Quantitative spectral gap for thin groups of hyperbolic isometries
Author(s) -
Michael Magee
Publication year - 2015
Publication title -
journal of the european mathematical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.549
H-Index - 64
eISSN - 1435-9863
pISSN - 1435-9855
DOI - 10.4171/jems/500
Subject(s) - mathematics , pure mathematics , spectral gap , relatively hyperbolic group , mathematical analysis , hyperbolic manifold , hyperbolic function
Let ΛΛ be a subgroup of an arithmetic lattice in SO(n+1,1)SO(n+1,1). The quotient Hn+1/ΛHn+1/Λ has a natural family of congruence covers corresponding to ideals in a ring of integers. We establish a super-strong approximation result for Zariski-dense ΛΛ with some additional regularity and thickness properties. Concretely, this asserts a quantitative spectral gap for the Laplacian operators on the congruence covers. This generalizes results of Sarnak and Xue (1991) and Gamburd (2002)
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