Dark and baryonic matter moved at different velocities in the early Universe, which strongly suppressed star formation in some regions1. This was estimated2 to imprint a large-scale fluctuation signal of about two millikelvin in the 21-centimetre spectral line of atomic hydrogen associated with stars at a redshift of 20, although this estimate ignored the critical contribution of gas heating due to X-rays3,4 and major enhancements of the suppression. A large velocity difference reduces the abundance of haloes1,5,6 and requires the first stars to form in haloes of about a million solar masses7,8, substantially greater than previously expected9,10. Here we report a simulation of the distribution of the first stars at redshift 20 (cosmic age of around 180 million years), incorporating all these ingredients within a 400-megaparsec box. We find that the 21-centimetre hydrogen signature of these stars is an enhanced (ten millikelvin) fluctuation signal on the hundred-megaparsec scale, characterized2 by a flat power spectrum with prominent baryon acoustic oscillations. The required sensitivity to see this signal is achievable with an integration time of a thousand hours with an instrument like the Murchison Wide-field Array11 or the Low Frequency Array12 but designed to operate in the range of 50–100 megahertz.
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
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)
Dalal, N., Pen, U.-L. & Seljak, U. Large-scale BAO signatures of the smallest galaxies. J. Cosmol. Astroparticle Phys. 11, 007 (2010)
Madau, P., Meiksin, A. & Rees, M. J. 21 centimeter tomography of the intergalactic medium at high redshift. Astrophys. J. 475, 429–444 (1997)
Pritchard, J. R. & Furlanetto, S. 21-cm fluctuations from inhomogeneous X-ray heating before reionization. Mon. Not. R. Astron. Soc. 376, 1680–1694 (2007)
Maio, U., Koopmans, L. V. E. & Ciardi, B. The impact of primordial supersonic flows on early structure formation, reionization and the lowest-mass dwarf galaxies. Mon. Not. R. Astron. Soc. 412, L40–L44 (2011)
Naoz, S., Yoshida, N. & Gnedin, N. Y. Simulations of early baryonic structure formation with stream velocity: I. Halo abundance. Astrophys. J. 747, 128 (2012)
Stacy, A., Bromm, C. & Loeb, A. Effect of streaming motion of baryons relative to dark matter on the formation of the first stars. Astrophys. J. 730, L1 (2011)
Greif, T., White, S., Klessen, R. & Springel, V. The delay of population III star formation by supersonic streaming velocities. Astrophys. J. 736, 147 (2011)
Abel, T., Bryan, G. L. & Norman, M. L. The formation of the first star in the Universe. Science 295, 93–98 (2002)
Bromm, V., Coppie, P. S. & Larson, R. B. Forming the first stars in the Universe: The fragmentation of primordial gas. Astrophys. J. 527, L5–L8 (1999)
Bowman, J. D., Morales, M. F. & Hewitt, J. N. Foreground contamination in interferometric measurements of the redshifted 21 cm power spectrum. Astrophys. J. 695, 183–199 (2009)
Harker, G. et al. Power spectrum extraction for redshifted 21-cm Epoch of Reionization experiments: the LOFAR case. Mon. Not. R. Astron. Soc. 405, 2492–2504 (2010)
Tseliakhovich, D., Barkana, R. & Hirata, C. Suppression and spatial variation of early galaxies and minihalos. Mon. Not. R. Astron. Soc. 418, 906–915 (2011)
Fialkov, A., Barkana, R., Tseliakhovich, D. & Hirata, C. Impact of the Relative Motion between Dark Matter and Baryons on the First Stars. Mon. Not. R. Astron. Soc. (submitted); preprint at http://arxiv.org/abs/1110.2111.
Naoz, S., Noter, S. & Barkana, R. The first stars in the Universe. Mon. Not. R. Astron. Soc. 373, L98–L102 (2006)
Holzbauer, L. N. & Furlanetto, S. R. Fluctuations in the high-redshift Lyman-Werner and Lyman-alpha radiation backgrounds. Mon. Not. R. Astron. Soc. 419, 718–731 (2012)
Mesinger, A., Furlanetto, S. & Cen, R. 21CMFAST: a fast, seminumerical simulation of the high-redshift 21-cm signal. Mon. Not. R. Astron. Soc. 411, 955–972 (2011)
Barkana, R. & Loeb, A. Unusually large fluctuations in the statistics of galaxy formation at high redshift. Astrophys. J. 609, 474–481 (2004)
Aihara, H. et al. The eighth data release of the Sloan Digital Sky Survey: first data from SDSS-III. Astrophys. J. Suppl. 193, 29 (2011); erratum. 195, 26 (2011)
Colless, M. et al. The 2dF Galaxy Redshift Survey: spectra and redshifts. Mon. Not. R. Astron. Soc. 328, 1039–1063 (2001)
Springel, V., Frenk, C. S. & White, S. D. M. The large-scale structure of the Universe. Nature 440, 1137–1144 (2006)
Haiman, Z., Rees, M. J. & Loeb, A. Destruction of molecular hydrogen during cosmological reionization. Astrophys. J. 476, 458–463 (1997); erratum. 484, 985 (1997)
Barkana, R. & Loeb, A. Detecting the earliest galaxies through two new sources of 21 centimeter fluctuations. Astrophys. J. 626, 1–11 (2005)
Naoz, S. & Barkana, R. Detecting early galaxies through their 21-cm signature. Mon. Not. R. Astron. Soc. 385, L63–L67 (2008)
Furlanetto, S. R., Oh, S. P. & Briggs, F. H. Cosmology at low frequencies: the 21 cm transition and the high-redshift Universe. Phys. Rep. 433, 181–301 (2006)
Bouwens, R. J. et al. A candidate redshift z ≈ 10 galaxy and rapid changes in that population at an age of 500 Myr. Nature 469, 504–507 (2011)
Anderson, L. et al. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: baryon acoustic oscillations in the Data Release 9 Spectroscopic Galaxy Sample. Preprint at http://arxiv.org/abs/1203.6594 (2012)
Barkana, R., Haiman, Z. & Ostriker, J. P. Constraints on warm dark matter from cosmological reionization. Astrophys. J. 558, 482–496 (2001)
McQuinn, M., Zahn, O., Zaldarriaga, M., Hernquist, L. & Furlanetto, S. R. Cosmological parameter estimation using 21 cm radiation from the epoch of reionization. Astrophys. J. 653, 815–834 (2006)
Liu, A. & Tegmark, M. How well can we measure and understand foregrounds with 21-cm experiments? Mon. Not. R. Astron. Soc. 419, 3491 (2012)
This work was supported by the Israel Science Foundation (for R.B., and E.V.’s stay at Tel Aviv University) and by the European Research Council (for A.F.). D.T. and C.M.H. were supported by the US Department of Energy and the National Science Foundation. C.M.H. is also supported by the David & Lucile Packard Foundation.
The authors declare no competing financial interests.
This file contains Supplementary Text and Data 1-4, which comprises 1) a description of the simulation code; 2) a comparison with previous work on the dark matter to baryon velocity difference; 3) the expected timing of the three high-redshift feedback transitions and 4) observational considerations. Supplementary Figure 1 (on the Lyman-Werner feedback) and additional references are also included. (PDF 252 kb)
About this article
Cite this article
Visbal, E., Barkana, R., Fialkov, A. et al. The signature of the first stars in atomic hydrogen at redshift 20. Nature 487, 70–73 (2012) doi:10.1038/nature11177
The Astrophysical Journal (2019)
Physical Review Letters (2019)
Titans of the early Universe: The Prato statement on the origin of the first supermassive black holes
Publications of the Astronomical Society of Australia (2019)
Physical Review D (2019)
Physical Review D (2019)