Abstract

We study the asymptotic behavior of outliers in the spectrum of bounded rank perturbations of large random matrices. In particular, we consider perturbations of elliptic random matrices which generalize both Wigner random matrices and non-Hermitian random matrices with iid entries. As a consequence, we recover the results of Capitaine, Donati-Martin, and Feral for perturbed Wigner matrices as well as the results of Tao for perturbed random matrices with iid entries. Along the way, we prove a number of interesting results concerning elliptic random matrices whose entries have finite fourth moment; these results include a bound on the least singular value and the asymptotic behavior of the spectral radius.

Highlights

  • We investigate the asymptotic behavior of outliers in the spectrum of bounded rank perturbations of large random matrices

  • We begin by introducing the empirical spectral distribution of a square matrix

  • From Theorem 1.2 and Theorem 1.5, we see that the low rank perturbation AN does not effect the limiting empirical spectral distribution (ESD)

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Summary

Introduction

We investigate the asymptotic behavior of outliers in the spectrum of bounded rank perturbations of large random matrices. We begin by introducing the empirical spectral distribution of a square matrix. ΛN (M ) denote the eigenvalues of M. In this case, the empirical spectral measure μM is given by. If the matrix M is Hermitian, the eigenvalues λ1(M ), . In this case the ESD is given by. Given a random N × N matrix YN , an important problem in random matrix theory is to study the limiting distribution of the empirical spectral measure as N tends to infinity. We will use asymptotic notation, such as O, o, Ω, under the assumption that N → ∞.

Random matrices with independent entries
Outliers in the spectrum
Elliptic random matrices
Main results
Notation
Preliminary tools and notation
Hermitization
Truncation
Martingale inequalities
Stability of the fixed point equation
Isotropic limit law
Elliptic random matrices with nonzero mean
Least singular value bound
A priori estimate
No small singular values
Diagonal entries
Off-diagonal entries
A Truncation of elliptic random matrices
B Large Deviation Estimates
C Properties of the limiting measure
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