David Weir [he/him/his] - davidjamesweir

University of Helsinki

Jyväskylä, 24.1.2020

Credit: Stephan Paul, arXiv:1205.2451

Credit: Stephan Paul, arXiv:1205.2451

Credit: Stephan Paul, arXiv:1205.2451

gravitational waves help?

Stretches and squeezes a ring of matter

$\Leftrightarrow$Sources: [CC-BY-SA] Nico 0692 on Wikimedia Commons; ESA / C. Carreau

A: By moving mass and energy around quickly.

[cf. electromagnetic waves, made by moving electrons]

A: They change the *proper length $L$* between test
masses, so producing a *strain* $\Delta
L/L$.

[in fact gravitational waves obey a form of Hooke's
law]

1993 Nobel Prize

Credit: Shane Larson

Solid line - prediction; red dots -
measurements

Source: [PD] Wikimedia Commons

Source: [PD] NASA

Source:
(CC-BY) Andrea
Nguyen on Flickr

Sources:
[PD] LIGO
Lab/Caltech/MIT; Umptanum
on Wikimedia Commons

Source:
(CC-BY) Phys. Rev. Lett. 116,
061102

Source:
(CC-BY) Phys. Rev. Lett. 116,
061102

Credit: Christopher Evans/Georgia Tech

Source: [CC-BY]

ApJL, 848:L12, 2017

ApJL, 848:L12, 2017

and cosmology

- Photons arrived 1.7s later, after travelling
140 M ly

⇒ gravitational waves travel at the speed of light - Independent measurement of universe's expansion:
- Known luminosity of gravitational waves → distance
- Telescopes observe host galaxy → redshift; velocity

need to go into space!

- Three laser arms, 2.5 M km separation
- ESA led, launching before 2034
- Mission adopted 2017 arXiv:1702.00786

Source: [PD] NASA via Wikimedia Commons

Source: [CC-BY-SA] Nicolas Douillet on Wikimedia Commons

Credit: LISA proposal

Source: [PD] Dana Berry on Wikimedia Commons

Source: arXiv:1907.00014

Science Investigation 7.2: Measure, or set upper limits on, the spectral shape of the cosmological stochastic GW background.

Operational Requirement 7.2:Probe a broken power-law stochastic background from the early Universe as predicted, for example, by first order phase transitions ...

- Process by which the Higgs 'switched on'
- In the Standard Model it is a crossover
- Possible in extensions that it would be
*first order*

➥ colliding bubbles then make gravitational waves

Credit:
[FDL] GRAN
via Wikimedia Commons; Morrissey and
Ramsey-Musolf, arXiv:1206.2942

⬇︎ ?

[Here: $Z_2$-symmetric xSM points from arXiv:1910.13125]

strong transitions

is released as latent heat)

- Mark Hindmarsh, Kari Rummukainen
**Oli Gould**, Asier Lopez-Eiguren,*Tuomas Tenkanen**Daniel Cutting*, Jani Dahl, Lauri Niemi**Anna Kormu****Satumaaria Sukuvaara**,**Essi Vilhonen**

- Next few years:
**GW Cosmology for LISA**- Cutting-edge simulations of the early universe
- Microscale (Monte Carlo) to macroscale (hydro)
- Dark and visible sectors

- After that:
**The Energy and Gravity Frontiers**- Electroweak phase transition and
beyond:

CEPC (2030-), ILC (2035-) - Finnish role in European GW missions:

Einstein Telescope (2030-), LISA (2034-) - Complementarity between GW and colliders

- Electroweak phase transition and
beyond: