The Brauer-Manin obstruction on algebraic stacks

Abstract

For algebraic stacks over number fields, we define their Brauer-Manin sets, Brauer-Manin pairings, and extend the descent theory of Colliot-Thélène and Sansuc. By extending Sansuc's exact sequence, we show the torsionness of Brauer groups of stacks that are locally quotients of varieties by linear groups. With mild assumptions, for stacks that are locally quotients or Deligne-Mumford, we show that the Brauer-Manin obstruction coincides with some other cohomological obstructions such as obstructions given by torsors under connected groups or abelian gerbes. For Brauer-Manin sets of these stacks, we show the properties such as descent along a torsor, product preservation are still correct. These results extend classical theories of those on varieties.

25 pages, supplements additional citations and proofs, such as cohomological descent, representability of contracted products, and other general revisions. (git commit a496eec)