Observational Bounds on Fine-Structure Constant Variations| Observational Bounds on Fine-Structure Constant Variations |
In General > s.a. fine-structure constant.
* Idea: Support for the possibility
is mixed; Absorption spectra of interstellar matter have led to claims both for and
against variations of α.
* Methods: Astrophysical observations
determine shifts in α by comparing the spectra of light from 3 to
10 billion years ago to those from current laboratory measurements; Atomic clock
measurements compare the frequencies of two atomic transition lines, either on the
same atom or on different atoms, over time.
* History: At one point Eddington
asserted that the fine structure constant was, for numerological reasons, exactly
1/137.
* 1997:
Δ(gpα2)
/ (gpα2) < 5
× 10−6 at z = 0.25,
0.68; Δα/α ≤ 2 ×
10−4 for atoms at z > 1.
* 2000:
α·/α ≤
3.5 × 10−15/yr out to
t0−t ~ 4.8 Gyr.
* 2001: Δα/α
~ 10−5 over 12 ×
109 yr (4.1-σ effect), from metal absorption
line spacings in gas clouds, propto α2.
* 2003: Δα/α
< (−2 ± 1.2) × 10−4 for
quasars with 0.16 < z < 0.80, from O III emission lines.
* 2004:
Δα/α = (−0.06 ± 0.06) ×
10−5 for Mg II at 0.4 < z <
2.3, and results for Si IV at 1.59 < z < 2.92, consistent with 0;
α·/α ≤ 2.0 ×
10−15/yr (1-σ, present).
* 2005: There are still discrepancies, with
the deepest data showing an increase by 6 × 10−9
over 12 × 1012 yr, and other data consistent
with no change; One possibility is that α varied earlier and no longer
varies; Δα/α = (−0.07 ± 0.84) ×
10−6 for Fe II at z = 1.15.
* 2006: Still no agreement
on effect; Δα/α = (0.05 ± 0.24) ×
10−6 at z = 1.1508.
* 2007: Change between
recombination (1012 < z < 1115) and now is −0.039
< Δα < 0.010 at 95% c.l., from WMAP3 data.
* 2008: Researchers at NIST
have concluded that α is not changing to within 1.6 ×
10−17 per year.
* 2009: WMAP5 data give
α/α0
= 0.987 ± 0.012 at 68% c.l., and 1.001 ± 0.007 at 68% including
H0 constraints from HST.
* 2010: Data from the natural Oklo
reactor give α·/α
≤ 5.0 × 10−18/yr.
* 2012: Evidence for a dipole pattern with
amplitude (1.1 ± 0.2) × 10−6/GLyr
proportional to lookback time, significant at the 4.2-σ confidence level.
* 2014: No significant
change seen in the redshift range z = 0.7 – 1.5.
* 2016: No significant
change seen in the redshift range z = 1.0 – 2.4.
* 2020: No significant
change seen in the redshift range z = 5.5 – 7.1.
@ General references: Kraiselburd et al A&A(13)-a1307 [update];
Alves et al PLB(17)-a1704 [upcoming experiments].
@ Spectral lines: Webb & al PRL(99)ap/98,
PRL(01)ap/00;
Varshalovich et al PS(01)phy/00;
Murphy et al MNRAS(01)ap/00,
ASS(03)ap/02-proc [details],
MNRAS(03)ap;
Darling PRL(03) [OH microwave transitions];
Webb pw(03)apr [rev];
Bahcall et al ApJ(04)ap/03 [O III];
Srianand et al PRL(04)ap,
criticism Murphy et al PRL(07)-a0708;
Angstmann et al PRA(04)ap [bounds];
Chand et al A&A(04)ap [Mg II],
A&A(05)ap/04 [Si IV];
Peik et al PRL(04);
Dzuba & Flambaum PRA(05)ap;
Grupe et al AJ(05)ap;
Levshakov et al IAU(05)ap-in [Fe II, z = 1.15, SIDAM];
Chand et al A&A(06)ap;
Murphy et al MNRAS(08)ap/06;
Khatri & Wandelt PRL(07)ap
+ pw(07)mar,
comment Flambaum & Porsev a1004,
reply PRL(10)-a1007 [effect on 21-cm radiation];
King et al a0910-proc [Monte Carlo methods];
Albareti et al MNRAS(15)-a1501 [13k quasar spectra at z < 1].
@ Spectral lines, no evidence:
Drinkwater et al IAP-ap/97,
MNRAS(98)ap/97,
Carilli et al PRL(00)ap
+ pn(00)dec [21-cm H line];
Levshakov LNP-ap/03;
Quast et al A&A(04)ap/03 [Fe II];
Molaro et al IAU(05)ap,
EPJST(08)-a0712 [Fe II];
Lentati et al MNRAS(13)-a1211;
Leefer et al PRL(13) [using atomic dysprosium];
Songaila & Cowie ApJ(14)-a1406;
Huntemann et al PRL(14),
Godun et al PRL(14) [atomic clock measurements];
Murphy et al MNRAS(16)-a1606 [Zn and Cr quasar absorption lines];
Murphy et al MNRAS(17)-a1708;
Wilczynska et al sAdv-a2003.
@ From cmb: Hannestad PRD(99)ap/98;
Kaplinghat et al PRD(99);
Avelino et al PRD(01)ap [bounds];
Martins ap/02-proc [bounds];
Rocha et al NAR(03)ap-proc,
MNRAS(04)ap/03 [WMAP, bounds];
Ichikawa et al PRD(06)ap;
Stefanescu NA(07)-a0707 [WMAP 3-year data];
Mosquera et al A&A(08)-a0707 [and Bekenstein model];
Scóccola et al PLB(08)-a0809,
Nakashima et al PTP(08)-a0810,
Scóccola et al a0910-proc [WMAP 5-year data];
Menegoni et al PRD(09)-a0909;
Nakashima et al JCAP(10).
@ Lab experiments: Livio & Stiavelli ApJL(98)ap;
Marion et al PRL(03)phy/02 [atomic fountain clock];
Nguyen et al PRA(04) [dysprosium lines];
Barrow & Shaw PRD(08)-a0806 [stronger constraints];
news quanta(18)apr [atomic clocks and search for dark matter].
@ Oklo reactor:
Lamoreaux & Torgerson PRD(04);
Onegin MPLA(12)-a1010;
Davis & Hamdan PRC(15)-a1503;
Hamdan & Dabis a1510-conf.
@ In gravitational fields: Berengut et al PRL(13)-a1305 [bounds on variation];
Bambi JCAP(14)-a1308,
Preval et al a1410-proc [strong fields];
Bainbridge et al Univ(17)-a1702-proc [white dwarf stars];
news sn(20)feb [no change in strong gravity].
@ Related topics:
Fujii & Iwamoto PRL(03) [Re/Os decay rate],
MPLA(05) [dating meteorites];
Centurión et al a0910-proc [calibration issues];
Galli PRD(13)-a1212 [from galaxy cluster X-ray emission];
Onegin a1412;
Holanda et al JCAP(16)-a1510 [galaxy clusters];
> s.a. tests of the equivalence principle.
Spatial Variation
* 2016: There are indications
of a spatial variation of α at a level of a few parts per million,
with a dipole providing a statistically good fit to the data.
@ References: Webb et al PRL(11)-a1008
+ news tb(11)oct,
sci(11)nov;
King et al MNRAS(12)-a1202 [evidence for dipole pattern];
Berengut et al A&A(12)-a1203;
Olive et al PRD(12)-a1204 [and dilatonic domains];
Cameron & Pettitt a1207/MNRAS,
a1309/MNRAS [skeptical interpretation];
Pinho & Martins PLB(16)-a1603,
de Martino et al Univ(16)-a1612-conf [updated constraints].
main page
– abbreviations
– journals – comments
– other sites – acknowledgements
send feedback and suggestions to bombelli at olemiss.edu – modified 5 apr 2020