Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

A small amount of mini-charged dark matter could cool the baryons in the early Universe

Abstract

The dynamics of our Universe is strongly influenced by pervasive—albeit elusive—dark matter, with a total mass about five times the mass of all the baryons1,2. Despite this, its origin and composition remain a mystery. All evidence for dark matter relies on its gravitational pull on baryons, and thus such evidence does not require any non-gravitational coupling between baryons and dark matter. Nonetheless, some small coupling would explain the comparable cosmic abundances of dark matter and baryons3, as well as solving structure-formation puzzles in the pure cold-dark-matter models4. A vast array of observations has been unable to find conclusive evidence for any non-gravitational interactions of baryons with dark matter5,6,7,8,9. Recent observations by the EDGES collaboration, however, suggest that during the cosmic dawn, roughly 200 million years after the Big Bang, the baryonic temperature was half of its expected value10. This observation is difficult to reconcile with the standard cosmological model but could be explained if baryons are cooled down by interactions with dark matter, as expected if their interaction rate grows steeply at low velocities11. Here we report that if a small fraction—less than one per cent—of the dark matter has a mini-charge, a million times smaller than the charge on the electron, and a mass in the range of 1–100 times the electron mass, then the data10 from the EDGES experiment can be explained while remaining consistent with all other observations. We also show that the entirety of the dark matter cannot have a mini-charge.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Regions of the mini-charged-particle parameter space explored by 21-cm observations, and current constraints.
Fig. 2: Brightness temperature of 21-cm emission as a function of redshift.

Similar content being viewed by others

References

  1. Ade, P. A. R. et al. Planck 2015 results. XIII. Cosmological parameters. Astron. Astrophys. 594, A13 (2015).

    Google Scholar 

  2. Rubin, V. C., Ford, W. K. Jr & Thonnard, N. Rotational properties of 21 SC galaxies with a large range of luminosities and radii, from NGC 4605/R = 4 kpc/ to UGC 2885/R = 122 kpc/. Astrophys. J. 238, 471–487 (1980).

    Article  ADS  CAS  Google Scholar 

  3. Kaplan, D. B. A Single explanation for both the baryon and dark matter densities. Phys. Rev. Lett. 68, 741–743 (1992).

    Article  PubMed  ADS  CAS  Google Scholar 

  4. Weinberg, D. H., Bullock, J. S., Governato, F., Kuzio de Naray, R. & Peter, A. H. G. Cold dark matter: controversies on small scales. Proc. Natl Acad. Sci. USA 112, 12249–12255 (2015).

    Article  PubMed  PubMed Central  ADS  CAS  Google Scholar 

  5. Akerib, D. S. et al. Limits on spin-dependent WIMP–nucleon cross section obtained from the complete LUX exposure. Phys. Rev. Lett. 118, 251302 (2017).

    Article  PubMed  ADS  CAS  Google Scholar 

  6. Ackermann, M. et al. The Fermi Galactic Center GeV excess and implications for dark matter. Astrophys. J. 840, 43 (2017).

    Article  ADS  CAS  Google Scholar 

  7. Dvorkin, C., Blum, K. & Kamionkowski, M. Constraining dark matter–baryon scattering with linear cosmology. Phys. Rev. D 89, 023519 (2014).

    Article  ADS  CAS  Google Scholar 

  8. Fox, P. J., Harnik, R., Kopp, J. & Tsai, Y. LEP shines light on dark matter. Phys. Rev. D 84, 014028 (2011).

    Article  ADS  CAS  Google Scholar 

  9. Muñoz, J. B. & Loeb, A. Constraints on dark matter–baryon scattering from the temperature evolution of the intergalactic medium. J. Cosmol. Astropart. Phys. 1711, 043 (2017).

    Article  ADS  Google Scholar 

  10. Bowman, J., Rogers, A. E. E., Monsalve, R. A., Mozdzen, T. J. & Mahesh, N. An absorption profile centred at 78 megahertz in the sky-averaged spectrum. Nature 555, 67–70 (2018).

    Article  PubMed  ADS  CAS  Google Scholar 

  11. Barkana, R. Possible interaction between baryons and dark-matter particles revealed by the first stars. Nature 555, 71–74 (2018).

    Article  PubMed  ADS  CAS  Google Scholar 

  12. Loeb, A. & Furlanetto, S. R. The First Galaxies in the Universe (Princeton Univ. Press, Princeton, 2013).

    Book  MATH  Google Scholar 

  13. Wouthuysen, S. A. On the excitation mechanism of the 21-cm (radio-frequency) interstellar hydrogen emission line. Astron. J. 57, 31–32 (1952).

    Article  ADS  CAS  Google Scholar 

  14. Field, G. B. The spin temperature of intergalactic neutral hydrogen. Astrophys. J. 129, 536–550 (1959).

    Article  ADS  CAS  Google Scholar 

  15. Furlanetto, S., Oh, S. P. & Briggs, F. Cosmology at low frequencies: the 21 cm transition and the high-redshift universe. Phys. Rep. 433, 181–301 (2006).

    Article  ADS  CAS  Google Scholar 

  16. Chuzhoy, L. & Kolb, E. W. Reopening the window on charged dark matter. J. Cosmol. Astropart. Phys. 0907, 014 (2009).

    Article  ADS  CAS  Google Scholar 

  17. Jansson, R. & Farrar, G. R. A new model of the galactic magnetic field. Astrophys. J. 757, 14 (2012).

    Article  ADS  Google Scholar 

  18. Bovy, J. & Tremaine, S. On the local dark matter density. Astrophys. J. 756, 89 (2012).

    Article  ADS  Google Scholar 

  19. Cline, J. M., Liu, Z. & Xue, W. Millicharged atomic dark matter. Phys. Rev. D 85, 101302 (2012).

    Article  ADS  CAS  Google Scholar 

  20. McDermott, S. D., Yu, H.-B. & Zurek, K. M. Turning off the lights: how dark is dark matter? Phys. Rev. D 83, 063509 (2011).

    Article  ADS  CAS  Google Scholar 

  21. Tseliakhovich, D. & Hirata, C. Relative velocity of dark matter and baryonic fluids and the formation of the first structures. Phys. Rev. D 82, 083520 (2010).

    Article  ADS  CAS  Google Scholar 

  22. Muñoz, J. B., Kovetz, E. D. & Ali-Haïmoud, Y. Heating of baryons due to scattering with dark matter during the dark ages. Phys. Rev. D 92, 083528 (2015).

    Article  ADS  CAS  Google Scholar 

  23. Ali-Haïmoud, Y. & Hirata, C. M. HyRec: A fast and highly accurate primordial hydrogen and helium recombination code. Phys. Rev. D 83, 043513 (2011).

    Article  ADS  CAS  Google Scholar 

  24. Davidson, S., Hannestad, S. & Raffelt, G. Updated bounds on millicharged particles. J. High Energy Phys. 05, 003 (2000).

    Article  ADS  Google Scholar 

  25. Essig, R. et al. Working Group Report: New Light Weakly Coupled Particles. Available at https://arxiv.org/abs/1311.0029 (2013).

  26. Prinz, A. A. et al. Search for millicharged particles at SLAC. Phys. Rev. Lett. 81, 1175–1178 (1998).

    Article  ADS  CAS  Google Scholar 

  27. Dolgov, A. D., Dubovsky, S. L., Rubtsov, G. I. & Tkachev, I. I. Constraints on millicharged particles from Planck data. Phys. Rev. D 88, 117701 (2013).

    Article  ADS  CAS  Google Scholar 

  28. Jaeckel, J. & Ringwald, A. The low-energy frontier of particle physics. Annu. Rev. Nucl. Part. Sci. 60, 405–437 (2010).

    Article  ADS  CAS  Google Scholar 

  29. Vogel, H. & Redondo, J. Dark radiation constraints on mini-charged particles in models with a hidden photon. J. Cosmol. Astropart. Phys. 1402, 029 (2014).

    Article  ADS  Google Scholar 

  30. DeBoer, D. R. et al. Hydrogen Epoch of Reionization Array (HERA). Publ. Astron. Soc. Pacif. 129, 045001 (2017).

    Article  ADS  Google Scholar 

  31. Clarke, T. E., Kronberg, P. P. & Boehringer, H. A new radio-X-ray probe of galaxy cluster magnetic fields. Astrophys. J. 547, L111–L114 (2001).

    Article  ADS  CAS  Google Scholar 

  32. Heikinheimo, M., Raidal, M., Spethmann, C. & Veermäe, H. Dark matter self-interactions via collisionless shocks in cluster mergers. Phys. Lett. B 749, 236–241 (2015).

    Article  ADS  CAS  Google Scholar 

  33. Kadota, K., Sekiguchi, T. & Tashiro, H. A new constraint on millicharged dark matter from galaxy clusters. Preprint at https://arxiv.org/abs/1602.04009 (2016).

  34. Tashiro, H., Kadota, K. & Silk, J. Effects of dark matter–baryon scattering on redshifted 21 cm signals. Phys. Rev. D 90, 083522 (2014).

    Article  ADS  CAS  Google Scholar 

  35. Peebles, P. J. E. Recombination of the primeval plasma. Astrophys. J. 153, 1 (1968).

    Article  ADS  Google Scholar 

  36. Ali-Haimoud, Y. & Hirata, C. M. Ultrafast effective multi-level atom method for primordial hydrogen recombination. Phys. Rev. D 82, 063521 (2010).

    Article  ADS  CAS  Google Scholar 

  37. Chluba, J. & Thomas, R. M. Towards a complete treatment of the cosmological recombination problem. Mon. Not. R. Astron. Soc. 412, 748–764 (2011).

    ADS  Google Scholar 

  38. Slatyer, T. R. Energy injection and absorption in the cosmic dark ages. Phys. Rev. D 87, 123513 (2013).

    Article  ADS  CAS  Google Scholar 

  39. Ma, C.-P. & Bertschinger, E. Cosmological perturbation theory in the synchronous and conformal Newtonian gauges. Astrophys. J. 455, 7–25 (1995).

    Article  ADS  CAS  Google Scholar 

  40. Holdom, B. & Two, U. 1)’s and epsilon charge shifts. Phys. Lett. B 166, 196–198 (1986).

    Article  ADS  Google Scholar 

  41. Batell, B. & Gherghetta, T. Localized U(1) gauge fields, millicharged particles, and holography. Phys. Rev. D 73, 045016 (2006).

    Article  MathSciNet  ADS  CAS  Google Scholar 

  42. Brust, C., Kaplan, D. E. & Walters, M. T. New light species and the CMB. J. High Energy Phys. 12, 058 (2013).

    Article  ADS  CAS  Google Scholar 

  43. D’Agnolo, R. T. & Ruderman, J. T. Light dark matter from forbidden channels. Phys. Rev. Lett. 115, 061301 (2015).

    Article  PubMed  ADS  CAS  Google Scholar 

  44. Erickcek, A. L., Steinhardt, P. J., McCammon, D. & McGuire, P. C. Constraints on the interactions between dark matter and baryons from the X-ray Quantum Calorimetry Experiment. Phys. Rev. D 76, 042007 (2007).

    Article  ADS  CAS  Google Scholar 

  45. Wagner, T. A., Schlamminger, S., Gundlach, J. H. & Adelberger, E. G. Torsion-balance tests of the weak equivalence principle. Class. Quantum Gravity 29, 184002 (2012).

    Article  ADS  Google Scholar 

  46. Pritchard, J. R. & Loeb, A. Evolution of the 21 cm signal throughout cosmic history. Phys. Rev. D 78, 103511 (2008).

    Article  ADS  CAS  Google Scholar 

  47. Madau, P., Meiksin, A. & Rees, M. J. 21-cm tomography of the intergalactic medium at high redshift. Astrophys. J. 475, 429 (1997).

    Article  ADS  Google Scholar 

  48. Pritchard, J. R. & Loeb, A. Constraining the unexplored period between the dark ages and reionization with observations of the global 21 cm signal. Phys. Rev. D 82, 023006 (2010).

    Article  ADS  CAS  Google Scholar 

  49. Cohen, A., Fialkov, A. & Barkana, R. Charting the parameter space of the 21-cm power spectrum. Preprint at https://arxiv.org/abs/1709.02122(2017).

  50. Lindhard, J. & Scharff, M. Energy dissipation by ions in the keV region. Phys. Rev. 124, 128–130 (1961).

    Article  ADS  CAS  Google Scholar 

  51. Harvey, D., Massey, R., Kitching, T., Taylor, A. & Tittley, E. The non-gravitational interactions of dark matter in colliding galaxy clusters. Science 347, 1462–1465 (2015).

    Article  PubMed  ADS  CAS  Google Scholar 

  52. Knapen, S., Lin, T. & Zurek, K. M. Light dark matter: models and constraints. Phys. Rev. D 96, 115021 (2017).

    Article  ADS  Google Scholar 

  53. Stubbs, C. W. et al. Search for an intermediate-range interaction. Phys. Rev. Lett. 58, 1070–1073 (1987).

    Article  PubMed  ADS  CAS  Google Scholar 

Download references

Acknowledgements

We thank P. Agrawal, Y. Ali-Haïmoud, C. Dvorkin, M. Kamionkowski, D. Pinner, C. Stubbs and S. Westerdale for discussions. This research is supported in part by the Black Hole Initiative, which is funded by a JTF grant.

Author information

Authors and Affiliations

Authors

Contributions

J.B.M. performed the calculations and wrote the code, with assistance from A.L. Both authors wrote the manuscript.

Corresponding author

Correspondence to Julian B. Muñoz.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Muñoz, J.B., Loeb, A. A small amount of mini-charged dark matter could cool the baryons in the early Universe. Nature 557, 684–686 (2018). https://doi.org/10.1038/s41586-018-0151-x

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41586-018-0151-x

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing