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WIMP diffusion in the Solar System including solar WIMP-nucleon scattering
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
Stockholm University.
2012 (English)In: Physical Review D, ISSN 1550-7998, Vol. 85, no 12, 123514- p.Article in journal (Refereed) Published
Abstract [en]

Dark matter in the form of Weakly Interacting Massive Particles (WIMPs) can be captured by the Sun and the Earth, sink to their cores, annihilate and produce neutrinos that can be searched for with neutrino telescopes. The calculation of the capture rates of WIMPs in the Sun and especially the Earth are affected by large uncertainties coming mainly from effects of the planets in the Solar System, reducing the capture rates by up to an order of magnitude (or even more in some cases). We show that the WIMPs captured by weak scatterings in the Sun also constitute an important bound WIMP population in the Solar System. Taking this population and its interplay with the population bound through gravitational diffusion into account cancel the planetary effects on the capture rates, and the capture essentially proceeds as if the Sun and the Earth were free in the galactic halo. The neutrino signals from the Sun and the Earth are thus significantly higher than claimed in the scenarios with reduced capture rates.

Place, publisher, year, edition, pages
2012. Vol. 85, no 12, 123514- p.
Keyword [en]
National Category
Subatomic Physics
URN: urn:nbn:se:kth:diva-70238DOI: 10.1103/PhysRevD.85.123514ISI: 000304941200005ScopusID: 2-s2.0-84862285317OAI: diva2:486118
Swedish Research Council, 621-2010-3301Swedish Research Council, 315-2004-6519
QC 20120130. Updated from submitted to published.Available from: 2012-01-30 Created: 2012-01-30 Last updated: 2012-07-03Bibliographically approved
In thesis
1. Studies of dark matter in and around stars
Open this publication in new window or tab >>Studies of dark matter in and around stars
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

There is by now compelling evidence that most of the matter in the Universe is in the form of dark matter, a form of matter quite different from the matter we experience in every day life. The gravitational effects of this dark matter have been observed in many different ways but its true nature is still unknown. In most models, dark matter particles can annihilate with each other into standard model particles; the direct or indirect observation of such annihilation products could give important clues for the dark matter puzzle. For signals from dark matter annihilations to be detectable, typically high dark matter densities are required. Massive objects, such as stars, can increase the local dark matter density both via scattering off nucleons and by pulling in dark matter gravitationally as a star forms. Annihilations within this kind of dark matter population gravitationally bound to a star, like the Sun, give rise to a gamma ray flux. For a star which has a planetary system, dark matter can become gravitationally bound also through gravitational interactions with the planets. The interplay between the different dark matter populations in the solar system is analyzed, shedding new light on dark matter annihilations inside celestial bodies and improving the predicted experimental reach. Dark matter annihilations inside a star would also deposit energy in the star which, if abundant enough, could alter the stellar evolution. This is investigated for the very first stars in the Universe. Finally, there is a possibility for abundant small scale dark matter overdensities to have formed in the early Universe. Prospects of detecting gamma rays from such minihalos, which have survived until the present day, are discussed.

Abstract [sv]

Kosmologiska observationer har visat att större delen av materian i universum består av mörk materia, en form av materia med helt andra egenskaper än den vi upplever i vardagslivet. Effekterna av denna mörka materia har observerats gravitationellt på många olika sätt men vad den egentligen består av är fortfarande okänt. I de flesta modeller kan mörk materia-partiklar annihilera med varandra till standardmodellpartiklar. Att direkt eller indirekt observera sådana annihilationsprodukter kan ge viktiga ledtrådar om vad den mörka materian består av. För att kunna detektera sådana signaler fordras typiskt höga densiteter av mörk materia. Stjärnor kan lokalt öka densiteten av mörk materia, både via spridning mot atomkärnor i stjärnan och genom den ökande gravitationskraften i samband med att en stjärna föds. Annihilationer inom en sådan mörk materia-population gravitationellt bunden till en stjärna, till exempel solen, ger upphov till ett flöde av gammastrålning, som beräknas. För en stjärna som har ett planetsystem kan mörk materia även bli infångad genom gravitationell växelverkan med planeterna. Samspelet mellan de två mörk materia-populationerna i solsystemet analyseras, vilket ger nya insikter om mörk materia-annihilationer inuti himlakroppar och förbättrar de experimentella möjligheterna att detektera dem. Mörk materia-annihilationer inuti en stjärna utgör också en extra energikälla för stjärnan, vilket kan påverka stjärnans utveckling om mörk materia-densiteten blir tillräckligt stor. Denna effekt undersöks för de allra första stjärnorna i universum. Slutligen finns det också en möjlighet att det i det tidiga universum skapades mörk materia-ansamlingar som fortfarande finns kvar idag. Utsikterna att upptäcka dessa genom mätning av gammastrålning diskuteras.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. x, 73 p.
Trita-FYS, ISSN 0280-316X ; 2012:04
Dark matter, particle astrophysics
National Category
Physical Sciences
urn:nbn:se:kth:diva-64245 (URN)987-91-7501-251-3 (ISBN)
Public defence
2012-02-17, FB42, AlbaNova universitetscentrum, Roslagstullsbacken 21, AlbaNova, Stockholm, 13:00 (English)
QC 20120130Available from: 2012-01-30 Created: 2012-01-24 Last updated: 2012-01-30Bibliographically approved

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