Beyond the Standard Model Explanations of GW190521
Jeremy Sakstein (University of Hawai’i) Action Dark Energy, October 2020 [email protected] | jeremysakstein.com
Slide credit: Djuna Croon Phys.Rev. (2020). Le .101102 125, Fromet Abbo Scien fic (LIGO al. R. Collabora on Virgo and Collabora on), GW190521
LIGO/Virgo’s biggest discovery yet: the impossible black holes GW190521
LIGO/Virgo’s biggest discovery yet: the impossible black holes • What is the black hole mass gap? • Why haven’t I heard of it? • Why should I care?
Jeremy Sakstein (University of Hawai’i) Action Dark Energy, October 2020 [email protected] | jeremysakstein.com “The Stellar Binary mergers in LIGO/Virgo O1+O2 Graveyard” Adapted from LIGO-Virgo, Frank Elavsky, Aaron Geller Elavsky, Frank from LIGO-Virgo, Adapted “The Stellar Binary mergers in LIGO/Virgo O1+O2 Graveyard”
Mass Gap?
“Lower Mass Gap” Adapted from LIGO-Virgo, Frank Elavsky, Aaron Geller Elavsky, Frank from LIGO-Virgo, Adapted What populates the stellar graveyard?
• In the LIGO/Virgo mass range: remnants of heavy, low-metallicity population-III stars • Primarily made of hydrogen (H) and helium (He)
• Would have existed for z ≳ 6, M ∼ 20 − 130 M⊙ • Have not been directly observed yet (JWST target)
• Collapsed into black holes in core-collapse supernova explosions. (Or did they?) • We study their evolution from the Zero-Age Helium Branch (ZAHB)
Min = 120M Min = 40M Min = 70M
109 Stellar evolution simulated with MESA 12778*
108 102 103 104 105 106 107
*Paxton et al, arXiv:1710.08424 [astro-ph.SR]
Min = 120M Min = 40M Main nuclear reactions: Min = 70M
109 + 12C(α, γ)16O Stellar evolution simulated with MESA 12778*
108 102 103 104 105 106 107
*Paxton et al, arXiv:1710.08424 [astro-ph.SR]
109 Stellar evolution simulated with MESA 12778*
108 102 103 104 105 106 107
*Paxton et al, arXiv:1710.08424 [astro-ph.SR]
Min = 120M Min = 40M Min = 70M
109 Stellar evolution simulated with MESA 12778*
108 102 103 104 105 106 107
*Paxton et al, arXiv:1710.08424 [astro-ph.SR] Pair-instability
• The high temperatures of the pop-III stars lead to electron-positron + − 10 pair creation in the thermal plasma via γγ → e e (2me ≃ 10 K)
• Stars supported by radiation Relativistic electrons pressure Γ = ∂P/∂ρ ≈ 4/3 ( )s • Instability occurs for Γ < 4/3 Ion pressure 109 ‣ Non-relativistic electrons destabilize the star γγ → e+e− Boltzmann suppressed ‣ Rapid thermonuclear burning 102 103 104 105 106 of 16O follows
Min = 120M Min = 40M Min = 70M
109 Stellar evolution simulated with + − 10 MESA 12778* γγ → e e (2me ≃ 10 K) softens the equation of state
108 102 103 104 105 106 107
*Paxton et al, arXiv:1710.08424 [astro-ph.SR] Extremely massive
(P)PISN stars (Min > 200 M⊙)
Very, very massive stars
(Min > 90 M⊙)
Very massive stars
(Min > 50 M⊙)
Adapted from Renzo et al [2002.05077] Pair-instability and the BHMG
−3 Z = Z⊙/10 = 1.42 × 10
60
40
20
0 40 50 60 70 80 90 Croon, McDermott, JS arXiv:2007.00650 [hep-ph] JS arXiv:2007.00650 Croon, McDermott, Known physics dependence of the BHMG
• Astrophysical + nuclear + numerical uncertainties
• Most important uncertainty: 12C(α, γ)16O rate • Using updated deBoer et al rate, BHMG found at +0 51−4 M⊙ deBoer et al arXiv:1709.03144 [hep-ex] Farmer, Renzo, de Mink, Fishbach, Justham arXiv:2006.06678 [astro-ph.SR] Farmer, Renzo, de Mink, Marchant, Justham arXiv:1910.12874 [astro-ph.SR] Known physics dependence of the BHMG
• Astrophysical + nuclear + numerical uncertainties
• Most important uncertainty: 12C(α, γ)16O rate • Using updated deBoer et al rate, BHMG found at +0 51−4 M⊙ deBoer et al arXiv:1709.03144 [hep-ex] Farmer, Renzo, de Mink, Fishbach, Justham arXiv:2006.06678 [astro-ph.SR] Farmer, Renzo, de Mink, Marchant, Justham But GW190521?! arXiv:1910.12874 [astro-ph.SR] Sam McDermott Djuna Croon
What about new physics?
Eric Baxter Maria Straight Croon, McDermott, JS arXiv:2007.00650 [hep-ph] Croon, McDermott, Sakstein arXiv:2007.07889 [gr-qc] JS, Croon, McDermott, JS, Baxter arXiv:2009.01213 [gr-qc] Straight, JS, Baxter 2009.10716 [gr-qc] 18 Croon, McDermott, JS arXiv:2007.00650 [hep-ph] The BHMG and new physics Croon, McDermott, JS arXiv:2007.07889 [gr-qc]
• Scenario 1: new, light particles coupled to material in the star introduce new loss channels
• Case studies:
• the electrophilic axion ℒae = − igaeψ¯eγ5ψea (will also work with 26 2 α26 ≡ 10 gae/4π for convenience)* 1 the photophilic axion ˜μν (will also define 10 • ℒaγ = − gaγaFμν F g10 ≡ 10 gaγ 4 GeV) 2 ϵ mA′ the hidden photon μν ′μ • ℒA′γ = − Fμ′νF + Aμ′A 2 2
*Interesting in light of the XENON1T excess, arXiv:2006.09721 [hep-ex] Croon, McDermott, JS arXiv:2007.00650 [hep-ph] The BHMG and new physics Croon, McDermott, JS arXiv:2007.07889 [gr-qc]
• Scenario 1: new, light particles coupled to material in the star introduce new loss channels
Extra scenarios: large extra dimensions (d = 4 + 2) and neutrino • Case studies: magnetic moment work through essentially the same mechanism
• the electrophilic axion ℒae = − igaeψ¯eγ5ψea (will also work with 26 2 α26 ≡ 10 gae/4π for convenience)* 1 the photophilic axion ˜μν (will also define 10 • ℒaγ = − gaγaFμν F g10 ≡ 10 gaγ 4 GeV) 2 ϵ mA′ the hidden photon μν ′μ • ℒA′γ = − Fμ′νF + Aμ′A 2 2
*Interesting in light of the XENON1T excess, arXiv:2006.09721 [hep-ex] Croon, McDermott, JS arXiv:2007.00650 [hep-ph] Energy loss due to electrophilic axions
• Semi-Compton scattering, e + γ → e + a: 2 6 40 ζ6αEMgae YeT 6 erg T � = ≃ 33 α Y T F T ≡ • sC 2 4 26 e 8 deg 8 8 π mNme g⋅s ( 10 K ) • Energy loss due to photophilic axions
• Primakov effect (Z, A) + γ → (Z, A) + a 2 7 2 2 gaγT kS 2 erg kS 2 � = f[(k /2T) ] ≃ 283.16 g2 T7ρ−1 f[(k /2T) ] aγ 4π2ρ ( 2T ) S g ⋅ s 10 8 3 ( 2T ) S
• With Debye momentum k 2 ρ S = 0.166 3 Y Z2 • ( ) 3 ∑ j j 2T T8 j
Croon, McDermott, JS arXiv:2007.07889 [gr-qc] Energy loss due to hidden photons
• Plasma production, dominated by longitudinal modes (in a non- relativistic plasma)
2 2 3 2 2 2 2 ϵ m ωp ϵ m ωpT m A′ A′ 3 erg Z ϵ A′ �A′ = ≃ ≃ 1.8 × 10 T8 4π ρ eωp/T − 1 4π ρ g ⋅ s A ( 10−7 meV ) Where photons have plasma mass
4παEMne Z 2 ωp ≃ ≃ 654eV ρ3 ε me A In the limit Aµ Aµ!
Croon, McDermott, JS arXiv:2007.07889 [gr-qc] Loss rates 1010 109 108
106
104
6 108 102 Electrophilic axion: �ae ∝ T 108 109 106
104 Photophilic axion: 4 108 �aγ ∝ T 102
109 106
5 Hidden photon: 108 10 �A′ ∝ T 100 101 102 103 104 105 106 107 Croon, McDermott, JS arXiv:2007.07889 [gr-qc] JS arXiv:2007.07889 Croon, McDermott, Example track of Min = 55 M⊙ progenitor
Min = 120M Min = 40M Main nuclear reactions: Min = 70M
109 + 12C(α, γ)16O Stellar evolution simulated with MESA 12778*
108 102 103 104 105 106 107
*Paxton et al, arXiv:1710.08424 [astro-ph.SR] What does the extra energy loss do?
3. Greater energy losses lead to Min = 63 M⊙ shorter He-burning phases 2.5
2. Extra dissipation scales linearly with α26 0.17 0.16 0.15 0.14 0.13 Less time for 12C(α, γ)16O: 0.12 C/O is larger at the time of 0.11 0 20 40 60 80 100 helium depletion (HD) Helium burning The BHMG and new physics Carbon burning Oxygen burning → Enhanced losses, larger C/O at HD C/O at Enhanced losses, larger
Enhanced losses → greater progenitors collapse → larger black holes Adapted from Farmer, Renzo, de Mink, Fishbach, Justham [2006.06678] Fishbach,Mink, de Justham Renzo, from Farmer, Adapted 70 70 60 60 50 50 40 40 30 30 20 20
10 10 0 0 30 40 50 60 70 GW150914 GW151012 GW151226 GW170104 GW170608 GW170729 GW170809 GW170814 GW170818 GW170823 Croon, McDermott, JS arXiv:2007.07889 [gr-qc] JS arXiv:2007.07889 Croon, McDermott, 60 60 50 50 40 40 30 30 20 20 10 10 0 0 20 30 40 50 60 70 GW150914 GW151012 GW151226 GW170104 GW170608 GW170729 GW170809 GW170814 GW170818 GW170823 Croon, McDermott, JS arXiv:2007.00650 [hep-ph] JS arXiv:2007.00650 Croon, McDermott, 60 60 50 50 40 40 30 30 In strong tension with stellar cooling constraints but interesting complementary 20 probe in light of XENON1T 20 10 10 0 0 20 30 40 50 60 70 GW150914 GW151012 GW151226 GW170104 GW170608 GW170729 GW170809 GW170814 GW170818 GW170823 Croon, McDermott, JS arXiv:2007.00650 [hep-ph] JS arXiv:2007.00650 Croon, McDermott, 50 50 40 40 30 30
20 20
10 10 0 0 20 30 40 50 60 70 GW150914 GW151012 GW151226 GW170104 GW170608 GW170729 GW170809 GW170814 GW170818 GW170823 Croon, McDermott, JS arXiv:2007.07889 [gr-qc] JS arXiv:2007.07889 Croon, McDermott, Loss rates 1010 109 108
106
104
6 108 102 Electrophilic axion: �ae ∝ T 108 109 106
104 Photophilic axion: 4 108 �aγ ∝ T 102
109 106
5 Hidden photon: 108 10 �A′ ∝ T 100 101 102 103 104 105 106 107 Croon, McDermott, JS arXiv:2007.07889 [gr-qc] JS arXiv:2007.07889 Croon, McDermott, Example track of Min = 55 M⊙ progenitor Implications of enhanced losses
Min = 63M⊙
60
63
50
62.7
2× 108 3× 108 4× 108
40 108 109 1010 Implications of enhanced losses
Min = 63M⊙ The wind losses
60 are a bit lower
The pulsation losses 63 are much lower 50
62.7
2× 108 3× 108 4× 108
40 108 109 1010 New physics and the black hole mass gap
160 160160 160160 160
140 140140 140140 140 120 120120 120120 120
100 100100 100100 100 80 8080 8080 80 60 6060 6060 60 40 4040 4040 40
20 2020 2020 20
0 20 40 60 80 100 0 1 2 3 4 5 0 1 2 3 4 5
6 4 �ae ∝ T �aγ ∝ T �A′ ∝ T
Potentially large shifts of the mass gap!
Croon, McDermott, JS arXiv:2007.07889 [gr-qc] Heavier degrees of freedom?
Heavier degrees of freedom may instead be thermalized in the core
1010
Then, they may give rise to an instability in the same way that electron-positron pairs do 109
Equilibration time (vector):
−1 −1 2 −mA′/Tc tA′ ≃ ΓA′ ≃ (ϵ σT nee ) 108 so for ϵ = 3 × 10−12, we find 5 tA′ ≃ 10 years, a timescale similar to the lifetime of helium burning 100 101 102 103 104 105 106 107 108 109 Croon, McDermott, JS arXiv:2007.07889 [gr-qc]
Sakstein, DC, McDermott, Straight, The BHMG and new physics Baxter arXiv:2009.01213 [gr-qc] Straight, JS, Baxter 2009.10716 [gr-qc]
• Scenario 2: screened modified gravity (MG)
• Cosmic acceleration may be driven by large scale modifications of gravity • Theories need to include screening mechanisms to satisfy solar system
bounds
• Examples: chameleon, DHOST, dark matter—baryon interactions Sakstein, DC, McDermott, Straight, The BHMG and new physics Baxter arXiv:2009.01213 [gr-qc] Straight, JS, Baxter 2009.10716 [gr-qc]
• Scenario 2: screened modified gravity (MG)
ΔG G M • Unscreened galaxies: F = 1 + N 2 ( GN ) r Environment-dependent Value depends on galaxy, level of screening, and theory • Screening of galaxies depends on theory =0 in screened galaxies • Need screening maps to determine screening level
• Extra complication that is the subject of ongoing work Straight, JS, Baxter 2009.10716 [gr-qc] The BHMG and new physics
• Scenario 2: screened modified gravity (MG) • Increased local strength of gravity → need larger pressure gradient to maintain hydrostatic equilibrium → larger core temperature at fixed density • Pair instability is exacerbated →Lighter black holes
• Decreased local strength of gravity works in reverse → Heavier black holes Straight, JS, Baxter 2009.10716 [gr-qc]
LIGO/Virgo confidence regions for the location of the BHMG Straight, JS, Baxter 2009.10716 [gr-qc] A new test of the strong equivalence principle
• Change G in stars but note black holes
(no-hair theorem) Slope of the IMF
• BHMG changes but waveform doesn’t
• Compare mass gap prediction with LIGO/
Virgo data Marginalized results using first 10 detections ΔG 7% bound: +0.04 • = 0.1−0.1 GN GW190521, the impossible black holes … and Beyond the Standard Model physics
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50 60 70 80 90
JS, Croon, McDermott, Straight, Baxter arXiv:2009.01213 [gr-qc] Looking ahead…
Posterior PDFs using the first 4 BBH mergers, and assuming a power law mass distribution, −α p(m1 |α) ∝ m1
With the complete O3 data set (and beyond), the field of black hole population studies will really take off!
from Fishbach & Holz, arXiv:1709.08584 [astro.ph] To conclude,
• Gravitational waves offer an exciting new opportunity to study open questions in particle astrophysics and cosmology
• Binary mergers allow for black hole population studies
• The black hole mass gap is an exciting probe of new physics, which will come into focus in the next few years
• GW190521 constitutes an intriguing puzzle which could be (partially) explained by BSM physics
46 Sam McDermott Djuna Croon
Thank you!
[email protected] | jeremysakstein.com
Eric Baxter Maria Straight
Slide credit: Djuna Croon 47 Large black hole in LB-1?
• Last year, a 70 M⊙ black hole was reported in a binary with a high- metallicity smaller star (from the radial velocity variability of the Hα emission line, suggesting an accretion disk) • It was suggested (1911.12357) that it was formed due to the core- collapse of a high metallicity progenitor with reduced stellar winds • However, those simulations did not include pulsations (they were stopped at carbon burning) • The observation has since also been disputed (1912.04185 and 1912.03599) - apparent shifts instead originate from shifts in the luminous star’s Hα absorption line