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Measuring the Spin of Spiral Galaxies

Chiara Tonini·Andrea Lapi·Francesco Shankar·Paolo Salucci
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Abstract

We compute the angular momentum, the spin parameter and the related distribution function for Dark Matter halos hosting a spiral galaxy. We base on scaling laws, inferred from observations, that link the properties of the galaxy to those of the host halo; we further assume that the Dark Matter has the same total specific angular momentum of the baryons. Our main results are: (i) we find that the gas component of the disk significantly contributes to the total angular momentum of the system; (ii) by adopting for the Dark Matter the observationally supported Burkert profile, we compute the total angular momentum of the disk and its correlation with the rotation velocity; (iii) we find that the distribution function of the spin parameter $λ$ peaks at a value of about 0.03, consistent with a no-major-merger scenario for the late evolution of spiral galaxies.

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Chiara Tonini, Andrea Lapi, Francesco Shankar, Paolo Salucci. 2005-12-19. Measuring the Spin of Spiral Galaxies. https://doi.org/10.1086/500556

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