Galaxies are complex systems the evolution of which apparently results from the interplay of dynamics, star formation, chemical enrichment and feedback from supernova explosions and supermassive black holes1. The hierarchical theory of galaxy formation holds that galaxies are assembled from smaller pieces, through numerous mergers of cold dark matter2,3,4. The properties of an individual galaxy should be controlled by six independent parameters including mass, angular momentum, baryon fraction, age and size, as well as by the accidents of its recent haphazard merger history. Here we report that a sample of galaxies that were first detected through their neutral hydrogen radio-frequency emission, and are thus free from optical selection effects5, shows five independent correlations among six independent observables, despite having a wide range of properties. This implies that the structure of these galaxies must be controlled by a single parameter, although we cannot identify this parameter from our data set. Such a degree of organization appears to be at odds with hierarchical galaxy formation, a central tenet of the cold dark matter model in cosmology6.
This is a preview of subscription content
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.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
de Jong, R. S. (ed.) Island Universes: Structure and Evolution of Disk Galaxies (Astrophys. Space Sci. Proc., Springer, 2007)
Baugh, C. M. A primer on hierarchical galaxy formation: the semi-analytical approach. Rep. Prog. Phys. 69, 3101–3156 (2006)
Dalcanton, J. J., Spergel, D. N. & Summers, I. J. The formation of disk galaxies. Astrophys. J. 482, 659–676 (1997)
Mo, H. J., Mao, S. & White, S. D. M. The formation of galactic discs. Mon. Not. R. Astron. Soc. 295, 319–336 (1998)
Disney, M. J. in The Low Surface Brightness Universe (eds Davies, J. I., Impey, C. & Phillipps, S.) 9–18 (IAU Symp. 171, Astron. Soc. Pacif. Conf. Ser. 170, Astronomical Society of the Pacific, 1999)
Blumenthal, G. R., Faber, S. M., Primack, J. R. & Rees, M. J. Formation of galaxies and large-scale structure with cold dark matter. Nature 311, 517–525 (1984)
Staveley-Smith, L. et al. The Parkes 21-cm multibeam receiver. Publ. Astron. Soc. Austral. 13, 243–248 (1996)
Zwaan, M. A. et al. The HIPASS catalogue – II. Completeness, reliability, and parameter accuracy. Mon. Not. R. Astron. Soc. 350, 1210–1219 (2004)
Meyer, M. J. et al. The HIPASS catalogue – I. Data presentation. Mon. Not. R. Astron. Soc. 350, 1195–1209 (2004)
Adelman-McCarthy, J. K. et al. The fifth data release of the Sloan Digital Sky Survey. Astrophys. J. Suppl. Ser. 172, 634–644 (2007)
Garcia-Appadoo, D. A., West, A. A., Dalcanton, J. J., Cortese, L. & Disney, M. J. Correlations among the properties of galaxies found in a blind HI survey. Mon. Not. R. Astron. Soc (submitted); preprint at 〈http://arxiv.org/abs/0809.1434〉 (2008)
Strateva, I. et al. Color separation of galaxy types in the Sloan Digital Sky Survey imaging data. Astron. J. 122, 1861–1874 (2001)
Kulkarni, S. R. & Heiles, C. in Galactic and Extra-Galactic Radio Astronomy 2nd edn (eds Kellerman, K. I. & Verschuur, G. L.) 95–153 (Springer, 1988)
Gavazzi, G., Pierini, D. & Boselli, A. The phenomenology of disk galaxies. Astron. Astrophys. 312, 397–408 (1996)
Blanton, M. R. et al. The galaxy luminosity function and luminosity density at redshift z = 0.1. Astrophys. J. 592, 819–838 (2003)
van der Kruit, P. The three-dimensional distribution of light and mass in disks of spiral galaxies. Astron. Astrophys. 192, 117–127 (1988)
Haynes, M. P. & Giovanelli, R. Neutral hydrogen in isolated galaxies. IV – Results for the Arecibo sample. Astron. J. 89, 758–800 (1984)
Rosenberg, J. L., Schneider, S. E. & Posson-Brown, J. Gas and stars in an HI-selected galaxy sample. Astrophys. J. 129, 1311–1330 (2005)
Jolliffe, I. T. Principal Component Analysis (Springer, 1986)
Chatfield, C. & Collins, A. J. Introduction to Multivariate Analysis (Chapman & Hall, 1980)
Kormendy, J. & Kennicutt, R. C. Secular evolution and the formation of pseudobulges in disk galaxies. Annu. Rev. Astron. Astrophys. 42, 603–683 (2004)
Zibetti, S. et al. 1.65 micron (H band) surface photometry of galaxies. I. Structural and dynamical properties of elliptical galaxies. Astrophys. J. 579, 261–269 (2002)
Conselice, C. J. The fundamental properties of galaxies and a new galaxy classification system. Mon. Not. R. Astron. Soc. 373, 1389–1408 (2006)
Brosche, P. The manifold of galaxies. Galaxies with known dynamical parameters. Astron. Astrophys. 23, 259–268 (1973)
Balkowski, C. Statistical study of integral properties of galaxies measured in the 21-cm line. Astron. Astrophys. 29, 43–55 (1973)
Bujarrabal, V., Guibert, J. & Balkowski, C. Multidimensional statistical analysis of normal galaxies. Astron. Astrophys. 104, 1–9 (1981)
Shostak, G. S. Integral properties of late-type galaxies derived from HI observations. Astron. Astrophys. 68, 321–341 (1978)
Whitmore, B. C. An objective classification system for spiral galaxies. I. The two dominant dimensions. Astrophys. J. 278, 61–80 (1984)
Dalcanton, J. J., Spergel, D. N., Gunn, J. E., Schmidt, M. & Schneider, D. P. The number density of low-surface brightness galaxies with 23 < μ0 25 V Mag/arcsec2 . Astron. J. 114, 635–654 (1997)
We would like to thank the HIPASS team, and especially R. Ekers, A. Wright and L. Staveley-Smith of the Australian National Telescope at CSIRO Radiophysics in Sydney for their foresight and enterprise in getting the Multibeam project started. M.J.D. would like to thank M. Disney of the Geography Department at University College London for first pointing out the one-dimensional nature of this data.
About this article
Cite this article
Disney, M., Romano, J., Garcia–Appadoo, D. et al. Galaxies appear simpler than expected. Nature 455, 1082–1084 (2008). https://doi.org/10.1038/nature07366
Nature Astronomy (2018)