Axion Dark Matter from Cosmic String Network

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Hauptverfasser: Kim, Heejoo, Park, Junghyeon, Son, Minho
Format: Preprint
Veröffentlicht: 2024
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author Kim, Heejoo
Park, Junghyeon
Son, Minho
author_facet Kim, Heejoo
Park, Junghyeon
Son, Minho
contents We perform the lattice simulation to estimate the axion dark matter abundance radiated from the global cosmic strings in the post-inflationary scenario. The independent numerical confirmation on the recently observed logarithmic growth in both the number of strings per Hubble patch and the spectral index of the power law scaling for the axion spectrum is reported. These logarithmic scalings are checked against two different prescriptions for generating initial random field configurations, namely fat-string type and thermal phase transition. We discuss a possible strong correlation between the axion spectrum and the string evolutions with different initial conditions to support the insensitivity of scaling behaviors against different initial data and we provide a qualitative understanding of it. The impact of various combinations of the power law of the axion spectrum, nonlinearities around the QCD scale, and average inter-string distances on the axion abundance is discussed. Additionally, we introduce a new novel string identification method, based on the tetrahedralization of the space, which guarantees the connectedness of the strings and provides a convenient way of assigning the core location. Finally we derive the lower bound on the axion mass.
format Preprint
id arxiv_https___arxiv_org_abs_2402_00741
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Axion Dark Matter from Cosmic String Network
Kim, Heejoo
Park, Junghyeon
Son, Minho
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
We perform the lattice simulation to estimate the axion dark matter abundance radiated from the global cosmic strings in the post-inflationary scenario. The independent numerical confirmation on the recently observed logarithmic growth in both the number of strings per Hubble patch and the spectral index of the power law scaling for the axion spectrum is reported. These logarithmic scalings are checked against two different prescriptions for generating initial random field configurations, namely fat-string type and thermal phase transition. We discuss a possible strong correlation between the axion spectrum and the string evolutions with different initial conditions to support the insensitivity of scaling behaviors against different initial data and we provide a qualitative understanding of it. The impact of various combinations of the power law of the axion spectrum, nonlinearities around the QCD scale, and average inter-string distances on the axion abundance is discussed. Additionally, we introduce a new novel string identification method, based on the tetrahedralization of the space, which guarantees the connectedness of the strings and provides a convenient way of assigning the core location. Finally we derive the lower bound on the axion mass.
title Axion Dark Matter from Cosmic String Network
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2402.00741