Brian Fields ESO Cosmic Duologue | 26 Jan 2021 - The Primordial Li thium Pr oblem
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
A Bitter Pill:
The Primordial Li thium
Pr oblem
Brian Fields
ESO Cosmic Duologue | 26 Jan 2021
Big Bang Nucleosynthesis:
A Symphony of Fundamental Forces
• BBN: unique arena
Gravity
– all four fundamental Weak EM Strong
forces participate
• BBN: unique
testbed
– probes all
fundamental
interactions
Standard BBN
Gravity = General Relativity
Microphysics: Standard Model of Particle Physics
§ Nν = 3 neutrino species
§ mν ! 1 MeV
§ Left handed neutrino couplings only
§ neutrinos non-degenerate: and not
Kinetic equilibrium: Maxwell-Boltzmann nuclei
Dark Matter and Dark Energy
o d e ls
§ Present (presumably) but non-interacting B N m
a rd B i o n s
S ta n d u m p t
η ≡N n -
nbaryon
o e s s
aconst
Homogeneous U. x t he s
Spatially
ys i c s
re
n la
γ
e w p h
Ø Expansion adiabatic
! " ! " test n! "
nB nB nB
= =
nγ BBN nγ CMB nγ today
• gives baryon density
Making Primordial Lithium
in Standard BBN
• SBBN Lithium = 7Li. 6Li negligible
• 7Li mostly made as 7Be
much later
• Production:
• Destruction: neutrons are
Li poison!
baryon density ≠bh2
Ypp = ρ4 He /ρbary
10°2
0.26 Stanard BBN
0.25 Predictions
Pitrou talk
Y
0.24
0.23
Curve Widths:
abundances
°3
10
Theoretical uncertainty
D/H
nuclear cross sections
10°4
BDF, Olive, Yeh, Young 2020
He/H
Pitrou+ 2018
10°5
Cyburt, BDF, Olive, Yeh 2015
3
Descouvement poster
10°9 Cyburt, BDF, Olive 2008
Cyburt 2004
Li/H
Coq et al 2004
Serpico et al 2005
7
Cyburt, BDF, Olive 2001
10°10
Krauss & Romanelli 1988
10°10 Note D-Li
10°9 anti correlation
Smith, Kawano, Malaney 1993
baryon-to-photon ratio ¥ = nb/n∞ Hata et al 1995
Copi, Schramm, Turner 1995
baryon density
Light Elements: Sites
Deuterium
– in z~3 galaxies backlit by quasars
– New! leap in precision: Pettini, Cooke+ 2013-2019
4He
– ionized gas (HII regions) in metal-poor galaxies
– New! CMB damping tail: SPT 2011,2012; Planck 2013-2018
7Li
– metal-poor halo stars in Milky Way
– Newish! now also extragalactic observations
3He
– hyperfine in Milky Way HII regions Rood, Wilson,
Bania+
– no low-metal data; not used for cosmology
0.27
baryon density parameter ≠Bh2
10°2 Testing BBN:
perfect observation Light Element
He mass fraction
Observations
0.26
0.25 all observations
0.24 actual observation
Theory:
0.23
4
• 1 free parameter predicts
10°3
• 4 nuclides: D, 3He, 4He, 7Li
D/H
C
M Observations:
10°4 B
• 3 nuclides with precision: D, 4He, 7Li
He/H
10°5
Comparison:
3
★each nuclide selects baryon density
10°9 ★overconstrained--nontrivial test!
Result:
Li/H
★rough concordance!
7
★but not in detail! D and 7Li disagree
10°10 need a tiebreaker
10°10 10°9
baryon-to-photon ratio ¥ = nb/n∞
Battle of the Baryons: II
CMB New World Order
Cyburt, BDF, Olive 2003, …, Yeh, Olive, BDF 2021
Planck baryon density very precise
⌦B h2 = 0.022298 ± 0.000020
10
⌘ = (6.104 ± 0.058) ⇥ 10
i.e., a sub-1% measurement!
New strategy to test BBN:
✓ use Planckηcmb as BBN input
✓ predict all lite elements
with appropriate error propagation
✓ compare with observations
Battle of the Baryons: II
A Closer Look
Cyburt, BDF, Olive 2003, 2008, 2015; BDF, Olive, Yeh, Young 2020
P lanck baseline (N∫ = 3) + BBN
Likelihoods 1.0 (a) (b)
purple: BBN+CMB predictions 0.8
Likelihood
yellow: observations 0.6
0.4
0.2
0.0
Results: 0.23 0.24 0.25 0.26 0 1 2 3 4
Yp 5
10 £ D/H
Ø D excellent!
1.0 (c) (d)
Ø 4He great!
0.8
Likelihood
Ø 7Li poor!
0.6
- observation ~ theory/4 0.4
- 4-5 sigma discrepancy 0.2
- Lithium Problem 0.0
7 8 9 10 11 12 1 2 3 4 5 6
106 £ 3 He/H 1010 £ 7 Li/H
Lithium Strategy I:
No Worries
Two out of three ain’t badBBN Beyond the Standard Model:
Probing Particle Physics
baryon density ≠bh22
baryon
10density
°2 ≠b h
0.26 °2
10
0.26
0.25
Lite elements probe cosmic expansion history 0.25
p p
Radiation domination
YY
0.24
0.24
(expansion)2 = H 2 ∼ Gρtot,rel 0.23
BDF, Olive, Yeh, Young 2020
0.23
Controlled by 10°3
10°3
D/H
D/H
ρtot,rel = ρEM + Nν,eff ρν ν̄ 10°4
10°4
3 3 He/H
He/H
Observed abundances constrain 10°5
10°5
anything that
°9
✓ Couples to gravity 10
10°9
✓ Perturbs relativistic energy density
7 7 Li/H
Li/H
Stiegman, Schramm, & Gunn 77
°10
10
10°10
°10 °9
10
10°10 10°9
10
baryon-to-photon ratio ¥
baryon-to-photon ratio ¥==n
nbb/n
/n∞∞5.5 6.0 6.5 7.0 5.0 5.5 6.0 6.5
baryon-to-photon ratio, 1010 £ ¥ Planck 2018 + BBN baryon-to-photon ratio, 1010 £
BDF, Olive, Yeh, Young 2020
Both Yp & D Obs. Constraints
Tsung-Han Yeh —– 68.27%
葉宗翰
5 —– 95.45% Concordance!
—– 99.73%
Neutrino Number, N∫
4
Standard Particle Physics
3
2
BBN+Yp+D
CMB+BBN+Yp+D
1
5.0 5.5 6.0 6.5 7.0
baryon-to-photon ratio, 1010 £ ¥Likeli
0.4
0.2
Lithium Strategy II:
0.0
0.23
Worry
0.24 0.25
Yp
0.26 0 1 2 3
105 £ D/H
4 5
1.0 (c) (d)
0.8
Likelihood
0.6
0.4
0.2
0.0
7 8 9 10 11 12 1 2 3 4 5 6 7
6 3 10 7
10 £ He/H 10 £ Li/HPrimordial Lithium
CMB+BBN prediction
Observe in primitive stars
(Pop II)
lithium abundances
Li versus Fe evolution
Plateau at low Fe Spite & Spite 82
★ Li is primordial
But is the plateau at Lip?
• LiPlanck/Liobs ~ 4
• Why?
metallicity = “time”P lanck baseline (N∫ = 3) + BBN
Lithium Problem Overview 1.0
0.8
(a) (b)
Likelihood
0.6
0.4
standard standard standard
0.2
observed
particle nuclear cosmology
0.0
0.23 0.24 0.25 0.26 0 1 lithium
2 3 4 5
physics physics Yp 5
10 £ D/H
1: n ! p e ⌫
2: n(p, )d
3: d(d, p)t 7
1.0 (c) (d)
Be
4: d(p, )3 He
5: d(d, n)3 He ✓ @ 12 0.8
Likelihood
6: 3 He(n, p)t @R
@
11
7: t(d, n)4 He 7
Li
8: d(d, )4 He
13 0.6
9: 3 He(d, p)4 He ✓
10: t(↵, )7 Li ⇡
11: 4 He(↵, )7 Be 3
He
9 - 4 He 0.4
10
12: 7 Be(n, p)7 Li 8
13: 7 Li(p, ↵)4 He 66@ ✓ 6
4 5 @6 7
R
@
1 - 2d - 3t
0.2
H 2 3
6
1 0.0
1
n
7 8 9 10 11 12 1 2 3 4 5 6 7
6 3 10 7
10 £ He/H 10 £ Li/H
Solutions: one of these is wrong 1Astrophysics:
Nuclear Meltdown
Sbordone+ 2010
‣ huge increase in CMB+BBN prediction
scatter at low lithium desert?
[Fe/H]
‣ at least some lithium abundances
stars efficiently
eat lithium
‣ why does
meltdown “turn
on”?
‣ no points scatter
up to BBN+CMB
abundance metallicity = “time”Nuclear Physics:
Hoyle’s Revenge?
Cyburt & Pospelov 2009 Nachiketa Chakraborty
✴ “sub-dominant” Li reactions
important if narrow resonance
missed
cf Hoyle state in 12C burning
✴ proposal: 7Be+d inelastic Problem solved!?
Chakraborty, BDF, & Olive
2011
✴ systematic study of all A=7
destruction rxns
✓ confirms 7Be+d
Experiment Says:
9B*
✓ even better: 3He+7Be 10C*
t+7Be 10B* Not there!
10C*:Hammache+ 2013
9Be*: O’Malley+ 2011Lithium Problem:
New Physics Solutions
Li Solutions Beyond the Standard Model
★strategy: new process changes light elements
★bonus: perturbation physically motivated
★goal: fix 7Li discrepancy
★ challenge: retain D, 4He success
• D vs Li anticorrelation is quite general
n+7Be destruction inevitably changes D
• D precision < 1% — no room for mischief!New Physics Example:
Could Lithium Be SUSY-licious?
Cyburt, Ellis, BDF, Luo, Olive, Spanos 2012
Supersymmetry
complex dark sector SUSY Li sweetspot
decays in early U circa 2012
Light elements are a
strong SUSY probe
✓ rule out much parameter space Higgs mass
✓ complementary to LHC
Illustrates tight links Latest D/H says:
among nucleo-cosmo- Sweetspot gone sour:
astro-particle physics
Li window closed!The Lithium Problem: Thoughts on the Way Forward • New Physics solutions challenged by D precision – if new physics, finely tuned? – yet dark matter non-detection invites new ideas • Cosmology solutions face CMB LCDM consistency • Nuclear Experiment lags observations! • Stellar Models: – also delicately tuned – why does meltdown start and stop? – why small scatter along Spite plateau? – do we understand Li pre-main sequence? • Observations: 6Li — is it even present in halo stars? intererstellar Li as depletion and isotope probe Ask me: Philosophize? new physics ideas? deuterium status? 6Li?
Director’s Cut Extras
Image Credit: Planck 2015New Physics Lithium Solutions
an Incomplete Survey
• Particle Physics Beyond the Standard Model
– decaying particles Supersymmetry Cyburt+ 2012
– mirror neutrons Coc+ 2013
– magnetic fields+decays Yamazaki+ 2014
– lepton asymmetry (degenerate neutrinos) Makki+ 2019
– light particles with nucleon interactions Goudelis+ 2016
– sterile neutrinos Salvati+ 2016
– axion quark nuggets Flambaum+ 2019
– Stable 8Be Scherrer+ 2017
– Non-extensive statistics Hou+ 2017
Many now excluded by
• Evolving Fundamental Constants
– see Martins talk
precision D observations
• Nonstandard Cosmology
– Lithium diffusion after recombination Pospelov 2012
– “Hubble bubble” of inhomogeneous abundances Regis+ 2010
– Cosmic deuterium destruction via early stellar processing Piau+ 2006
– Nonthermal “cosmic rays” during BBN Kang+ 2019The Cosmic Microwave Background: CMB
A Powerful New Baryometer
CMB ∆T! independent measure of ΩB
Twitter version: in recombining plasma
‣ baryon gravity boosts compression
‣ baryon inertia damps rarefaction peaks
BBN vs CMB: fundamental test
of cosmologyStandard BBN Tested With CMB Only
Planck Baryons & Helium!
New! e!
m a c ulat
Im ically
C o sm
!
clean
Contours:
Planck
Curve:
Standard BBN
zero parameters!You can also read
