We prove that a sum of two odd irreducible two-dimensional Galois representations with squarefree relatively prime Serre conductors is attached to a Hecke eigenclass in the homology of a subgroup of , with the level, nebentype, and coefficient module of the homology predicted by a generalization of Serre’s conjecture to higher dimensions. To do this we prove along the way that any Hecke eigenclass in the homology of a congruence subgroup of a maximal parabolic subgroup of has a reducible Galois representation attached, where the dimensions of the components correspond to the type of the parabolic subgroup. Our main new tool is a resolution of by -modules consisting of sums of Steinberg modules for all subspaces of .
Mots clés : Galois representations, arithmetic homology
Avner Ash 1 ; Darrin Doud 2
@article{AMBP_2018__25_2_207_0, author = {Avner Ash and Darrin Doud}, title = {Reducible {Galois} representations and arithmetic homology for $\protect \mathrm{GL}(4)$}, journal = {Annales math\'ematiques Blaise Pascal}, pages = {207--246}, publisher = {Universit\'e Clermont Auvergne, Laboratoire de math\'ematiques Blaise Pascal}, volume = {25}, number = {2}, year = {2018}, doi = {10.5802/ambp.375}, language = {en}, url = {https://ambp.centre-mersenne.org/articles/10.5802/ambp.375/} }
TY - JOUR AU - Avner Ash AU - Darrin Doud TI - Reducible Galois representations and arithmetic homology for $\protect \mathrm{GL}(4)$ JO - Annales mathématiques Blaise Pascal PY - 2018 SP - 207 EP - 246 VL - 25 IS - 2 PB - Université Clermont Auvergne, Laboratoire de mathématiques Blaise Pascal UR - https://ambp.centre-mersenne.org/articles/10.5802/ambp.375/ DO - 10.5802/ambp.375 LA - en ID - AMBP_2018__25_2_207_0 ER -
%0 Journal Article %A Avner Ash %A Darrin Doud %T Reducible Galois representations and arithmetic homology for $\protect \mathrm{GL}(4)$ %J Annales mathématiques Blaise Pascal %D 2018 %P 207-246 %V 25 %N 2 %I Université Clermont Auvergne, Laboratoire de mathématiques Blaise Pascal %U https://ambp.centre-mersenne.org/articles/10.5802/ambp.375/ %R 10.5802/ambp.375 %G en %F AMBP_2018__25_2_207_0
Avner Ash; Darrin Doud. Reducible Galois representations and arithmetic homology for $\protect \mathrm{GL}(4)$. Annales mathématiques Blaise Pascal, Tome 25 (2018) no. 2, pp. 207-246. doi : 10.5802/ambp.375. https://ambp.centre-mersenne.org/articles/10.5802/ambp.375/
[1] Galois representations attached to mod cohomology of , Duke Math. J., Volume 65 (1992) no. 2, pp. 235-255 | DOI | MR
[2] Unstable cohomology of , J. Algebra, Volume 167 (1994) no. 2, pp. 330-342 | DOI | MR
[3] Direct sums of characters of and the homology of , Commun. Algebra, Volume 41 (2013) no. 5, pp. 1751-1775 | DOI | MR
[4] Comparison of Steinberg modules for a field and a subfield, J. Algebra, Volume 507 (2018), pp. 200-224 | DOI | MR
[5] Reducible Galois representations and the homology of , Int. Math. Res. Not., Volume 5 (2014), pp. 1379-1408 | MR
[6] Galois representations attached to tensor products of arithmetic cohomology, J. Algebra, Volume 465 (2016), pp. 81-99 | DOI | MR
[7] Relaxation of strict parity for reducible Galois representations attached to the homology of , Int. J. Number Theory, Volume 12 (2016) no. 2, pp. 361-381 | DOI | MR
[8] Galois representations with conjectural connections to arithmetic cohomology, Duke Math. J., Volume 112 (2002) no. 3, pp. 521-579 | DOI | MR
[9] Torsion in the cohomology of congruence subgroups of and Galois representations, J. Algebra, Volume 325 (2011), pp. 404-415 | DOI | MR
[10] An analogue of Serre’s conjecture for Galois representations and Hecke eigenclasses in the mod cohomology of , Duke Math. J., Volume 105 (2000) no. 1, pp. 1-24 | DOI | MR
[11] Cohomology of arithmetic groups and congruences between systems of Hecke eigenvalues, J. Reine Angew. Math., Volume 365 (1986), pp. 192-220 | MR
[12] Modular representations of , symmetric squares, and mod- cohomology of , J. Algebra, Volume 222 (1999) no. 2, pp. 376-399 | DOI | MR
[13] Corners and arithmetic groups, Comment. Math. Helv., Volume 48 (1973), pp. 436-491 | DOI | MR | Zbl
[14] Cohomology of groups, Graduate Texts in Mathematics, 87, Springer, 1994, x+306 pages | MR
[15] The composition factors of as a -module, J. Algebra, Volume 147 (1992) no. 2, pp. 411-441 | DOI | MR
[16] The weight in a Serre-type conjecture for tame -dimensional Galois representations, Duke Math. J., Volume 149 (2009) no. 1, pp. 37-116 | DOI | MR
[17] Modular representations of finite groups of Lie type, London Mathematical Society Lecture Note Series, 326, Cambridge University Press, 2006, xvi+233 pages | MR
[18] Serre’s modularity conjecture. I, Invent. Math., Volume 178 (2009) no. 3, pp. 485-504 | DOI | MR
[19] Serre’s modularity conjecture. II, Invent. Math., Volume 178 (2009) no. 3, pp. 505-586 | DOI | MR
[20] Modularity of 2-adic Barsotti-Tate representations, Invent. Math., Volume 178 (2009) no. 3, pp. 587-634 | DOI | MR
[21] A course in the theory of groups, Graduate Texts in Mathematics, 80, Springer, 1996, xviii+499 pages | DOI | MR
[22] On torsion in the cohomology of locally symmetric varieties, Ann. Math., Volume 182 (2015) no. 3, pp. 945-1066 | DOI | MR
[23] Sur les représentations modulaires de degré de , Duke Math. J., Volume 54 (1987) no. 1, pp. 179-230 | DOI | MR
[24] Introduction to the arithmetic theory of automorphic functions, Publications of the Mathematical Society of Japan, 11, Princeton University Press, 1994, xiv+271 pages | MR | Zbl
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