Stochastic Gravitational Wave Background from Global Cosmic Strings

Chang, Chia-Feng; Cui, Yanou

doi:10.48550/arxiv.1910.04781

Cited by 8 publications

(17 citation statements)

References 49 publications

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“…Further phenomenological consequences for both QCD axion and general ALPs are worth further exploration. Meanwhile a caveat for the scenario of post-inflationary PQ-breaking is that, as in conventional misalignment, topological defects' contribution to the axion relic density may dominate over the misalignment contribution, and is worth revisiting to advance and complete our understanding of the axion production mechanism [14,17,20,37,38].…”

Section: Discussionmentioning

confidence: 99%

New Perspectives on Axion Misalignment Mechanism

Chang,

Cui

2019

Preprint

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A zero initial velocity of the axion field is assumed in the conventional misalignment mechanism. We propose an alternative scenario where the initial velocity is nonzero, which may arise from an explicit breaking of the PQ symmetry in the early Universe. We demonstrate that, depending on the specifics about the initial velocity and the time order of the PQ symmetry breaking vs. inflation, this new scenario can alter the conventional prediction for the axion relic abundance in different, potentially significant ways. As a result, new viable parameter regions for axion dark matter may open up.

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Section: Discussionmentioning

confidence: 99%

New Perspectives on Axion Misalignment Mechanism

Chang,

Cui

2019

Preprint

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“…Furthermore, the detection of a cosmogenic SGWB can potentially address many long-standing questions in particle physics and cosmology (e.g. [19][20][21][22][23][24][25][26][27][28][29][30][31]), and allows us to probe very early stages of the Universe.…”

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confidence: 99%

“…Very recently, inspired by its intimate connections to axion dark matter physics, significant progress has been made in simulating global topological defects and on the GW signals originated from it [42][43][44][45][46]. With a semianalytical approach based on the Velocity-dependent One-Scale (VOS) model, our earlier work [24] demonstrated that the GW signal from global strings, albeit notably smaller than that from its NG string counterpart, can be within reach of future GW experiments such as LISA [6,7], AEDGE [47], DECIGO and BBO [48]. Such a positive prospect of detection has been confirmed by simulation-based work [45,46], although details differ which will be addressed in this work.…”

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confidence: 99%

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Gravitational Waves from Global Cosmic Strings and Cosmic Archaeology

Chang,

Cui

2021

Preprint

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Global cosmic strings are predicted in many motivated extensions to the Standard Model of particle physics, with close connections to axion dark matter physics. Recent studies suggest that, although subdominant relative to Goldstone emission, gravitational wave (GW) signals from global strings can be detectable with current and planned GW detectors such as LIGO, LISA, DECIGO/BBO, ET/CE and AEDGE/AION, as well as pulsar timing arrays such as PPTA, NANOGrav and SKA. This work is an extensive, updated study on GWs from a global cosmic string network, taking into account of the most recent developments related to the subject. The main analysis is based on the analytical Velocity-dependent One-Scale (VOS) model calibrated with recent simulation results, which provides a generic protocol for such calculations with details given. We also demonstrate how the GW signal can be influenced with variations to the baseline model: this includes considering the uncertainties of model parameters and the potential deviation from the conventional VOS model prediction (i.e. the scaling behavior) as suggested by some of the recent simulation results. Furthermore, we investigated in detail the effect of a non-standard cosmology (e.g. early matter domination or kination) or new particle species on the GW signals from global strings. We demonstrate that the frequency spectrum of GW background from global cosmic strings can be used to probe the cosmic history prior to the Big Bang nucleosynthesis (BBN) (i.e. the primordial dark age) up to a temperature of T ∼ 10 8 GeV.

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“…A weak logarithmic time-dependence of the tension is common for global cosmic strings. See[10] and references therein 2. The former option with µ ∼ H 2 has been considered in Ref [11]…”

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confidence: 99%

Gravitational waves from melting cosmic strings

Emond,

Ramazanov,

Samanta

2021

Preprint

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Appearance of cosmic strings in the early Universe is a common manifestation of new physics typically linked to some high energy scale. In this paper, we discuss a different situation, where a model underlying cosmic string formation is approximately scale free. String tension is naturally related to the square of the temperature of the hot primordial plasma in such a setting, and hence decreases with (cosmic) time. With gravitational backreaction neglected, the dynamics of these melting strings in an expanding Universe is equivalent to the dynamics of constant tension strings in a Minkowski spacetime. We provide an estimate for the emission of gravitational waves from string loops. Contrary to the standard case, the resulting spectrum is markedly non-flat and has a characteristic falloff at frequencies below the peak one. The peak frequency is defined by the underlying model and lies in the range accessible by the future detectors for very weak couplings involved.

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Stochastic Gravitational Wave Background from Global Cosmic Strings

Cited by 8 publications

References 49 publications

New Perspectives on Axion Misalignment Mechanism

New Perspectives on Axion Misalignment Mechanism

Gravitational Waves from Global Cosmic Strings and Cosmic Archaeology

Gravitational waves from melting cosmic strings

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