Limits from Astrophysics and Cosmology

Effective Number of Light ${{\boldsymbol \nu}}$ Types INSPIRE search

(``Light'' means $<$ about 1 MeV). The quoted values correspond to N$_{{\mathrm {eff}}}$, where N$_{{\mathrm {eff}}}$ = 3.046 in the Standard Model with N$_{{{\mathit \nu}}}$ = 3. See also OLIVE 1981 . For a review of limits based on Nucleosynthesis, Supernovae, and also on terrestial experiments, see DENEGRI 1990 . Also see ``Big-Bang Nucleosynthesis'' in this $\mathit Review$.
VALUE CL% DOCUMENT ID TECN  COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •
$\text{2.3 - 3.2}$ 95 1
VERDE
2017
COSM
$2.88$ $\pm0.20$ 95 2
ROSSI
2015
COSM
$3.3$ $\pm0.5$ 95 3
ADE
2014
COSM Planck
$3.78$ ${}^{+0.31}_{-0.30}$ 4
COSTANZI
2014
COSM
$3.29$ $\pm0.31$ 5
HOU
2014
COSM
$<3.80$ 95 6
LEISTEDT
2014
COSM
$<4.10$ 95 7
MORESCO
2012
COSM
$<5.79$ 95 8
XIA
2012
COSM
$<4.08$ 95
MANGANO
2011
COSM BBN
$\text{0.9 - 8.2}$ 9
ICHIKAWA
2007
COSM
$\text{3 - 7}$ 95 10
CIRELLI
2006
COSM
$\text{2.7 - 4.6}$ 95 11
HANNESTAD
2006
COSM
$\text{3.6 - 7.4}$ 95 10
SELJAK
2006
COSM
$<4.4$ 12
CYBURT
2005
COSM
$<3.3$ 13
BARGER
2003C
COSM
$\text{1.4 - 6.8}$ 14
CROTTY
2003
COSM
$\text{1.9 - 6.6}$ 14
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
$<16$ 15
SHVARTSMAN
1969
Cosmology
HOYLE
1964
Cosmology
1  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.
2  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.
3  Fit to the number of neutrino degrees of freedom from Planck CMB data along with WMAP polarization, high L, and BAO data.
4  Fit to the number of neutrinos degrees of freedom from Planck CMB data along with BAO, shear and cluster data.
5  Fit based on the SPT-SZ survey combined with CMB, BAO, and ${{\mathit H}_{{0}}}$ data.
6  Constrains the number of neutrino degrees of freedom (marginalizing over the total mass) from CMB, CMB lensing, BAO, and galaxy clustering data.
7  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 $3.45$ $\pm0.65$.
8  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.
9  Constrains the number of neutrino types from recent CMB and large scale structure data. No priors on other cosmological parameters are used.
10  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.
11  Constrains the number of neutrino types from recent CMB and large scale structure data. See also HAMANN 2007 .
12  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 .
13  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{}$3 is assumed to compute the limit.
14  95$\%$ confidence level range on the number of neutrino flavors from WMAP data combined with other CMB measurements, the 2dfGRS data, and HST data.
15  SHVARTSMAN 1969 limit inferred from his equations.
  References:
VERDE 2017
JCAP 1704 023 Early Cosmology Constrained
ROSSI 2015
PR D92 063505 Constraints on Dark Radiation from Cosmological Probes
ADE 2014
AA 571 A16 Planck 2013 Results. XVI. Cosmological Parameters
COSTANZI 2014
JCAP 1410 081 Neutrino Constraints: what Large-Scale Structure and CMB Data are Telling Us?
HOU 2014
APJ 782 74 Constraints on Cosmology from the Cosmic Microwave Background Power Spectrum of the 2500 deg${}^{2}$ SPT-SZ Survey
LEISTEDT 2014
PRL 113 041301 No New Cosmological Concordance with Massive Sterile Neutrinos
MORESCO 2012
JCAP 1207 053 New Constraints on Cosmological Parameters and Neutrino Properties using the Expansion Rate of the Universe to z ~ 1.75
XIA 2012
JCAP 1206 010 Constraints on Massive Neutrinos from the CFHTLS Angular Power Spectrum
MANGANO 2011
PL B701 296 A Robust Upper Limit on ${{\mathit N}_{{eff}}}$ from BBN, circa 2011
ICHIKAWA 2007
JCAP 0705 007 Constraint on the Effective Number of Neutrino Species from the WMAP and SDSS LRG Power Spectra
CIRELLI 2006
JCAP 0612 013 Cosmology of Neutrinos and Extra-Light Particles after WMAP3
HANNESTAD 2006
JCAP 0611 016 Neutrino Masses and Cosmic Radiation Density: Combined Analysis
SELJAK 2006
JCAP 0610 014 Cosmological Parameters from Combining the Lyman-$\alpha $ Forest with CMB, Galaxy Clustering and SN Constraints
CYBURT 2005
ASP 23 313 New BBN Limits on Physics Beyond the Standard Model from ${}^{4}\mathrm {He}$
BARGER 2003C
PL B566 8 Effective Number of Neutrinos and Baryon Asymmetry from BBN and WMAP
CROTTY 2003
PR D67 123005 Measuring the Cosmological Background of Relativistic Particles with the Wilkinson Microwave Anisotropy Probe
PIERPAOLI 2003
MNRAS 342 L63 Constraints on the Cosmic Neutrino Background
LISI 1999
PR D59 123520 The Big Bang Nucleosynthesis Limit on N$_{{{\mathit \nu}}}$
OLIVE 1999
ASP 11 403 Generalized Limits to the Number of Light Particle Degrees of Freedom from Big Bang Nucleosynthesis
COPI 1997
PR D55 3389 The Big Bang Nucleosynthesis Limit to the Number of Neutrino Species
HATA 1997B
PR D55 540 Cosmological Implications of Two Conflicting Deuterium Abundances
OLIVE 1997
ASP 7 27 A Big Bang Nucleosynthesis Likelihood Analysis of the Baryon to Photon Ratio and the Number of Light Particle Degrees of Freedom
CARDALL 1996B
APJ 472 435 Big Bang Nucleosynthesis in Light of Discordant Deuterium Measurements
FIELDS 1996
New Ast 1 77 Model Independent Predictions of Big Bang Nucleosinthesis from ${}^{4}\mathrm {He}$ and ${}^{7}\mathrm {Li}$: Consistency and Implications
KERNAN 1996
PR D54 3681 No Crisis for Big Bang Nucleosynthesis
OLIVE 1995
PL B354 357 A New Look at Neutrino Limits from Big Bang Nucleosynthesis
WALKER 1991
APJ 376 51 Primordial Nucleosynthesis Redux
OLIVE 1990
PL B236 454 Big Bang Nucleosynthesis Revisited
YANG 1984
APJ 281 493 Primordial Nucleosynthesis: a Critical Comparison of Theory and Observation
YANG 1979
APJ 227 697 Constraints on Cosmology and Neutrino Physics from Big Bang Nucleosynthesis
STEIGMAN 1977
PL 66B 202 Cosmological Limits to the Number of Massive Leptons
PEEBLES 1971
Physical Cosmology Physical Cosmology (Princeton, 1971) Book. (294p.)
SHVARTSMAN 1969
JETPL 9 184 Density of Relict Particles with Zero Rest Mass in the Universe
HOYLE 1964
NAT 203 1108 The Mystery of the Cosmic Helium Abundance
HAMANN 2007
JCAP 0708 021 Observational Bounds on the Cosmic Radiation Density
KNELLER 2001
PR D64 123506 How Does CMB + BBN Constrain New Physics?
CYBURT 2001
ASP 17 87 Primordial Nucleosynthesis with CMB Inputs: Probing the Early Universe and Light Element Astrophysics
CYBURT 2003
PL B567 227 Primordial Nucleosynthesis in Light of WMAP
DENEGRI 1990
RMP 62 1 The Number of Neutrino Species
OLIVE 1981
APJ 246 557 Big Bang Nucleosynthesis as a Probe of Cosmology and Particle Physics