Volume 612, April 2018
|Number of page(s)||6|
|Section||Letters to the Editor|
|Published online||04 May 2018|
Letter to the Editor
The angular momentum-mass relation: a fundamental law from dwarf irregulars to massive spirals★
Kapteyn Astronomical Institute, University of Groningen,
PO Box 800,
Groningen, The Netherlands
2 Research School of Astronomy and Astrophysics – The Australian National University, Canberra, ACT 2611, Australia
3 Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland
Accepted: 12 April 2018
In a Λ CDM Universe, the specific stellar angular momentum (j*) and stellar mass (M*) of a galaxy are correlated as a consequence of the scaling existing for dark matter haloes (jh ∝2∕3). The shape of this law is crucial to test galaxy formation models, which are currently discrepant especially at the lowest masses, allowing to constrain fundamental parameters, such as, for example, the retained fraction of angular momentum. In this study, we accurately determine the empirical j*−M* relation (Fall relation) for 92 nearby spiral galaxies (from S0 to Irr) selected from the Spitzer Photometry and Accurate Rotation Curves (SPARC) sample in the unprecedented mass range 7 ≲ log M*∕M⊙≲ 11.5. We significantly improve all previous estimates of the Fall relation by determining j* profiles homogeneously for all galaxies, using extended HI rotation curves, and selecting only galaxies for which a robust j* could be measured (converged j*(<R) radial profile). We find the relation to be well described by a single, unbroken power-law j* α M*α over the entire mass range, with α = 0.55 ± 0.02 and orthogonal intrinsic scatter of 0.17 ± 0.01 dex. We finally discuss some implications of this fundamental scaling law for galaxy formation models and, in particular, the fact that it excludes models in which discs of all masses retain the same fraction of the halo angular momentum.
Key words: galaxies: kinematics and dynamics / galaxies: spiral / galaxies: structure / galaxies: formation
The data used in Fig. 2 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/612/L6
© ESO 2018
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