosmic Ray [O(1) decay products] Local WD lifetime

(galactic center WD lifetime)

SN Rate CMB (ISW) [Poulin et al, ‘16] CMB (ionization) [Slatyer & Wu, ‘16] Scattering-induced SN Constraints

Scattering Explosion Condition

WD Lifetime

Elastic Scattering Scattering-induced SN Constraints

GC WDs

SN Rate Local WD lifetime Annihilation-induced SN Constraints Cluster Collisions

GC WDs

SN Rate Local WD lifetime Elastic Capture of Dark Matter Capture

Time

Stage 1 - orbital decay to stellar surface

Stage 2 - orbital decay from surface to

Thermal Radius Elastic Capture of Dark Matter Collection

Time

Gravitational Collapse

Annihilation, Black Hole, or Stable Core Elastic Capture of Dark Matter Capture and Collection Timescales

Core Radius Annihilations of Captured DM

Demand for local WDs (with )

Collapse Annihilations Infallannihilations BH-induced Supernovae Constraints Demand for local WDs (Boson DM)

Hawking SN

Dynamical SN BH does not form within Hawking SN (BEC)