Limits from Astrophysics and Cosmology

Effective Number of Light ${{\mathit \nu}}$ Types

INSPIRE   PDGID:
S007N
“Light” means here with a mass $<$ about 1 MeV. The quoted values correspond to N$_{{\mathrm {eff}}}$, where N$_{{\mathrm {eff}}}$ = 3.045 in the Standard Model with N$_{{{\mathit \nu}}}$ = 3. See also reviews on "Big-Bang Nucleosynthesis" and "Neutrinos in Cosmology."
VALUE CL% DOCUMENT ID TECN  COMMENT
• • We do not use the following data for averages, fits, limits, etc. • •
$3.12$ $\pm0.38$ 95 1
BRIEDEN
2022
COSM BOSS, eBOSS, CMB
$2.90$ $\pm0.15$ 68 2
KUMAR
2022
COSM BOSS + CMB
$2.89$ $\pm0.14$ 68 3
YEH
2022
COSM BBN + CMB
$2.99$ $\pm0.17$ 68 4
AGHANIM
2020
COSM
$2.84$ $\pm0.15$ 68 5
FIELDS
2020
COSM BBN
$2.88$ $\pm0.17$ 68 6
IVANOV
2020
COSM Planck and BOSS
$\text{2.3 - 3.2}$ 95 7
VERDE
2017
COSM
$2.88$ $\pm0.16$ 68 8
CYBURT
2016
COSM BBN
$2.88$ $\pm0.20$ 95 9
ROSSI
2015
COSM
$3.3$ $\pm0.5$ 95 10
ADE
2014
COSM Planck
$3.78$ ${}^{+0.31}_{-0.30}$ 11
COSTANZI
2014
COSM
$3.29$ $\pm0.31$ 12
HOU
2014
COSM
$<3.80$ 95 13
LEISTEDT
2014
COSM
$<4.10$ 95 14
MORESCO
2012
COSM
$<5.79$ 95 15
XIA
2012
COSM
$<4.08$ 95
MANGANO
2011
COSM BBN
$\text{0.9 - 8.2}$ 16
ICHIKAWA
2007
COSM
$\text{3 - 7}$ 95 17
CIRELLI
2006
COSM
$\text{2.7 - 4.6}$ 95 18
HANNESTAD
2006
COSM
$\text{3.6 - 7.4}$ 95 17
SELJAK
2006
COSM
$<4.4$ 19
CYBURT
2005
COSM
$<3.3$ 20
BARGER
2003C
COSM
$\text{1.4 - 6.8}$ 21
CROTTY
2003
COSM
$\text{1.9 - 6.6}$ 21
PIERPAOLI
2003
COSM
$\text{2 - 4}$
LISI
1999
COSM BBN
$<4.3$
OLIVE
1999
COSM BBN
$<4.9$
COPI
1997
Cosmology
$<3.6$
HATA
1997B
High D/H quasar abs.
$<4.0$
OLIVE
1997
BBN; high ${}^{4}\mathrm {He}$ and ${}^{7}\mathrm {Li}$
$<4.7$
CARDALL
1996B
COSM High D/H quasar abs.
$<3.9$
FIELDS
1996
COSM BBN; high ${}^{4}\mathrm {He}$ and ${}^{7}\mathrm {Li}$
$<4.5$
KERNAN
1996
COSM High D/H quasar abs.
$<3.6$
OLIVE
1995
BBN; ${}\geq{}3$ massless ${{\mathit \nu}}$
$<3.3$
WALKER
1991
Cosmology
$<3.4$
OLIVE
1990
Cosmology
$<4$
YANG
1984
Cosmology
$<4$
YANG
1979
Cosmology
$<7$
STEIGMAN
1977
Cosmology
PEEBLES
1971
Cosmology
$<16$ 22
SHVARTSMAN
1969
Cosmology
HOYLE
1964
Cosmology
1  BRIEDEN 2022 combines large scale structure data from BOSS and eBOSS including the shape of the matter power spectrum with Planck CMB data.
2  KUMAR 2022 combine the reconstructed galaxy power spectrum from BOSS data with Planck CMB data.
3  YEH 2022 combines Planck 2018 CMB data with BBN and observations of deuterium and ${}^{}\mathrm {Helium}$-4. Supersedes FIELDS 2020.
4  AGHANIM 2020 best fit on number of neutrino types is based on Planck data combined with lensing and baryon acoustic oscillations (BAO). Without BAO, they find $2.89$ ${}^{+0.18}_{-0.19}$. Several other values are quoted using different combinations of data.
5  FIELDS 2020 combines Planck 2018 CMB data with BBN and observations of deuterium and Helium-4.
6  IVANOV 2020 combines 2018 Planck CMB data with baryon acoustic oscillation data from BOSS. This study is based on a full-shape likelhood for the redshift-space galaxy power spectrum of the BOSS data.
7  Uses Planck Data combined with an independent standard measure of distance to the sound horizon to set a limit on the total number of neutrinos. Only CMB and early-time information are used.
8  CYBURT 2016 combines Planck 2015 CMB data with BBN and observations of deuterium and Helium-4.
9  ROSSI 2015 sets limits on the number of neutrino types using BOSS Lyman alpha forest data combined with Planck CMB data and baryon acoustic oscillations.
10  Fit to the number of neutrino degrees of freedom from Planck CMB data along with WMAP polarization, high L, and BAO data.
11  Fit to the number of neutrinos degrees of freedom from Planck CMB data along with BAO, shear and cluster data.
12  Fit based on the SPT-SZ survey combined with CMB, BAO, and ${{\mathit H}_{{{0}}}}$ data.
13  Constrains the number of neutrino degrees of freedom (marginalizing over the total mass) from CMB, CMB lensing, BAO, and galaxy clustering data.
14  Limit on the number of light neutrino types from observational Hubble parameter data with seven-year WMAP data, SPT, and the most recent estimate of ${{\mathit H}_{{{0}}}}$. Best fit is $3.45$ $\pm0.65$.
15  Limit on the number of light neutrino types from the CFHTLS combined with seven-year WMAP data and a prior on the Hubble parameter. Best fit is $4.17$ ${}^{+1.62}_{-1.26}$. Limit is relaxed to $3.98$ ${}^{+2.02}_{-1.20}$ when small scales affected by non-linearities are removed.
16  Constrains the number of neutrino types from recent CMB and large scale structure data. No priors on other cosmological parameters are used.
17  Constrains the number of neutrino types from recent CMB, large scale structure, Lyman-alpha forest, and SN1a data. The slight preference for $\mathit N_{{{\mathit \nu}}}$ $>$ 3 comes mostly from the Lyman-alpha forest data.
18  Constrains the number of neutrino types from recent CMB and large scale structure data. See also HAMANN 2007.
19  Limit on the number of neutrino types based on ${}^{4}\mathrm {He}$ and D/H abundance assuming a baryon density fixed to the WMAP data. Limit relaxes to 4.6 if D/H is not used or to 5.8 if only D/H and the CMB are used. See also CYBURT 2001 and CYBURT 2003.
20  Limit on the number of neutrino types based on combination of WMAP data and big-bang nucleosynthesis. The limit from WMAP data alone is 8.3. See also KNELLER 2001. $\mathit N_{{{\mathit \nu}}}{}\geq{}$3 is assumed to compute the limit.
21  95$\%$ confidence level range on the number of neutrino flavors from WMAP data combined with other CMB measurements, the 2dfGRS data, and HST data.
22  SHVARTSMAN 1969 limit inferred from his equations.
References