nLab
elliptic fibration

Contents

Idea

An elliptic fibration is a bundle of elliptic curves, possibly including some singular fibers.

An elliptic surface is an elliptic fibration over an algebraic curve.

Properties

Classification by local systems with modular group coefficients

Write SL 2()SL_2(\mathbb{Z}) for the special linear group in dimension 2 with integer coefficients and write SL 2()PSL 2()SL_2(\mathbb{Z}) \to PSL_2(\mathbb{Z}) for the projection to the corresponding projective linear group. Regarding this as the Möbius group it comes with its natural action on the upper half plane 𝔥\mathfrak{h}. The homotopy quotient ell()=𝔥//SL 2()\mathcal{M}_{ell}(\mathbb{C}) = \mathfrak{h}//SL_2(\mathbb{Z}) is the moduli stack of elliptic curves over the complex numbers.

Accordingly, to any SL 2()SL_2(\mathbb{Z})-principal bundle PBP \to B (necessarily flat since SL 2()SL_2(\mathbb{Z}) is a discrete group, hence a “local system”) is associated a 𝔥\mathfrak{h}-fiber bundle such that a section of it defines a non-singular elliptic fibration.

One may turn this around: Given an elliptic fibration EBE \to B, then away from the points SBS\subset B over which the fiber is singular, it is given by an SL 2()SL_2(\mathbb{Z})-local system together with a section of the associated upper-half plane bundle on BSB-S.

With due technical care, this data uniquely characterizes the elliptic fibration (e.g. Miranda 88, prop. VI.3.3).

References

  • Wikipedia, elliptic surface

  • Rick Miranda, The basic theory of elliptic surfaces, lecture notes 1988 (pdf)

  • Viacheslav Nikulin, Elliptic fibrations on K3 surfaces (arXiv:1010.3904)

  • Fedor Bogomolov, Yuri Tschinkel, Monodromy of elliptic surfaces (pdf)

  • Takahiko Yoshida, Locally standard torus fibrations pdf

Revised on May 16, 2014 03:47:26 by Urs Schreiber (31.55.19.118)