Records |
Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Barenboim, G.; Fernandez-Martinez, E.; Mena, O.; Verde, L. |
Title |
The dark side of curvature |
Type |
Journal Article |
Year |
2010 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
Volume |
03 |
Issue |
3 |
Pages |
008 - 17pp |
Keywords |
dark energy experiments; baryon acoustic oscillations; cosmological parameters from CMBR |
Abstract |
Geometrical tests such as the combination of the Hubble parameter H(z) and the angular diameter distance d(A)(z) can, in principle, break the degeneracy between the dark energy equation of state parameter w(z), and the spatial curvature Omega(k) in a direct, model-independent way. In practice, constraints on these quantities achievable from realistic experiments, such as those to be provided by Baryon Acoustic Oscillation (BAO) galaxy surveys in combination with CMB data, can resolve the cosmic confusion between the dark energy equation of state parameter and curvature only statistically and within a parameterized model for w(z). Combining measurements of both H(z) and d(A)(z) up to sufficiently high redshifts z similar to 2 and employing a parameterization of the redshift evolution of the dark energy equation of state are the keys to resolve the w(z) – Omega(k) degeneracy. |
Address |
[Barenboim, Gabriela] Univ Valencia, Dept Fis Teor, E-46100 Valencia, Spain, Email: Gabriela.Barenboim@uv.es |
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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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1475-7516 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
ISI:000276103000026 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
no |
Call Number |
IFIC @ elepoucu @ |
Serial |
465 |
Permanent link to this record |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Archidiacono, M.; Lopez-Honorez, L.; Mena, O. |
Title |
Current constraints on early and stressed dark energy models and future 21 cm perspectives |
Type |
Journal Article |
Year |
2014 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
Volume |
90 |
Issue |
12 |
Pages |
123016 - 10pp |
Keywords |
|
Abstract |
Despite the great progress of current cosmological measurements, the nature of the dominant component of the Universe, coined dark energy, is still an open question. Early dark energy is a possible candidate which may also alleviate some fine-tuning issues of the standard paradigm. Using the latest available cosmological data, we find that the 95% C.L. upper bound on the early dark energy density parameter is Tau(eDE) < 0.009. On the other hand, the dark energy component may be a stressed and inhomogeneous fluid. If this is the case, the effective sound speed and the viscosity parameters are unconstrained by current data. Future omniscopelike 21 cm surveys, combined with present cosmic microwave background data, could be able to distinguish between standard quintessence scenarios from other possible models with 2 sigma significance, assuming a non-negligible early dark energy contribution. The precision achieved on the Omega(eDE) parameter from these 21 cm probes could be below O(10%). |
Address |
[Archidiacono, Maria] Aarhus Univ, Dept Phys & Astron, DK-8000 Aarhus C, Denmark |
Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
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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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1550-7998 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000347194400007 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
2066 |
Permanent link to this record |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Archidiacono, M.; Giusarma, E.; Melchiorri, A.; Mena, O. |
Title |
Dark radiation in extended cosmological scenarios |
Type |
Journal Article |
Year |
2012 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
Volume |
86 |
Issue |
4 |
Pages |
043509 - 7pp |
Keywords |
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Abstract |
Recent cosmological data have provided evidence for a “dark” relativistic background at high statistical significance. Parameterized in terms of the number of relativistic degrees of freedom N-eff, however, the current data seem to indicate a higher value than the one expected in the standard scenario based on three active neutrinos. This dark radiation component can be characterized not only by its abundance but also by its clustering properties, as its effective sound speed and its viscosity parameter. It is therefore crucial to study the correlations among the dark radiation properties and key cosmological parameters, as the dark energy equation of state or the running of the scalar spectral index, with current and future cosmic microwave background data. We find that dark radiation with viscosity parameters different from their standard values may be misinterpreted as an evolving dark energy component or as a running spectral index in the power spectrum of primordial fluctuations. |
Address |
[Archidiacono, Maria; Melchiorri, Alessandro] Univ Roma La Sapienza, Dept Phys, I-00185 Rome, Italy |
Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
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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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1550-7998 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000307276500002 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
1122 |
Permanent link to this record |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Archidiacono, M.; Giusarma, E.; Melchiorri, A.; Mena, O. |
Title |
Neutrino and dark radiation properties in light of recent CMB observations |
Type |
Journal Article |
Year |
2013 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
Volume |
87 |
Issue |
10 |
Pages |
103519 - 10pp |
Keywords |
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Abstract |
Recent cosmic microwave background measurements at high multipoles from the South Pole Telescope and from the Atacama Cosmology Telescope seem to disagree in their conclusions for the neutrino and dark radiation properties. In this paper we set new bounds on the dark radiation and neutrino properties in different cosmological scenarios combining the ACT and SPT data with the nine-year data release of the Wilkinson Microwave Anisotropy Probe (WMAP-9), baryon acoustic oscillation data, Hubble Telescope measurements of the Hubble constant, and supernovae Ia luminosity distance data. In the standard three massive neutrino case, the two high multipole probes give similar results if baryon acoustic oscillation data are removed from the analyses and Hubble Telescope measurements are also exploited. A similar result is obtained within a standard cosmology with N-eff massless neutrinos, although in this case the agreement between these two measurements is also improved when considering simultaneously baryon acoustic oscillation data and Hubble Space Telescope measurements. In the N-eff massive neutrino case the two high multipole probes give very different results regardless of the external data sets used in the combined analyses. When considering extended cosmological scenarios with a dark energy equation of state or with a running of the scalar spectral index, the evidence for neutrino masses found for the South Pole Telescope in the three neutrino scenario disappears for all the data combinations explored here. Again, adding Hubble Telescope data seems to improve the agreement between the two high multipole cosmic microwave background measurements considered here. In the case in which a dark radiation background with unknown clustering properties is also considered, SPT data seem to exclude the standard value for the dark radiation viscosity c(vis)(2) = 1/3 at the 2 sigma C.L., finding evidence for massive neutrinos only when combining SPT data with baryon acoustic oscillation measurements. |
Address |
Univ Aarhus, Dept Phys & Astron, DK-8000 Aarhus C, Denmark |
Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
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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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1550-7998 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000319254500004 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
1462 |
Permanent link to this record |
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Author ![sorted by Author field, descending order (down)](img/sort_desc.gif) |
Archidiacono, M.; Giusarma, E.; Hannestad, S.; Mena, O. |
Title |
Cosmic Dark Radiation and Neutrinos |
Type |
Journal Article |
Year |
2013 |
Publication |
Advances in High Energy Physics |
Abbreviated Journal |
Adv. High. Energy Phys. |
Volume |
2013 |
Issue |
|
Pages |
191047 - 14pp |
Keywords |
|
Abstract |
New measurements of the cosmic microwave background (CMB) by the Planck mission have greatly increased our knowledge about the universe. Dark radiation, a weakly interacting component of radiation, is one of the important ingredients in our cosmological model which is testable by Planck and other observational probes. At the moment, the possible existence of dark radiation is an unsolved question. For instance, the discrepancy between the value of the Hubble constant, H-0, inferred from the Planck data and local measurements of H-0 can to some extent be alleviated by enlarging the minimal ACDM model to include additional relativistic degrees of freedom. From a fundamental physics point of view, dark radiation is no less interesting. Indeed, it could well be one of the most accessible windows to physics beyond the standard model, for example, sterile neutrinos. Here, we review the most recent cosmological results including a complete investigation of the dark radiation sector in order to provide an overview of models that are still compatible with new cosmological observations. Furthermore, we update the cosmological constraints on neutrino physics and dark radiation properties focusing on tensions between data sets and degeneracies among parameters that can degrade our information or mimic the existence of extra species. |
Address |
[Archidiacono, Maria; Hannestad, Steen] Univ Aarhus, Dept Phys & Astron, DK-8000 Aarhus C, Denmark, Email: archi@phys.au.dk |
Corporate Author |
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Thesis |
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Publisher |
Hindawi Publishing Corporation |
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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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1687-7357 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000327959400001 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
1660 |
Permanent link to this record |