Transcript E. Di Valentino et al., Phys. Rev. D90 (2014), 043534
Constraining Fundamental Physics with current Cosmologica Data
PhD Candidate: Eleonora Di Valentino Supervisor: Prof. Alessandro Melchiorri
Università 'La Sapienza' di Roma Dottorato in fisica, XXVI ciclo
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Publications
E. Di Valentino , A. Melchiorri, L. Pagano, "Testing the inflationary null energy condition with current and future cosmic microwave background data", Int.J.Mod.Phys. D20 (2011), 1183-1189, E. Di Valentino , M. Lattanzi, G. Mangano, A. Melchiorri, P. D. Serpico, "Future constraints on neutrino isocurvature perturbations in the Curvaton scenario", Phys. Rev. D85 (2012), 043511; E. Di Valentino , A. Melchiorri, V. Salvatelli, A. Silvestri, "Parametrised modified gravity and the CMB Bispectrum", Phys. Rev. D86 (2012), 063517.
E. Di Valentino , M. Gerbino, A. Melchiorri, "Dark radiation and the CMB bispectrum", Phys. Rev. D87 (2013) 10, 103523.
● ● ● ● ● ● E. Di Valentino , S. Galli, M. Lattanzi, A. Melchiorri, P. Natoli, L. Pagano, N. Said, "Tickling the CMB damping tail: scrutinizing the tension between the ACT and SPT experiments", Phys. Rev. D88 (2013) 2, 023501 (2013); N. Said, E. Di Valentino , M. Gerbino, "Planck constraints on the effective neutrino number and the CMB power spectrum lensing amplitude", Phys. Rev. D88 (2013) 2, 023513; M. Gerbino, E. Di Valentino , N. Said, "Neutrino anisotropies after Planck", Phys. Rev. D88 (2013) 6, 063538.
E. Di Valentino , A. Melchiorri, O. Mena, "Dark radiation sterile neutrino candidates after Planck data", JCAP 1311 (2013) 018.
E. Giusarma, E. Di Valentino , M. Lattanzi, A. Melchiorri, O. Mena, "Relic Neutrinos, thermal axions and cosmology in early 2014", Phys. Rev. D90 (2014), 043507.
M. Gerbino, A. Marchini, L. Pagano, L. Salvati, E. Di Valentino , A. Melchiorri, "Blue Gravity Waves from BICEP2 ?", Phys. Rev. D90 (2014), 047301.
● ● ● E. Di Valentino , E. Giusarma, M. Lattanzi, A. Melchiorri, O. Mena, "Axion cold dark matter: status after Planck and BICEP2", Phys. Rev. D90 (2014), 043534.
E. Di Valentino Planck and BICEP2", Phys. Rev. D90 (2014), 023543.
E. Di Valentino , A. Melchiorri, "Planck constraints on neutrino isocurvature density perturbations", arXiv:1405.5418v1 (in press).
● ● ● ●
Publications
E. Di Valentino, A. Melchiorri, L. Pagano, "Testing the inflationary null energy condition with current and future cosmic microwave background data", Int.J.Mod.Phys. D20 (2011), 1183-1189, E. Di Valentino, M. Lattanzi, G. Mangano, A. Melchiorri, P. D. Serpico, "Future constraints on neutrino isocurvature perturbations in the Curvaton scenario", Phys. Rev. D85 (2012), 043511; E. Di Valentino, A. Melchiorri, V. Salvatelli, A. Silvestri, "Parametrised modified gravity and the CMB Bispectrum", Phys. Rev. D86 (2012), 063517.
E. Di Valentino, M. Gerbino, A. Melchiorri, "Dark radiation and the CMB bispectrum", Phys. Rev. D87 (2013) 10, 103523.
● ● ● ● ● ● E. Di Valentino, S. Galli, M. Lattanzi, A. Melchiorri, P. Natoli, L. Pagano, N. Said, "Tickling the CMB damping tail: scrutinizing the tension between the ACT and SPT experiments", Phys. Rev. D88 (2013) 2, 023501 (2013); N. Said, E. Di Valentino, M. Gerbino, "Planck constraints on the effective neutrino number and the CMB power spectrum lensing amplitude", Phys. Rev. D88 (2013) 2, 023513; M. Gerbino, E. Di Valentino, N. Said, "Neutrino anisotropies after Planck", Phys. Rev. D88 (2013) 6, 063538.
E. Di Valentino, A. Melchiorri, O. Mena, "Dark radiation sterile neutrino candidates after Planck data", JCAP 1311 (2013) 018.
E. Giusarma, E. Di Valentino, M. Lattanzi, A. Melchiorri, O. Mena, "Relic Neutrinos, thermal axions and cosmology in early 2014", Phys. Rev. D90 (2014), 043507.
M. Gerbino, A. Marchini, L. Pagano, L. Salvati, E. Di Valentino, A. Melchiorri, "Blue Gravity Waves from BICEP2 ?", Phys. Rev. D90 (2014), 047301.
● ● ● E. Di Valentino, E. Giusarma, M. Lattanzi, A. Melchiorri, O. Mena, "Axion cold dark matter: status after Planck and BICEP2", Phys. Rev. D90 (2014), 043534.
Planck and BICEP2", Phys. Rev. D90 (2014), 023543.
E. Di Valentino, A. Melchiorri, "Planck constraints on neutrino isocurvature density perturbations", arXiv:1405.5418v1 (in press).
Outline:
●
Introduction to cosmology
●
The neutrino effective number N
eff ●
Axion cosmology
●
The rate A
2
of the radiative capture reaction
d(p;γ)
3
He
●
Conclusions
Introduction to cosmology
The Universe originates from a hot Big Bang. The primordial plasma in thermodynamic equilibrium cools with the expansion of the Universe. It passes through the phase of decoupling, in which the Universe becomes trasparent to the motion of photons, and the phase of recombination, where electrons and protons combine into hydrogen atoms. The Cosmic Microwave Background (CMB) is the radiation coming from the recombination, emitted about 13 billion years ago, just 400,000 years after the Big Bang. The CMB provides an unexcelled probe of the early Universe and today it is a black body a temperature T=2.726K.
Introduction to cosmology
Ade et al., arXiv:1303.5076
The main tool of research in cosmology is the angular power spectrum of CMB temperature anisotropies.
T T
T T
1 2 ( 2 1 )
C
P
1 2
Introduction to cosmology
Theoretical model Cosmological parameters: (Ω b h 2 , Ω m h 2 , h , n s , τ, Σm ν ) DATA
PARAMETER CONSTRAINTS
The Cosmic Neutrino Background
When the rate of the weak interaction reactions, which keep neutrinos in equilibrium with the primordial plasma, becomes smaller than the expansion rate of the Universe, neutrinos decouple at a temperature of about:
T dec
1
MeV
After neutrinos decoupling, photons are heated by electrons-positrons annihilation. When also photons decouple, the ratio between the temperatures of photons and neutrinos will be fixed, despite the temperature decreases with the expansion of the Universe. We expect today a Cosmic Neutrino Background (CNB) at a temperature:
T
4 11 1 / 3
T
1 .
945
K
kT
1 .
68 10 4
eV
With a number density of:
N
eff
The relativistic neutrinos contribute to the present energy density of the Universe: We can introduce the effective number of relativistic degrees of freedom: The expected value is N eff = 3.046
oscillations.
, if we assume standard electroweak interactions and three active massless neutrinos. The (Mangano et al. 2005) 0.046
takes into account effects for the non-instantaneous neutrino decoupling and neutrino flavour
N
eff Measuring
Δ
N
eff
≡ N
eff
− 3.046
we can constrain the dark radiation.
Increasing N eff essentially increases the expansion rate H: So decrease the sound horizon at recombination, and the diffusion distance (damping scale): CMB acoustic peaks shifted and smeared
The Planck satellite detected with higher precision the anisotropy damping tail, allowing to better constrain the parameters of new physics that affect it.
(E. Calabrese et al. 2008) AL =0,1,3,6,9
The lensing amplitude
The lensing amplitude A L parameterizes the rescaling of the lensing potential ( then the power spectrum of the lensing field:
n
), The gravitational lensing deflects the photon path by a quantity defined by the gradient of the lensing potential (
n
), integrated along the line of sight
n
, remapping the temperature field. Its effect on the power spectrum is the smoothing of the acoustic peaks, increasing A L . If A L =1 then the theory is correct, else we have a new physics/systematics?
(E. Calabrese et al. 2008)
A L
0 , 1 , 3 , 6 , 9
Pre-Planck constraints
Both N
eff
and A
L
affect the damping tail. Before the release of the Planck data, ACT and SPT were in tension on constraining them.
E. Di Valentino et al, Phys. Rev D, 88, 023501, 2013
What about
Planck
?
Planck+WP 2013 result does not solve the issue!
N
eff
from Planck is in better agreement with SPT !
A
L
from Planck is in better agreement with ACT !
(68%; Planck+WP) N. Said, E. Di Valentino, M. Gerbino, Phys. Rev D, 88, 023513, 2013
E. Di Valentino et al, Phys. Rev D, 88, 023501, 2013 N. Said, E. Di Valentino, M. Gerbino, Phys. Rev D, 88, 023513, 2013
The most elegant and promising solution of the so-called
strong CP problem
in Quantum Chromodynamics (QCD) was provided by Peccei and Quinn, adding a new global U(1) PQ symmetry. This is spontaneously broken at an energy scale f a , generating a new spinless particle, the axion. The axion can be copiously produced in the universe's early stages, both via thermal and non thermal processes.
● ● Thermal axions with sub-eV masses contribute to the hot dark matter component of the universe, as neutrinos, and we have updated the cosmological limits on their properties in E. Giusarma, E. Di Valentino, M. Lattanzi, A. Melchiorri and O. Mena, Phys. Rev. D90 (2014), 043507.
Axion-like particles produced non-thermally, instead were postulated as natural candidates for the cold dark matter component, and we put this "axion dark matter" (ADM) scenario under scrutiny using the most recent cosmological data in E. Di Valentino, E. Giusarma, M. Lattanzi, A. Melchiorri and O. Mena, Phys. Rev. D90 (2014), 043534.
Thermal axions with sub-eV masses contribute to the hot dark matter component of the universe, so to the extra radiation component at the BBN period, by an amount given by: E. Giusarma, E. Di Valentino, M. Lattanzi, A. Melchiorri and O. Mena, Phys. Rev. D90 (2014), 043507
E. Giusarma, E. Di Valentino, M. Lattanzi, A. Melchiorri and O. Mena, Phys. Rev. D90 (2014), 043507
For these datasets there is an evidence at more than 2σ for an axion mass of 0.6eV
E. Giusarma, E. Di Valentino, M. Lattanzi, A. Melchiorri and O. Mena, Phys. Rev. D90 (2014), 043507
For these datasets there is an evidence at more than 3σ for a neutrino mass of 0.2eV
No evidence for neutrino and axion masses simultaneously!
E. Giusarma, E. Di Valentino, M. Lattanzi, A. Melchiorri and O. Mena, Phys. Rev. D90 (2014), 043507
For temperatures between the energy scale f a and the QCD phase transition Λ QCD , the axion is a massless particle, then the axion acquires a mass via instanton effects. The effective potential V for the axion field a(x) is generated through non-pertubative QCD effects, and may be written as Introducing the misalignment angle θ = a/f a , the field evolves according to the Klein-Gordon equation on a flat Friedmann-Robertson-Walker background: with
The PQ symmetry breaking can occur before or after inflation: ● If the PQ symmetry is broken after inflation, there are no axion isocurvature perturbations since there are not axion quantum fluctuations, but there will exist a contribution to the total axion energy density from axionic string decays; ● If there was an inflationary period in the universe after or during the PQ phase transition, there will exist, together with the standard adiabatic perturbations generated by the inflaton field, axion isocurvature perturbations, associated to quantum fluctuations in the axion field, and the initial misalignment angle should be identical in the whole observable universe.
The PQ symmetry breaking can occur before or after inflation: ● If the PQ symmetry is broken after inflation, there are no axion isocurvature perturbations since there are not axion quantum fluctuations, but there will exist a contribution to the total axion energy density from axionic string decays.
If the axion created non-thermally in the early Universe through the misalignment mechanism and the decay of axionic strings, we can constrain the "axion dark matter" scenario in which the PQ symmetry is broken after inflation, using the most precise CMB data available to date.
We consider the hypothesis that the axion accounts for all the CDM present in the Universe, i.e Ω CDM = Ω a,mis .
Considering also extended scenario we obtain an axion with mass in the range 70-80 μeV.
E. Di Valentino, E. Giusarma, M. Lattanzi, A. Melchiorri, O. Mena, Phys. Rev. D90 (2014), 043534
● ● ● The search for axion dark matter is also the target of laboratory experiments like the Axion Dark Matter eXperiment (ADMX) operating in the range 0.3 - 1 GHz, thus being axions in the mass range between 1.9 and 3.53 μeV . , that uses a tunable microwave cavity positioned in a high magnetic field to detect the conversion of axions into photons. ADMX has been able to exclude DM To reach the typical masses found in our study , this should be enhanced at a resonant frequency of 20 GHz , if the PQ symmetry is broken after inflation. A smaller experiment called ADMX-HF is currently being built, that will allow to probe the 4 - 40 Ghz range, thus being in principle sensitive to axion masses in the 100 μeV range , allowing to directly test the ADM scenario.
BBN
Big Bang Nucleosynthesis (BBN) offers one of the most powerful methods to test the validity of the cosmological model around the MeV energy scale. BBN relates key cosmological parameters: ● the energy density in baryons, Ω b h 2 ● the effective neutrino number, N eff to the primordial abundance of light elements.
Deuterium abundance
Big Bang Nucleosynthesis (BBN) offers one of the most powerful methods to test the validity of the cosmological model around the MeV energy scale. The deuterium primordial abundance 2 H/H is: ● a rapidly decreasing function of Ω b h 2 ● a growing function of N eff
Deuterium abundance
Assuming the standard cosmological model, we show in E. Di Valentino et al., Phys. Rev. D90 (2014), 023543 , that combining ● ● the Planck data the recent deuterium abundance measurements in metal-poor damped Lyman-alpha systems we have independent information on the cross section of the radiative capture reaction
d(p;γ) 3 He
converting deuterium into helium.
Deuterium abundance
Assuming a given cosmological scenario and standard BBN dynamics, it's possible to infer indirectly from Planck data the abundance of primordial nuclides with exquisite precision. From the Planck constraint on the baryon density: using the public BBN code PArthENoPE we have:
Cosmological determination
Deuterium abundance
A new analysis R. Cooke et al. (2013) of all known deuterium absorption-line systems, including some new data from very metal poor Lyman-alpha systems at redshift z = 3.06726 (visible in the spectrum of the quasar QSO SDSS J1358+6522) and at redshift z = 3.04984 (seen in QSO SDSS J1419+0829), gives:
Astrophysical determination
Planck
Lyman-alpha
Deuterium abundance
Planck
Lyman-alpha
Deuterium abundance
These two deuterium abundance determinations, while broadly consistent, are off by about two standard deviations.
This small tension might well be the result of small experimental systematics in these measurements....
...or the current BBN calculations could also be plagued by systematics in the experimental determination of nuclear rates.
d(p;γ)
3
He
The main uncertainty for standard BBN calculations of 2 H comes from the rate R 2 of the radiative capture reaction
d(p;γ) 3 He ,
measured from nuclear experimental data.
A reliable
ab initio
nuclear theory calculation of this cross section is systematically larger energy range than the best-fit value derived from the experimental data in the BBN
[30-300 keV]
. Further data on R 2 in the relevant energy range might be expected from experiments such as LUNA.
d(p;γ)
3
He
If we put the theoretical estimate of R 2 in a BBN code value of the cosmological baryon density. In this way, , we find that more deuterium is destroyed for the same the predicted primordial 2 H abundance by Planck results to be smaller, i.e. more in agreement with the astrophysical estimate.
Could be this a way to reconcile the different values of
2
H/H measured in astrophysical and cosmological data?
d(p;γ)
3
He
We analyzed the Planck data considering the rate of the radiative capture reaction
d(p;γ) 3 He
as a free input parameter .
Actually the present CMB data are powerful enough to provide information on nuclear rates.
Our aim is to find which value of this cross section, brings the Planck predictions in better agreement with the deuterium measurements. We find that our results give independent support to the theoretical calculation: the rate of the radiative capture reaction
d(p;γ) 3 He
is larger than measured from the nuclear experiments.
We parametrize the generic R 2 (T) in terms of an overall rescaling factor A 2
A
2 We find that the data provide an indication for A 2 being greater than one, at about 2σ .
E. Di Valentino et al., Phys. Rev. D90 (2014), 023543
Conclusions:
The goal of my PhD thesis was to constrain fundamental physics using current cosmological data, in order to identify possible hints for new physics studiyng the tensions between the several experiments.
Current cosmological data are suggesting both a Neutrino Effective Number and a Lensing Amplitude greater than the standard value, N experiments. eff >3.046 and A L >1. Obviously, these results could be due to a possible new physics or a systematics in the different A possible candidate for this extra dark radiation Δ N eff ≡ N eff − 3.046 is the thermal axion with a mass m μeV.
a <1eV at 95% c.l.. We investigated also the possibility of an axion particle that account for all the cold dark matter in the universe, finding a mass in the range 70-80 Finally, we have investigated the tension between the baryon density Ω that a higher rate is favoured from the Planck data.
b h 2 measured from Planck satellite and metal-poor Lyman-alpha systems, traslated into a different estimate of the primordial deuterium abundance. We considered the possibility of systematics in current experimental data for the rate of the radiative capture process d(p,y) 3 He, because theoretical calculations predict a rate about 5-10% higher than what has been measured. Parameterizing this reaction and modifying the PArthENoPE code accordingly, we found
We expect that the next Planck data release (in which I'm involved), in December 2014, will help in solving/confirming these issues.
References
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P. A. R. Ade et al. [ Planck Collaboration], arXiv: 1303.5076 [astroph.CO]; P. A. R. Ade et al. [Planck Collaboration], arXiv:1303.5080 [astroph.CO]; J. Lesgourgues and S. Pastor, arXiv:1212.6154 [hepph]; G. Mangano et al., Nucl. Phys. B 729, 221 (2005) [hepph/0506164]; Calabrese et al., Phys. Rev. D, 77, 123531; Sievers et al., arXiv: 1301.0824; Story et al., arXiv: 1210.7231; Hou et al., arXiv:1212.6267v1; E. Di Valentino et al., Phys. Rev. D88 (2013) 2, 023501 (2013); N. Said et al., Phys. Rev. D88 (2013) 2, 023513; R. D. Peccei and H. R. Quinn, Phys. Rev. Lett. 38, 1440 (1977); E. Giusarma et al., Phys. Rev. D90 (2014), 043507; L. Visinelli and P. Gondolo, arXiv:1403.4594 [hepph]; D.J. Gross, R.D. Pisarski, and L.G. Yaffe, Rev. Mod. Phys. 53, 43 (1981); L. Visinelli and P. Gondolo, Phys. Rev. D 80, 035024 (2009); E. Di Valentino et al., Phys. Rev. D90 (2014), 043534; R. Cooke et al., arXiv:1308.3240 [astroph.CO]; L. E. Marcucci et al., Phys. Rev. C 72, 014001 (2005); K. M. Nollett and G. P. Holder, arXiv:1112.2683 [astroph.CO]; O. Pisanti et al.,arXiv:0705.0290 [astroph]], URL http://parthenope.na.infn.it/; E. Di Valentino et al., Phys. Rev. D90 (2014), 023543.
CMB data: ● CMB temperature anisotropies measured by the Planck satellite (including information on the lensing potential) ● ● 9-year polarization data from WMAP additional temperature data from high-resolution CMB experiments, ACT and SPT .
Large scale structure data: All the available galaxy survey measurements in the form of Baryon Acoustic Oscillation (BAO) data: ➔ ➔ SDSS Data Release 7 WiggleZ survey ➔ ➔ 6dF BOSS Data Release 11 (DR11) The full matter power spectrum form in order to quantify the benefits of using shape measurements of the matter power spectrum versus geometrical BAO information: ➔ WiggleZ survey (WZ)
Additional datasets: ● Supernova luminosity distance SNLS ● Hubble costant measurements HST σ 8 -Ω m measurements: ● CFHTLens survey, through the amplitude and the shape of the weak lensing signal ● The Planck Sunyaev-Zeldovich ( SZ ) selected clusters catalog, from the abundance of clusters as a function of the redshift