Cosmological lithium problem: Difference between revisions

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{{Short description|Problem in astronomy}}

In [[astronomy]], the '''lithium problem''' or '''lithium discrepancy''' refers to the discrepancy between the primordial [[Abundance of the chemical elements|abundance]] of [[lithium]] as inferred from observations of metal-poor ([[Stellar population|Population II]]) [[Stellar halo|halo stars]] in our galaxy and the amount that should theoretically exist due to [[Big Bang nucleosynthesis]]+[[Wilkinson Microwave Anisotropy Probe|WMAP]] cosmic baryon density predictions of the [[Cosmiccosmic microwave background|CMB]] (CMB). Namely, the most widely accepted models of the Big Bang suggest that three times as much primordial lithium, in particular [[lithium-7]], should exist.<ref>{{cite journal |doi=10.1146/annurev-nucl-102010-130445 |title=The Primordial Lithium Problem |date=2011 |last1=Fields |first1=Brian D. |journal=Annual Review of Nuclear and Particle Science |volume=61 |pages=47–68 |arxiv=1203.3551 |bibcode=2011ARNPS..61...47F }}</ref> This contrasts with the observed abundance of isotopes of [[hydrogen]] (¹H and [[deuterium|²H]]) and [[helium]] ([[helium-3|³He]] and [[helium-4|⁴He]]) that are consistent with predictions.<ref name=HouStats>{{cite journal |last1=Hou |first1=S. Q. |last2=He |first2=J.J. |last3=Parikh |first3=A. |last4=Kahl |first4=D. |last5=Bertulani |first5=C.A. |last6=Kajino |first6=T. |last7=Mathews |first7=G.J. |last8=Zhao |first8=G. |date=2017 |title=Non-extensive statistics to the cosmological lithium problem |journal=The Astrophysical Journal |volume=834 |issue=2 |pages= 165|doi=10.3847/1538-4357/834/2/165 |bibcode=2017ApJ...834..165H |arxiv=1701.04149 |s2cid=568182 |doi-access=free }}</ref> The discrepancy is highlighted in a so-called "Schramm plot", named in honor of astrophysicist [[David Schramm (astrophysicist)|David Schramm]], which depicts these primordial abundances as a function of cosmic baryon content from standard [[Big Bang nucleosynthesis|BBN]] predictions.

[[File:Schramm plot BBN review 2019.png|thumb|400px|This "Schramm plot"<ref>{{cite journal | last1=Tanabashi | first1=M. | last2=Hagiwara | first2=K. | last3=Hikasa | first3=K. | last4=Nakamura | first4=K. | last5=Sumino | first5=Y. | last6=Takahashi | first6=F. | last7=Tanaka | first7=J. | last8=Agashe | first8=K. | last9=Aielli | first9=G. | last10=Amsler | first10=C. | display-authors=5|collaboration=Particle Data Group| title=Review of Particle Physics | journal=Physical Review D | publisher=American Physical Society (APS) | volume=98 | issue=3 | date=2018-08-17 | issn=2470-0010 | doi=10.1103/physrevd.98.030001 | page=030001| bibcode=2018PhRvD..98c0001T |doi-access=free| hdl=10044/1/68623 | hdl-access=free }} and 2019 update.</ref> depicts primordial abundances of ⁴He, D, ³He, and ⁷Li as a function of cosmic baryon content from standard BBN predictions. CMB predictions of ⁷Li (narrow vertical bands, at 95% [[confidence level|CL]]) and the BBN D&nbsp;+&nbsp;⁴He concordance range (wider vertical bands, at 95% CL) should overlap with the observed light element abundances (yellow boxes) to be in agreement. This occurs in ⁴He and is well constrained in D, but is not the case for ⁷Li, where the observed Li observations lie a factor of 3−4 below the BBN+WMAP prediction.]]

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==Origin of lithium==

Minutes after the Big Bang, the universe was made almost entirely of hydrogen and helium, with trace amounts of lithium and beryllium, and negligibly small abundances of all heavier elements.<ref name="habitable"/><ref>{{cite web|url=https://physics.unc.edu/the-cosmological-lithium-problem/|title=Cosmological lithium problem|website=University of North Carolina|date=14 September 2020 }}</ref>

===Lithium synthesis in the Big Bang===

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Firstly, incorrect or missing reactions could give rise to the lithium problem. For incorrect reactions, major thoughts lie within revision to [[cross section (physics)|cross section]] errors and standard thermonuclear rates according to recent studies.<ref>{{Cite journal|last1=Angulo|first1=C.|last2=Casarejos|first2=E.|last3=Couder|first3=M.|last4=Demaret|first4=P.|last5=Leleux|first5=P.|last6=Vanderbist|first6=F.|last7=Coc|first7=A.|last8=Kiener|first8=J.|last9=Tatischeff|first9=V.|last10=Davinson|first10=T.|last11=Murphy|first11=A. S.|date=September 2005|title=The 7Be(d,p)2α Cross Section at Big Bang Energies and the Primordial 7Li Abundance|journal=Astrophysical Journal Letters|language=en|volume=630|issue=2|pages=L105–L108|doi=10.1086/491732|arxiv=astro-ph/0508454 |bibcode=2005ApJ...630L.105A |issn=0004-637X|doi-access=free}}</ref><ref>{{Cite journal|last1=Boyd|first1=Richard N.|last2=Brune|first2=Carl R.|last3=Fuller|first3=George M.|last4=Smith|first4=Christel J.|date=November 2010|title=New nuclear physics for big bang nucleosynthesis|url=https://ui.adsabs.harvard.edu/abs/2010PhRvD..82j5005B/abstract|journal=Physical Review D |language=en|volume=82|issue=10|pages=105005|doi=10.1103/PhysRevD.82.105005|issn=1550-7998|arxiv=1008.0848|bibcode=2010PhRvD..82j5005B |s2cid=119265813 }}</ref>

Second, starting from [[Fred Hoyle]]'s discovery of a [[Resonance (particle physics)|resonance]] in [[carbon-12]], an important factor in the [[triple-alpha process]], resonance reactions, some of which might have evaded experimental detection or whose effects have been underestimated, become possible solutions to the lithium problem.<ref>{{Cite journal|last1=Hammache|first1=F.|last2=Coc|first2=A.|last3=de Séréville|first3=N.|last4=Stefan|first4=I.|last5=Roussel|first5=P.|last6=Ancelin|first6=S.|last7=Assié|first7=M.|last8=Audouin|first8=L.|last9=Beaumel|first9=D.|last10=Franchoo|first10=S.|last11=Fernandez-Dominguez|first11=B.|date=December 2013|title=Search for new resonant states in 10C and 11C and their impact on the cosmological lithium problem|url=https://ui.adsabs.harvard.edu/abs/2013PhRvC..88f2802H/abstract|journal=Physical Review C|language=en|volume=88|issue=6|pages=062802|doi=10.1103/PhysRevC.88.062802|issn=0556-2813|arxiv=1312.0894|bibcode=2013PhRvC..88f2802H |s2cid=119110688 }}</ref><ref>{{Cite journal|last1=O'Malley|first1=P. D.|last2=Bardayan|first2=D. W.|last3=Adekola|first3=A. S.|last4=Ahn|first4=S.|last5=Chae|first5=K. Y.|last6=Cizewski|first6=J. A.|author6-link= Jolie Cizewski |last7=Graves|first7=S.|last8=Howard|first8=M. E.|last9=Jones|first9=K. L.|last10=Kozub|first10=R. L.|last11=Lindhardt|first11=L.|date=October 2011|title=Search for a resonant enhancement of the 7Be + d reaction and primordial 7Li abundances|url=https://ui.adsabs.harvard.edu/abs/2011PhRvC..84d2801O/abstract|journal=Physical Review C|language=en|volume=84|issue=4|pages=042801|doi=10.1103/PhysRevC.84.042801|bibcode=2011PhRvC..84d2801O |issn=0556-2813}}</ref> These include:

{| border="0"

|- style="height:2em;"

|{{nuclide|link=yes|beryllium|7}}&nbsp;||+&nbsp;||{{nuclide|link=yes|hydrogen|2}}&nbsp;||→&nbsp;||{{nuclide|link=yes|boron|9}}&nbsp;*

|- style="height:2em;"

|{{nuclide|link=yes|beryllium|7}}&nbsp;||+&nbsp;||{{nuclide|link=yes|hydrogen|3}}&nbsp;||→&nbsp;||{{nuclide|link=yes|boron|10}}&nbsp;*

|-

|{{nuclide|link=yes|beryllium|7}}&nbsp;

| +&nbsp;

|{{nuclide|link=yes|helium|3}}&nbsp;

|→&nbsp;

|{{nuclide|link=yes|carbon|10}}&nbsp;*

|}Experimental and theoretical analyses rule out the first and third reactions.<ref name="o946">{{cite journal |last=Cyburt |first=Richard H. |last2=Fields |first2=Brian D. |last3=Olive |first3=Keith A. |last4=Yeh |first4=Tsung-Han |date=2016-02-23 |title=Big bang nucleosynthesis: Present status |url=https://link.aps.org/accepted/10.1103/RevModPhys.88.015004 |journal=Reviews of Modern Physics |volume=88 |issue=1 |page= |doi=10.1103/RevModPhys.88.015004 |issn=0034-6861 |access-date=2025-03-30 |doi-access=free|arxiv=1505.01076 }}</ref>

''[[BBC Science Focus]]'' wrote in 2023 that "recent research seems to completely discount" such theories; the magazine held that mainstream lithium nucleosynthesis calculations are probably correct.<ref name=BBC2023>{{cite news |url=https://www.sciencefocus.com/science/lithium-shortage-universe/ |title=The lithium problem: Why the element keeps disappearing |work=BBC Science Focus Magazine |date=16 June 2023 |author=Alastair Gunn |access-date=17 June 2023}}</ref>

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* [[List of unsolved problems in physics]]

* [[Lithium burning]]

==Further reading==

* {{cite journal |last1=Fields |first1=Brian D. |title=The Primordial Lithium Problem |journal=Annual Review of Nuclear and Particle Science |volume=61 |year=2011 |pages=47–68 |doi=10.1146/annurev-nucl-102010-130445 |arxiv=1203.3551|bibcode=2011ARNPS..61...47F }}

* {{cite journal |doi=10.1103/PhysRevD.83.063006 |title=Resonant destruction as a possible solution to the cosmological lithium problem |date=2011 |last1=Chakraborty |first1=Nachiketa |last2=Fields |first2=Brian D. |last3=Olive |first3=Keith A. |journal=Physical Review D |volume=83 |issue=6 |page=063006 |arxiv=1011.0722 |bibcode=2011PhRvD..83f3006C }}

* {{cite journal |doi=10.1142/S0218301312500048 |title=Resonant Enhancement of Nuclear Reactions as a Possible Solution to the Cosmological Lithium Problem |date=2012 |last1=Cyburt |first1=Richard H. |last2=Pospelov |first2=Maxim |journal=International Journal of Modern Physics E |volume=21 |issue=1 |pages=1250004-1-1250004-13 |arxiv=0906.4373 |bibcode=2012IJMPE..2150004C }}

* {{cite journal |last1=Hou |first1=S. Q. |last2=Yan |first2=H. L. |last3=Li |first3=X. Y. |last4=Zhou |first4=X. H. |last5=Sun |first5=B. |title=Non-Extensive Statistics to the Cosmological Lithium Problem |journal=The Astrophysical Journal |volume=834 |issue=2 |year=2017 |pages=165 |doi=10.3847/1538-4357/834/2/165 |doi-access=free |arxiv=1701.03700|bibcode=2017ApJ...834..165H }}

==References==