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GRAVITATIONAL WAVE SIGNATURES OF REHEATING

Jae Hyeok Chang

Fermilab and UIC

Based on arXiv:2305.09712 �with Manuel A. Buen-Abad and Anson Hook

01/09/2024 Dark Matter as a portal to New Physics 2024, APCTP

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Chronology of �the Universe

  • We have observational data only after BBN

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  • How do we probe earlier Universe?

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  • We need a messenger from earlier Universe

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Image from https://www.ctc.cam.ac.uk/outreach/origins/big_bang_three.php

 

 

The Standard Model Prediction

BSM Prediction

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Gravitational Waves!

  • Universe is transparent to GW for all time

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  • We can probe earlier time if GW are produced from some early-time events

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  • e.g. 1st order phase transitions

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Image from https://www.ctc.cam.ac.uk/outreach/origins/big_bang_three.php

GW

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GW from 1st order PT

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GW from 1st order PT

  • GW are produced from bubble dynamics�(bubble collisions, sound waves, and turbulences)

Image from arXiv:2008.09136

Broken Phase

Broken Phase

Broken Phase

Symmetric Phase

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Toy Model for Reheating

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Temperature history during reheating

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Temperature history during reheating

 

 

 

 

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Temperature history during reheating

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Temperature history during reheating

 

 

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Temperature history during reheating

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Temperature history during reheating

Phase transition during the reheating

Phase transition during the cooling

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1st order PT during the reheating

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GW from PT during the reheating

  • GW are produced from the similar ways,�but there’re several differences

Image from arXiv:2008.09136

Symmetric Phase

Symmetric Phase

Symmetric Phase

Broken Phase

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Heating PT and Cooling PT

  • To distinguish, we define �
    • hPT as phase transition during the reheating�
    • hGW as gravitational waves from hPT�
    • cPT as Phase transition during the cooling�
    • cGW as gravitational waves from cPT

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Difference between hGW and cGW

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Difference between hGW and cGW

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Toy Model for PT

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Bubble Nucleation Rate

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Free Parameters

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Bubble Nucleation Rate

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1st order PT during the reheating

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Bubble Runaway

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Gravitation Waves from PT

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  • We consider the parameter space where bubbles runaway for hPT

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  • The dominant contribution for hGW comes from bubble collisions as it’s in the runaway regime

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  • The bubble wall for cPT has a constant wall velocity, thus sound waves dominates for cGW

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Gravitation Waves from PT

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GW Sensitivity

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arXiv:2002.04615

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Results

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Conclusions

  • 1st order phase transition may occur twice during the reheating and during the cooling

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  • If we can measure GW from both PTs, we can learn physics of reheating

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  • In this work, we study the properties of GW production during the reheating

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THANK YOU