We consider the dynamics of fibred quadratic polynomials over an irrational rotation of the circle. We construct a simple mechanism, so-called critical connection, that implies non-hyperbolicity. To exhibit that critical connection is a robust property in the parameter space of fibred quadratic polynomials over a fixed irrational rotation of the circle. Since there exist fibred quadratic polynomials that have such phenomena, we conclude that hyperbolicity is non-dense in this sense. In order to obtain our main results, we prove that, in the hyperbolic case, the filled-in Julia set varies continuously with the fibres. Even though the existence of robust mechanisms that give rise to non-hyperbolicity is a technique that has become standard, the novelty of this work has to do with the fact that we were able to establish this mechanism in a polynomial family of degree $ 2 $ of the complex plane, fibred over a non-chaotic map.
| Citation: |
| [1] |
M. Astorg and F. Bianchi, Higher bifurcations for polynomial skew products, Journal of Modern Dynamics, 18 (2022), 69-99.
doi: 10.3934/jmd.2022003.
|
| [2] |
M. Astorg and F. Bianchi, Hyperbolicity and Bifurcations in holomorphic families of polynomial skew products, American Journal of Mathematics, 145 (2023), 861-898.
doi: 10.1353/ajm.2023.a897498.
|
| [3] |
A. M. Benini, A survey on MLC Rigidity and related topics, preprint, 2017, arXiv: 1709.09869.
|
| [4] |
S. Biebler, Newhouse phenomenon for automorphisms of low degree in $ \mathbb{C}^3$, Adv. Math., 361 (2020), 106952.
doi: 10.1016/j.aim.2019.106952.
|
| [5] |
G. T. Buzzard, Nondensity of stability for polynomial automorphisms of $ \mathbb{C}^2$, Indiana University Mathematics Journal, 48 (1999), 857-865.
doi: 10.1512/iumj.1999.48.1656.
|
| [6] |
G. T. Buzzard and A. Jenkins, Holomorphic motions and structural stability for polynomial automorphisms of $ \mathbb{C}^2$, Indiana University Mathematics Journal, 145 (2001), 277-308.
doi: 10.1512/iumj.2008.57.3252.
|
| [7] |
R. Dujardin, A non-laminar dynamical Green current, Mathematische Annalen, 365 (2016), 77-91.
doi: 10.1007/s00208-015-1274-0.
|
| [8] |
R. Dujardin, Non-density of stability for holomorphic mappings on $\mathbb {P}^ k$, Journal de l'École Polytechnique-Mathématiques, 4 (2017), 813-843.
doi: 10.5802/jep.57.
|
| [9] |
N. Fagella, A. Jorba, M. Jorba-Cuscó and J. C. Tatjer, Classification of linear skew-products of the complex plane and an affine route to fractalization, Discrete and Continuous Dynamical Systems-Series A, 39 (2019), 3767-3787.
doi: 10.3934/dcds.2019153.
|
| [10] |
J. Graczyk and G. Światek, Fine structure of connectedness loci, Math. Ann., 369 (2017), 49-108.
doi: 10.1007/s00208-016-1446-6.
|
| [11] |
J. H. Hubbard, Local connectivity of Julia sets and bifurcation loci: Three theorems of J. C. Yoccoz., Topological Methods in Modern Mathematics, ed. Golberg and Phillips, Publish or Perish, 1993,467-511.
|
| [12] |
T. Jäger, Strange non-chaotic attractors in quasiperiodically forced circle maps, Comm. Math. Phys., 289 (2009), 253-289.
doi: 10.1007/s00220-009-0753-0.
|
| [13] |
M. Jonsson, Dynamics of polynomial skew products on $ \mathbb{C}$, Math. Ann., 314 (1999), 403-447.
doi: 10.1007/s002080050301.
|
| [14] |
M. Jonsson, Ergodic properties of fibered rational maps, Ark. Mat., 38 (2000), 281-317.
doi: 10.1007/BF02384321.
|
| [15] |
M. Lyubich, Dynamics of quadratic polynomials Ⅰ, Ⅱ, Ⅲ, Acta Math., 178 (1997), 185-257,247-297, and Astérisque, 261, 173-200
doi: 10.1007/BF02392694.
|
| [16] |
Ch. Pommerenke, Univalent Functions, Vandenhoeck & Ruprecht, Göttingen, 1975. With a chapter on quadratic differentials by Gerd Jensen, Studia Mathematica/Mathematische Lehrbücher, Band XXV.
|
| [17] |
M. Ponce, Local dynamics for fibred holomorphic transformations, Nonlinearity, 20 (2007), 2939-2955.
doi: 10.1088/0951-7715/20/12/011.
|
| [18] |
M. Ponce, Courbes Invariantes Pour les Dynamiques Holomorphes Fibrées, Ph.D thesis, Université Paris XI., 2007.
|
| [19] |
M. Ponce, Fibred quadratic polynomials can admit two attracting invariant curves, Proc. Amer. Math. Soc., 139 (2011), 1467-1468.
doi: 10.1090/S0002-9939-2010-10574-9.
|
| [20] |
O. Sester, Hyperbolicité des polynômes fibrés, Bull. Soc. Math. France, 127 (1999), 393-428.
|
| [21] |
O. Sester, Combinatorial configurations of fibered polynomials, Ergodic Theory Dynam. Systems, 21 (2007), 915-955.
doi: 10.1017/S0143385701001456.
|
| [22] |
J. Stark, Invariant graphs for forced systems, Physics and dynamics between chaos, order, and noise, Phys. D, 109 (1997), 163-179.
doi: 10.1016/S0167-2789(97)00167-X.
|
| [23] |
J. Taflin, Blenders near polynomial product maps of $\mathbb{C}^2$, J. Eur. Math. Soc., 23 (2021), 3555-3589.
doi: 10.4171/JEMS/1076.
|
| [24] |
M. Viana, Multidimensional nonhyperbolic attractors, Inst. Hautes Études Sci. Publ. Math., 85 (1997), 63-96.
|