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The Search for Dark Matter

Published online by Cambridge University Press:  26 December 2017

Laura Baudis*
Affiliation:
Physik-Institut, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. Email: [email protected]

Abstract

The dark matter problem is almost a century old. Since the 1930s evidence has been growing that our cosmos is dominated by a new form of non-baryonic matter that holds galaxies and clusters together and influences cosmic structures up to the largest observed scales. At the microscopic level, we still do not know the composition of this dark, or invisible, matter, which does not interact directly with light. The simplest assumption is that it is made of new particles that interact with gravity and, at most, weakly with known elementary particles. I will discuss searches for such new particles, both space- and Earth-bound, including those experiments placed in deep underground laboratories. While a dark matter particle has not yet been identified, even after decades of concerted efforts, new technological developments and experiments have reached sensitivities where a discovery might be imminent, albeit certainly not guaranteed.

Type
Tribute to Thomas W.B. Kibble
Copyright
© Academia Europaea 2017 

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References

References and Notes

1.One light year is the distance travelled by light in one year: ≈ 9.5 × 1012 km.Google Scholar
2.By modern standards, there were several issues with Zwicky’s original estimate, including the wrong value of the Hubble constant, which is the current expansion rate of the Universe, crude estimates for the luminosity, the cluster radius and poor statistics; nonetheless, his main result survived, and the current value for the mass-to-light ratio (the ratio of total mass to luminosity) of galaxy clusters incidentally asymptotically approaches 400.Google Scholar
3. Zwicky, F. (1933) Die Rotverschiebung von extragalaktischen Nebeln. Helvetica Physica Acta, 6, p. 110. https://www.e-periodica.ch/digbib/view?pid=hpa-001:1933:6#112.Google Scholar
4. Rubin, V.C., Burstein, D., Ford, W.K. Jr and Thonnard, N. (1985) Rotation velocities of 16 Sa galaxies and a comparison of Sa, Sb, and Sc rotation properties. Astrophysical Journal, 289, p. 81. doi: 10.1086/162866.CrossRefGoogle Scholar
5. Bosma, A. (1981) 21-cm line studies of spiral galaxies. II. The distribution and kinematics of neutral hydrogen in spiral galaxies of various morphological types. Astronomical Journal, 86, p. 1825. doi: 10.1086/113063.CrossRefGoogle Scholar
6.Einstein first discussed the gravitational lensing by stars in 1936, while Zwicky proposed gravitational lensing by galaxies in 1937, a subject that once again was ignored until much later, until the 1970s, with the first galactic lens being discovered in 1979.Google Scholar
7.This radiation was emitted about 380,000 years after the Big Bang, when the Universe was filled with a hot, ionised gas. Once electrons combined with protons to form neutral hydrogen atoms, photons could start to travel freely through space.Google Scholar
8. Ade, P.A.R. et al. (Planck Collaboration) (2016) Planck 2015 results. XIII. Cosmological parameters. Astronomy and Astrophysics, 594, p. A13. doi: 10.1051/0004-6361/201525830.Google Scholar
9. Frieman, J.A., Turner, M.S. and Huterer, D. (2008) Dark energy and the accelerating universe. Annual Review of Astronomy and Astrophysics, 46, p. 385. doi: 10.1146/annurev.astro.46.060407.145243.CrossRefGoogle Scholar
10. Frenk, C.S. and White, S.D.M. (2012) Dark matter and cosmic structure. Annalen der Physik, 524, p. 507. doi: 10.1002/andp.201200212.Google Scholar
11.Primordial nucleosynthesis describes the formation of the light elements 2H, 3He, 4He and 7Li from about 10 s to 20 min after the Big Bang. The resulting abundances once nucleosynthesis ends, which are compared with those measured in astronomical objects where little stellar nucleosynthesis occurred, depend on the baryon-to-photon number ratio, and are thus a measure of the amount of baryons, or ordinary matter, in the early Universe.Google Scholar
12. Moniez, M. (2010) Microlensing as a probe of the Galactic structure: 20 years of microlensing optical depth studies. General Relativity and Gravitation, 42, p. 2047. doi: 10.1007/s10714-009-0925-4.CrossRefGoogle Scholar
13. Strigari, L.E. (2013) Galactic searches for dark matter. Physics Reports, 531, p. 1. doi: 10.1016/j.physrep.2013.05.004.CrossRefGoogle Scholar
14.The electronvolt (eV) is the characteristic energy scale of atomic physics processes, e.g. the ionisation energy of the hydrogen atom is 13.6 eV. The kiloelectronvolt (keV) is the energy scale of X-rays, while the megaelectronvolt (MeV) is typical for nuclear-physics processes. The gigaelectronvolt (GeV) scale is characteristic for the rest mass energy of a proton, the hydrogen atom’s nucleus, while at the LHC, the proton–proton collider near Geneva, protons are accelerated up to kinetic energies of 7000 GeV.Google Scholar
15.The abundance of dark matter is given in terms of the critical density ρ c = 3 H 0 2 M Pl 2 / (8π) = 1.88 × 10−29 g cm−3 with the Hubble constant H 0 ≈ 70 km (s Mpc) −1 and the Planck mass M Pl = 1019 GeV, namely ΩDM = ρ DM/ρ c . The critical density ρ c corresponds to about 6 hydrogen atoms per cubic metre of space.Google Scholar
16.Supersymmetry is a spacetime symmetry that proposes a relationship between particles with half-integer spin (fermions) and particles with integer spin (bosons). Examples for fermions are electrons and protons; examples for bosons are photons and gluons.Google Scholar
17.C stands for charge conjugation, P for parity transformation; the CP operation is not conserved in the weak interaction.Google Scholar
18. Peccei, R.D. and Quinn, H.R. (1977) CP conservation in the presence of pseudoparticles. Physical Review Letters, 38, p. 1440. doi: 10.1103/PhysRevLett.38.1440.CrossRefGoogle Scholar
19. Preskill, J., Wise, M.B. and Wilczek, F. (1983) Cosmology of the invisible axion. Physics Letters B, 120, p. 127. doi: 10.1016/0370-2693(83)90637-8.Google Scholar
20. Olive, K.A. et al. (Particle Data Group) (2014) Review of particle physics. Chinese Physics C, 38, p. 090001. doi: 10.1088/1674-1137/38/9/090001.Google Scholar
21. Baudis, L. (2016) Dark matter searches. Annalen der Physik, 528, p. 74. doi:10.1002/andp.201500114.Google Scholar
22. Goodman, M.W. and Witten, E. (1985) Detectability of certain dark-matter candidates. Physical Review D, 31, p. 3059. doi: 10.1103/PhysRevD.31.3059.CrossRefGoogle ScholarPubMed
23. Drukier, A., Freese, K. and Spergel, D. (1986) Detecting cold dark-matter candidates. Physical Review D, 33, p. 3495. doi: 10.1103/PhysRevD.33.3495.Google Scholar
24. Read, J.I. (2014) The local dark matter density. Journal of Physics G, 41, p. 063101. doi: 10.1088/0954-3899/41/6/063101.CrossRefGoogle Scholar
25. Baudis, L. (2012) Direct dark matter detection: The next decade. Physics of the Dark Universe, 1, p. 94. doi: 10.1016/j.dark.2012.10.006.Google Scholar
26. Sikivie, P. (ADMX Collaboration) (1983) Experimental tests of the ‘invisible’ axion. Physical Review Letters, 51, p. 1415. doi: 10.1103/PhysRevLett.51.1415.Google Scholar