S Hannestad et al- Cosmological constraints on neutrino plus axion hot dark matter: update after WMAP-5

8/3/2019 S Hannestad et al- Cosmological constraints on neutrino plus axion hot dark matter: update after WMAP-5

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ournal of Cosmology and Astroparticle PhysicsAn IOP and SISSA journal

Cosmological constraints on neutrinoplus axion hot dark matter: updateafter WMAP-5

S Hannestad1, A Mirizzi2, G G Raffelt2 and Y Y Y Wong2

1 Department of Physics and Astronomy, University of Aarhus, DK-8000Aarhus C, Denmark2 Max-Planck-Institut fur Physik (Werner-Heisenberg-Institut), Fohringer Ring6, D-80805 Munchen, GermanyE-mail: [email protected], [email protected], [email protected] [email protected]

Received 11 March 2008Accepted 25 March 2008

Published 15 April 2008

Online at stacks.iop.org/JCAP/2008/i=04/a=019doi:10.1088/1475-7516/2008/04/019

Abstract. We update our previous constraints on two-component hot darkmatter (axions and neutrinos), including the recent WMAP five-year data release.Marginalizing over

m provides ma < 1.02 eV (95% C.L.) for the axion mass.

In the absence of axions we findm

< 0.63 eV (95% C.L.).

Keywords: dark matter, cosmological neutrinos, axions

c2008 IOP Publishing Ltd and SISSA 1475-7516/08/04019+3$30.00
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]://stacks.iop.org/JCAP/2008/i=04/a=019http://stacks.iop.org/JCAP/2008/i=04/a=019mailto:[email protected]:[email protected]:[email protected]:[email protected]


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Cosmological constraints on neutrino plus axion hot dark matter

Very recently the Wilkinson Microwave Anisotropy Probe (WMAP) experiment haspublished its five-year result for the angular power spectra of the temperature and thepolarization variations of the cosmic microwave background radiation, superseding theirprevious three-year measurements [1, 2]. We use this opportunity to update our previouslimits on the cosmological abundance of hot dark matter in the form of ordinary neutrinosas well as axions [3]. We recall that axions in the eV mass range thermally decouple afterthe QCD phase transition and thus form a hot dark matter component. Cold dark matteraxions, on the other hand, have much smaller masses, corresponding to a much largerPecceiQuinn scale. These axions are produced nonthermally before and during the QCDphase transition. Our update concerns the former variety of hot, thermal axions, and isperformed for the benefit of those interested in limits based on the latest set of data.

The analysis of the WMAP five-year data (WMAP-5) is performed using version 3

of the likelihood calculation package provided by the WMAP team on the LAMBDAhomepage [4], and follows closely the analyses of [5, 6]. Other datasets used in this workand our parameter estimation methodology are described in our previous paper [3], inwhich we also provide references to the literature.

We consider here only the baseline case of our previous study: we do not includeinformation from the Lyman- forest, and use only standard axion couplings to pions.Figure 1 shows our results in the form of 2D marginal 68% and 95% contours in the

m

ma plane. The blue/solid lines are our updated contours, the red/dashed lines are

Figure 1. 2D marginal 68% and 95% contours in themma plane derived

from the standard dataset of our previous paper (excluding the Lyman- forest).The blue/solid lines correspond to our new results using WMAP-5, while thered/dashed lines are our previous constraints derived from WMAP-3.

Journal of Cosmology and Astroparticle Physics 04 (2008) 019 (stacks.iop.org/JCAP/2008/i=04/a=019) 2
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our previous results using the WMAP three-year data (WMAP-3). The modifications arevery minor. Marginalizing over neutrino masses, our new axion mass limit is

ma < 1.02 eV (95% C.L.), (1)

about 20% tighter than our previous limit. Conversely, the neutrino mass limit aftermarginalization over the axion mass is

m< 0.59 eV (95% C.L.), (2)

which is identical to our old result.These changes are also reflected in the 2D contours in figure 1, where a shrinkage

in the allowed region in the ma direction, but not in the

m

direction, is apparent.The reason for this is a better measurement of the early integrated SachsWolfe effect byWMAP-5, which in turn limits any nonstandard effect due to extra light free-streaming

species around the epoch of matterradiation equality. For comparison, we also derive anew neutrino mass limit assuming a complete absence of axions:

m< 0.63 eV (95% C.L.). (3)

These limits are expected to become more restrictive with the inclusion of smaller-scale data such as the Lyman- forest which, however, we consider too vulnerable tosystematic uncertainties. We also note that the WMAP-5 favoured value of 8 is slightlylarger than the WMAP-3 value [6]. The very strong neutrino mass bound obtained in [7]from the inclusion of Lyman- arose partially because the 8 value inferred from theSDSS Lyman- data is significantly higher than that from WMAP-3. Therefore the fact

that the WMAP-5 and the SDSS Lyman-

measurements of8

are in better agreementpresumably will relax the hot dark matter mass bound from the CMB + Lyman- datato some extent.

Acknowledgments

We acknowledge use of computing resources from the Danish Center for ScientificComputing (DCSC) and partial support by the European Union under the ILIAS project(contract no. RII3-CT-2004-506222), by the Deutsche Forschungsgemeinschaft undergrant TR-27 Neutrinos and Beyond and by The Cluster of Excellence for FundamentalPhysics Origin and Structure of the Universe (Garching and Munich). AM is supportedby a grant of the Alexander von Humboldt Foundation.

References

[1] Hinshaw G et al, Five-year Wilkinson Microwave Anisotropy Probe (WMAP) observations: data processing,sky maps, and basic results, 2008 Preprint 0803.0732 [astro-ph]

[2] Nolta M R et al, Five-year Wilkinson Microwave Anisotropy Probe (WMAP) observations: angular powerspectra, 2008 Preprint 0803.0593 [astro-ph]

[3] Hannestad S, Mirizzi A, Raffelt G G and Wong Y Y Y, Cosmological constraints on neutrino plus axion hotdark matter, 2007 J. Cosmol. Astropart. Phys. JCAP08(2007)015 [SPIRES] [0706.4198] [astro-ph]

[4] Legacy Archive for Microwave Background Data Analysis (LAMBDA), http://lambda.gsfc.nasa.gov[5] Dunkley J et al (WMAP Collaboration), Five-year Wilkinson Microwave Anisotropy Probe (WMAP)

observations: likelihoods and parameters from the WMAP data, 2008 Preprint 0803.0586 [astro-ph][6] Komatsu E et al, Five-year Wilkinson Microwave Anisotropy Probe (WMAP) observations: cosmological

interpretation, 2008 Preprint 0803.0547 [astro-ph][7] Seljak U, Slosar A and McDonald P, Cosmological parameters from combining the Lyman-alpha forest with

CMB, galaxy clustering and SN constraints, 2006 J. Cosmol. Astropart. Phys. JCAP10(2006)014[SPIRES] [astro-ph/0604335]

Journal of Cosmology and Astroparticle Physics 04 (2008) 019 (stacks.iop.org/JCAP/2008/i=04/a=019) 3
http://arxiv.org/abs/0803.0732http://arxiv.org/abs/0803.0593http://dx.doi.org/10.1088/1475-7516/2007/08/015http://www-spires.slac.stanford.edu/spires/find/hep/www?j=JCAPA%2C0708%2C015http://www-spires.slac.stanford.edu/spires/find/hep/www?j=JCAPA%2C0708%2C015http://arxiv.org/abs/0706.4198http://arxiv.org/abs/0706.4198http://lambda.gsfc.nasa.gov/http://arxiv.org/abs/0803.0586http://arxiv.org/abs/0803.0547http://dx.doi.org/10.1088/1475-7516/2006/10/014http://www-spires.slac.stanford.edu/spires/find/hep/www?j=JCAPA%2C0610%2C014http://www-spires.slac.stanford.edu/spires/find/hep/www?j=JCAPA%2C0610%2C014http://arxiv.org/abs/astro-ph/0604335http://arxiv.org/abs/astro-ph/0604335http://arxiv.org/abs/astro-ph/0604335http://stacks.iop.org/JCAP/2008/i=04/a=019http://stacks.iop.org/JCAP/2008/i=04/a=019http://stacks.iop.org/JCAP/2008/i=04/a=019http://arxiv.org/abs/astro-ph/0604335http://www-spires.slac.stanford.edu/spires/find/hep/www?j=JCAPA%2C0610%2C014http://dx.doi.org/10.1088/1475-7516/2006/10/014http://arxiv.org/abs/0803.0547http://arxiv.org/abs/0803.0586http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://lambda.gsfc.nasa.gov/http://arxiv.org/abs/0706.4198http://www-spires.slac.stanford.edu/spires/find/hep/www?j=JCAPA%2C0708%2C015http://dx.doi.org/10.1088/1475-7516/2007/08/015http://arxiv.org/abs/0803.0593http://arxiv.org/abs/0803.0732

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S Hannestad et al- Cosmological constraints on neutrino plus axion hot dark matter: update after WMAP-5