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Author |
Simpson, F.; Jimenez, R.; Pena-Garay, C.; Verde, L. |
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Title |
Dark energy from the motions of neutrinos |
Type |
Journal Article |
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Year |
2018 |
Publication |
Physics of the Dark Universe |
Abbreviated Journal |
Phys. Dark Universe |
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Volume |
20 |
Issue |
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Pages |
72-77 |
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Keywords |
Neutrinos; Dark energy; Interactions in the dark sector |
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Abstract |
Ordinarily, a scalar field may only play the role of dark energy if it possesses a potential that is either extraordinarily flat or extremely fine-tuned. Here we demonstrate that these restrictions are lifted when the scalar field undergoes persistent energy exchange with another fluid. In this scenario, the field is prevented from reversing its direction of motion, and instead may come to rest while displaced from the local minimum of its potential. Therefore almost any scalar potential is capable of initiating a prolonged phase of cosmic acceleration. If the rate of energy transfer is modulated via a derivative coupling, the field undergoes a rapid process of freezing, after which the field's equation of state mimicks that of a cosmological constant. We present a physically motivated realisation in the form of a neutrino-majoron coupling, which avoids the dynamical instabilities associated with mass-varying neutrino models. Finally we discuss possible means by which this model could be experimentally verified. |
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Address |
[Simpson, Fergus; Jimenez, Raul; Verde, Licia] Univ Barcelona, UB IEEC, ICC, Marti i Franques 1, E-08028 Barcelona 08028, Spain, Email: feigus2@icc.ub.edu; |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Language |
English |
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ISSN |
2212-6864 |
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Notes |
WOS:000433904300009 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial  |
3599 |
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Author |
Beltran Jimenez, J.; Heisenberg, L.; Olmo, G.J. |
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Title |
Tensor perturbations in a general class of Palatini theories |
Type |
Journal Article |
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Year |
2015 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
06 |
Issue |
6 |
Pages |
026 - 16pp |
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Keywords |
modified gravity; inflation; gravity; dark energy theory |
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Abstract |
We study a general class of gravitational theories formulated in the Palatini approach and derive the equations governing the evolution of tensor perturbations. In the absence of torsion, the connection can be solved as the Christoffel symbols of an auxiliary metric which is non-trivially related to the space-time metric. We then consider background solutions corresponding to a perfect fluid and show that the tensor perturbations equations (including anisotropic stresses) for the auxiliary metric around such a background take an Einstein-like form. This facilitates the study in a homogeneous and isotropic cosmological scenario where we explicitly establish the relation between the auxiliary metric and the spacetime metric tensor perturbations. As a general result, we show that both tensor perturbations coincide in the absence of anisotropic stresses. |
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Address |
[Jimenez, Jose Beltran] Univ Louvain, Inst Math & Phys, Ctr Cosmol Particle Phys & Phenomenol, B-1318 Louvain, Belgium, Email: jose.beltran@cpt.univ.mrs.fr; |
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Publisher |
Iop Publishing Ltd |
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English |
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Series Volume |
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Edition |
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ISSN |
1475-7516 |
ISBN |
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Notes |
WOS:000359215400027 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2368 |
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Author |
Anderson, L. et al; Mena, O. |
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Title |
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: baryon acoustic oscillations in the Data Releases 10 and 11 Galaxy samples |
Type |
Journal Article |
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Year |
2014 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
Mon. Not. Roy. Astron. Soc. |
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Volume |
441 |
Issue |
1 |
Pages |
24-62 |
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Keywords |
cosmological parameters; cosmology: observations; dark energy; distance scale; large-scale structure of Universe |
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Abstract |
We present a one per cent measurement of the cosmic distance scale from the detections of the baryon acoustic oscillations (BAO) in the clustering of galaxies from the Baryon Oscillation Spectroscopic Survey, which is part of the Sloan Digital Sky Survey III. Our results come from the Data Release 11 (DR11) sample, containing nearly one million galaxies and covering approximately 8500 square degrees and the redshift range 0.2 < z < 0.7. We also compare these results with those from the publicly released DR9 and DR10 samples. Assuming a concordance A cold dark matter (ACDM) cosmological model, the DR11 sample covers a volume of 13 Gpc(3) and is the largest region of the Universe ever surveyed at this density. We measure the correlation function and power spectrum, including density- field reconstruction of the BAO feature. The acoustic features are detected at a significance of over 7s in both the correlation function and power spectrum. Fitting for the position of the acoustic features measures the distance relative to the sound horizon at the drag epoch, r(d), which has a value of r(d,fid) = 149.28 Mpc in our fiducial cosmology. We find D-V = (1264 +/- 25 Mpc)(r(d)/r(d,fid)) at z = 0.32 and D-V = (2056 +/- 20 Mpc)(r(d)/r(d,fid)) at z = 0.57. At 1.0 per cent, this latter measure is the most precise distance constraint ever obtained from a galaxy survey. Separating the clustering along and transverse to the line of sight yields measurements at z = 0.57 of D-A = (1421 +/- 20 Mpc)(r(d)/r(d,fid)) and H = (96.8 +/- 3.4 kms(-1) Mpc(-1))(r(d),(fid)/r(d)). Our measurements of the distance scale are in good agreement with previous BAO measurements and with the predictions from cosmic microwave background data for a spatially flat CDM model with a cosmological constant. |
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Address |
[Anderson, Lauren; Bhardwaj, Vaishali] Univ Washington, Dept Astron, Seattle, WA 98195 USA, Email: djschlegel@lbl.gov; |
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Publisher |
Oxford Univ Press |
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English |
Summary Language |
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ISSN |
0035-8711 |
ISBN |
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Notes |
WOS:000336249300002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1791 |
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Author |
Anderson, L. et al; Mena, O. |
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Title |
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: measuring D-A and H at z=0.57 from the baryon acoustic peak in the Data Release 9 spectroscopic Galaxy sample |
Type |
Journal Article |
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Year |
2014 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
Mon. Not. Roy. Astron. Soc. |
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Volume |
439 |
Issue |
1 |
Pages |
83-101 |
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Keywords |
cosmological parameters; cosmology: observations; dark energy; distance scale; large scale structure of Universe |
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Abstract |
We present measurements of the angular diameter distance to and Hubble parameter at z = 0.57 from the measurement of the baryon acoustic peak in the correlation of galaxies from the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey. Our analysis is based on a sample from Data Release 9 of 264 283 galaxies over 3275 square degrees in the redshift range 0.43 < z < 0.70. We use two different methods to provide robust measurement of the acoustic peak position across and along the line of sight in order to measure the cosmological distance scale. We find D-A(0.57) = 1408 +/- 45 Mpc and H(0.57) = 92.9 +/- 7.8 km s(-1) Mpc(-1) for our fiducial value of the sound horizon. These results from the anisotropic fitting are fully consistent with the analysis of the spherically averaged acoustic peak position presented in Anderson et al. Our distance measurements are a close match to the predictions of the standard cosmological model featuring a cosmological constant and zero spatial curvature. |
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Address |
[Anderson, Lauren] Univ Washington, Dept Astron, Seattle, WA 98195 USA, Email: djschlegel@lbl.gov |
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Publisher |
Oxford Univ Press |
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English |
Summary Language |
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ISSN |
0035-8711 |
ISBN |
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Expedition |
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Conference |
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Notes |
WOS:000333297700026 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1738 |
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Author |
Di Valentino, E.; Melchiorri, A.; Mena, O. |
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Title |
Dark radiation sterile neutrino candidates after Planck data |
Type |
Journal Article |
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Year |
2013 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
11 |
Issue |
11 |
Pages |
018 - 13pp |
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Keywords |
cosmological neutrinos; neutrino properties; neutrino theory; dark energy theory |
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Abstract |
Recent Cosmic Microwave Background (CMB) results from the Planck satellite, combined with previous CMB data and Hubble constant measurements from the Hubble Space Telescope, provide a constraint on the effective number of relativistic degrees of freedom 3.62(-0.48)(+0.50) at 95% CL. New Planck data provide a unique opportunity to place limits on models containing relativistic species at the decoupling epoch. We present here the bounds on sterile neutrino models combining Planck data with galaxy clustering information. Assuming N-eff active plus sterile massive neutrino species, in the case of a Planck+WP+HighL+HST analysis we find m(nu,sterile)(eff) < 0.36 eV and 3.14 < N-eff < 4.15 at 95% CL, while using Planck+WP+HighL data in combination with the full shape of the galaxy power spectrum from the Baryon Oscillation Spectroscopic Survey BOSS Data Relase 9 measurements, we find that 3.30 < N-eff < 4.43 and m(nu,sterile)(eff) < 0.33 eV both at 95% CL with the three active neutrinos having the minimum mass allowed in the normal hierarchy scheme, i.e. Sigma m(nu) similar to 0.06 eV. These values compromise the viability of the (3 + 2) massive sterile neutrino models for the parameter region indicated by global fits of neutrino oscillation data. Within the (3 + 1) massive sterile neutrino scenario, we find m(nu,sterile)(eff) < 0.34 eV at 95% CL. While the existence of one extra sterile massive neutrino state is compatible with current oscillation data, the values for the sterile neutrino mass preferred by oscillation analyses are significantly higher than the current cosmological bound. We review as well the bounds on extended dark sectors with additional light species based on the latest Planck CMB observations. |
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Address |
[Di Valentino, Eleonora; Melchiorri, Alessandro] Univ Roma La Sapienza, Dept Phys, I-00185 Rome, Italy, Email: eleonora.divalentino@roma1.infn.it; |
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Corporate Author |
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Thesis |
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Publisher |
Iop Publishing Ltd |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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ISSN |
1475-7516 |
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Conference |
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Notes |
WOS:000327843900019 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1672 |
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