Lectures on Gravitational Waves from the Early Universe

2 Jun 2021, 15:00 → 4 Jun 2021, 18:00 Asia/Seoul

Hyun Min Lee (CAU - Chung-Ang University (KR))

Lecturer: Dr. Kai Schmitz (CERN)

Abstract:

The field of gravitational-wave astronomy has seen rapid and impressive progress since the first direct detection of gravitational waves in 2015; and yet the exciting journey has just begun. In the coming decades, gravitational waves will continue to expand their role as an indispensable tool for astrophysics and cosmology and advance to a primary probe of fundamental physics in the 21st century. In light of these prospects, this lecture series will highlight some of the exciting new physics scenarios that we might be able to discover in the gravitational-wave sky, with a special focus on gravitational waves from the early Universe. After a general introduction to gravitational waves in general relativity (Lecture I) and an overview of ongoing and future gravitational-wave experiments and observations (Lecture II), we will turn to particle cosmology and possible cosmological sources of stochastic gravitational-wave backgrounds, in particular, primordial gravitational waves from cosmic inflation (Lecture III), first-order phase transitions (Lecture IV), and cosmic defects (Lecture V). To conclude, we will discuss the recently announced NANOGrav signal and its possible interpretations and give an outlook onto the future of the field (Lecture VI).

***

Lecture I: Definition and properties of GWs in general relativity

Topics: GWs in linearized gravity, propagation of GWs in the expanding Universe, stochastic GW backgrounds in cosmology

 

Lecture II: Overview of existing and future GW experiments, basics behind the data analysis

Topics: GW interferometers, experimental sensitivity curves, pulsar timing arrays, cosmic microwave background

 

Lecture III: GWs in big-bang and inflationary cosmology

Topics: Bounds on the integrated GW energy density, amplification of primordial tensor perturbations during inflation, transfer function

 

Lecture IV: GWs from strong first-order phase transitions in the early Universe

Topics: GW signal from runaway and non-runaway phase transitions, models, sensitivity curves

 

Lecture V: GWs from cosmic defects

Topics: Introduction to cosmic defects, GW signal from a general defect network, GWs from cosmic strings

 

Lecture VI: NANOGrav signal, possible interpretations, outlook onto the field in the coming years

Topics: Overview of the NANOGrav measurement, possible astrophysical and BSM interpretations, upcoming pulsar timing data

 

 

*** Recommended reading before the lecture series:

 

I recommend to have a look at the nontechnical introductions on the following websites:

 

https://www.ligo.org/science.php
https://www.elisascience.org/articles/gravitational-wave-astronomy
http://nanograv.org/research/

and to skim through the following technical review paper:

Stochastic Gravitational-Wave Backgrounds
Nelson Christensen
https://arxiv.org/abs/1811.08797

*** Literature / further reading:

[1] Cosmological Backgrounds of Gravitational Waves
Chiara Caprini, Daniel G. Figueroa
https://arxiv.org/abs/1801.04268

[2] Detection Methods for Stochastic Gravitational-Wave Backgrounds: A Unified Treatment
Joseph D. Romano, Neil J. Cornish
https://arxiv.org/abs/1608.06889

[3] Gravitational Waves from Inflation
Maria Chiara Guzzetti, Nicola Bartolo, Michele Liguori, Sabino Matarrese
https://arxiv.org/abs/1605.01615

[4] Phase Transitions in the Early Universe
Mark B. Hindmarsh, Marvin Lüben, Johannes Lumma, Martin Pauly
https://arxiv.org/abs/2008.09136

[5] Probing the Gravitational-Wave Background from Cosmic Strings with LISA
Pierre Auclair et al. (LISA Cosmology Working Group)
https://arxiv.org/abs/1909.00819

[6] Gravitational-Wave Research Using Pulsar Timing Arrays
George Hobbs, Shi Dai
https://arxiv.org/abs/1707.01615

***

Organizers:

Ki-Young Choi (Sungkyunkwan Univ)

Hyun Min Lee (Chung-Ang Univ)

Seong Chan Park (Yonsei Univ)

***

Zoom links:

 

June 2 (Day 1): https://cau.zoom.us/j/82358987538?pwd=bmk1dXMvek41M1MvOVFnbmFYcThUZz09

Meeting ID: 823 5898 7538
Passcode: CAUGW

 

June 3 (Day 2): https://cau.zoom.us/j/87626528924?pwd=REZWL1o4YlFCVXl3UDNYUUNUeTVidz09

Meeting ID: 876 2652 8924
Passcode: CAUGW

 

June 4 (Day 3): https://cau.zoom.us/j/82582443348?pwd=OXR4anQ3N3pWY3RwNFdIR3dEZUc2UT09

Meeting ID: 825 8244 3348
Passcode: CAUGW

 

***

 

Wednesday 2 June

1 Lecture I: Definition and properties of GWs in general relativity

GWs in linearized gravity, propagation of GWs in the expanding Universe, stochastic GW backgrounds in cosmology.

Speaker: Dr Kai Schmitz (CERN)

lecture_1a.pdf

recorded talk

16:15 Coffee break and discussion

2 Lecture II: Overview of existing and future GW experiments, basics behind the data analysis

GW interferometers, experimental sensitivity curves, pulsar timing arrays, cosmic microwave background

Speaker: Dr Kai Schmitz (CERN)

lecture_1b.pdf

recorded talk

Thursday 3 June

3 Lecture III: GWs in big-bang and inflationary cosmology

Bounds on the integrated GW energy density, amplification of primordial tensor perturbations during inflation, transfer function

Speaker: Dr Kai Schmitz (CERN)

lecture_2a.pdf

recorded talk

16:15 Coffee break and discussion

4 Lecture IV: GWs from strong first-order phase transitions in the early Universe

GW signal from runaway and non-runaway phase transitions, models, sensitivity curves

Speaker: Dr Kai Schmitz (CERN)

lecture_2b.pdf

recorded talk

Friday 4 June

5 Lecture V: GWs from cosmic defects

Introduction to cosmic defects, GW signal from a general defect network, GWs from cosmic strings

Speaker: Dr Kai Schmitz (CERN)

lecture_3a.pdf

recorded talk

16:15 Coffee break and discussion

6 Lecture VI: NANOGrav signal, possible interpretations, outlook onto the field in the coming years

Overview of the NANOGrav measurement, possible astrophysical and BSM interpretations, upcoming pulsar timing data

Speaker: Dr Kai Schmitz (CERN)

lecture_3b.pdf

recorded talk