Masha Baryakhtar

GRAVITATIONAL WAVES: FROM DETECTION TO NEW PHYSICS SEARCHES

Masha Baryakhtar

New York University

Lecture 1 June 29. 2020 1.3 Billion Years Ago

two ~30 solar mass black holes merged and produced a burst of gravitational wave radiation 2 1.3 Billion Years Ago

Animation created by SXS, the Simulating eXtreme Spacetimes (SXS) project (http://www.black-holes.org) Superradiance and Black Holes

The colored surface is the space of our universe, as viewed from a hypothetical, ﬂat, higher-dimensional universe, in which our own universe is embedded. Our universe looks like a warped two-dimensional sheet because one of its three space dimensions has been removed. Around each black hole, space bends downward in a funnel shape, a warping produced by the black hole's huge mass. 3 September 14, 2015

the LIGO detectors observe gravitational waves for the ﬁrst time 4 September 14, 2015

On September 14, 2015, LIGO observed gravitational waves from the merger of two black holes, each about 30 times the mass of our sun. The incredibly powerful event, which released 50 times more energy than all the stars in the observable universe, lasted only fractions of a second.

Caltech/MIT/LIGO Lab the LIGO detectors observe gravitational waves for the ﬁrst time 5 September 14, 2015 The Sound of Two Black Holes Colliding Superradiance and Black Holes

Audio Credit: Caltech/MIT/LIGO Lab the LIGO detectors observe gravitational waves for the ﬁrst time 6 Today

watching the announcement of GW discovery at Perimeter Institute what have we learned and where do we go from here? 7 Observation of Gravitational Waves

• An amazing scientiﬁc and technological achievement

• Conﬁrms what we predicted about strong gravity and are learning

new things about the most extreme objects

• New window on the universe and a new tool for new physics

searches

8 4 kilometer long Michelson interferometers, An amazing scientiﬁc measuring displacements at better than one and technological part in 10^21 achievement Powerful and complex laser, optics, and isolation systems and a team of over 1000 people New Types of BHs, Binaries, Sources of Elements

Since the ﬁrst detection,

>dozen BH BH

mergers, two NS NS

mergers, and a recent

BH-? merger have been

detected

11 New Types of BHs, Binaries, Sources of Elements

The ﬁrst NSNS merger was followed up by many EM observations

Learning about EoS of neutron stars and production of heavy element abundances

12 Just the beginning

• Observatories around the world planned and under construction

13 Just the beginning

• Sensitivity improvements planned over the next decade

• Observatories around the world planned and under construction

14 3rd Generation Detectors Planned to Improve Sensitivity

• 10 to 40 km long • Quantum enhanced • Novel mirrors

N. Mavalvala 2020 15 3rd Generation Detectors Planned to Improve Sensitivity

• 10 to 40 km long • Binary neutron stars out to z ≈ 6 • Quantum enhanced • Binary black holes out to z ≈ 10 • Novel mirrors

Evan Hall, 2019

will see ~all mergers in the N. Mavalvala 2020 observable Universe! 16 A huge range of science opportunities

S. Vitale, 2019 N. Mavalvala 2020 17 A wide spectrum of frequencies to explore

Kip Thorne / Walter Issacson interview

LISA

18 Observation of Gravitational Waves

• An amazing scientiﬁc and technological achievement

• Conﬁrms what we predicted about strong gravity and are learning

new things about the most extreme objects

• New window on the universe and a new tool for new physics

searches

19 Using Tools of Gravitational Wave Astronomy To Look for Dark Matter (Tomorrow)

Atom interferometry

Pulsar Timing Array, artists conception

Image credit: David J. Champion Paul Hamilton UCBerkeley

20 Gravitational Wave Signals from Axions and Dark Photons (Thursday)

Numerical GR simulation by Will East

LIGO is searching for signs of new particles around rotating black holes 21 Gravitational Waves from the Local Universe

• A brief history from doubt to detection

• How to produce and detect a gravitational wave

• Signals and noise — why is detection so difﬁcult?

22 Gravitational Waves:

Electromagnetic waves: displacement of charged particles

Gravitational waves: displacement of all matter

• Maxwell’s1865 “The Dynamical Theory of the Electromagnetic Field” (where he deduced that electromagnetic waves travel at light speed): “After tracing to the action of the surrounding medium both the magnetic and the electric attractions and repulsions [oscillations]…we are naturally led to inquire whether the attraction of gravitation, which follows the same law of the distance, is not also traceable to the action of a surrounding medium.” 23 Gravitational Waves: Einstein’s untestable prediction

• Einstein completes theory of general relativity in 1915 and predicts gravitational waves in 1916, but does not think they can ever be observed. In 1918, he computes the energy lost to gravitational waves in a system.

• Twenty years later, he is still not sure whether gravitational waves are physical or a coordinate artifact; in 1936 he writes to Max Born:

Together with a young collaborator, I arrived at the interesting result that gravitational waves do not exist, though they had been assumed a certainty to the ﬁrst approximation. This shows that the non-linear general relativistic ﬁeld equations can tell us more or, rather, limit us more than we have believed up to now.

• The Physical Review received Einstein’s submission on 1 June 1936 and had referree comments which did not suit Einstein.

Dear Sir,

We (Mr. Rosen and I) had sent you our manuscript for publication and had not authorized you to show it to specialists before it is printed. I see no reason to address the—in any case erroneous— comments of your anonymous expert. On the basis of this incident I prefer to publish the paper elsewhere

P.S. Mr. Rosen, who has left for the Soviet Union, has authorized me to represent him in this matter. 24 Gravitational Waves: Einstein’s untestable prediction

• Twenty years later, he is still not sure whether gravitational waves are physical or a coordinate artifact; in 1936 he writes to Max Born:

• The Physical Review received Einstein’s submission on 1 June 1936 and had referree comments which did not suit Einstein.

Dear Sir,

P.S. Mr. Rosen, who has left for the Soviet Union, has authorized me to represent him in this matter. 25 Gravitational Waves: Einstein’s untestable prediction

• Twenty years later, he is still not sure whether gravitational waves are physical or a coordinate artifact; in 1936 he writes to Max Born:

• The Physical Review received Einstein’s submission on 1 June 1936 and had referree comments which did not suit Einstein.

Dear Sir,

P.S. Mr. Rosen, who has left for the Soviet Union, has authorized me to represent him in this matter. physicstoday.scitation.org/doi/10.1063/1.2117822 26 Gravitational Waves: ﬁnally physical

• At 1957 Chapel Hill Conference, Felix Pirani presented a calculation of the relative acceleration of initially mutually static test particles that encounter a sinusoidal gravitational plane wave.

• During the questions with his advisor Bondi they came up with the idea of connecting the two nearby masses with a dashpot or a spring thus absorbing energy from the wave.

• Bondi publishes the ‘sticky bead argument’ in Nature. Weber and Wheeler publish ‘Reality of cylindrical waves of Einstein and Rosen’ where they state ‘the disturbance in question is real and not removable by any change of coordinate system’, citing original argument 27 Gravitational Waves: ﬁrst experimental efforts

• Joe Weber is at Pirani’s talk and decides that since the gravitational waves are physical, he can detect them, publishing several papers with Wheeler on the topic

• In analogy to the masses connected by a spring, Weber designs the resonant aluminum bar

• Starting in 1969, Weber announces coincident detections of GWs. Follow-up experiments failed to conﬁrm the detections.

• Weber bars are still used search for broadband gravitational waves at high frequencies (~kHz). Major limitation is a narrow frequency range.

• One of the most recently built spherical detectors is the Mario Schenberg gravitational-wave detector, which is now at the National Institute for Space Research (INPE) in Brazil. The sphere is around 65 centimeters in diameter and weighs around 1150 kilograms.

28 Gravitational Waves: ﬁrst experimental efforts

• Joe Weber is at Pirani’s talk and decides that since the gravitational waves are physical, he can detect them, publishing several papers with Wheeler on the topic

• In analogy to the masses connected by a spring, Weber designs the resonant aluminum bar

• Starting in 1969, Weber announces coincident detections of GWs. Follow-up experiments failed to conﬁrm the detections.

• Weber bars are still used search for broadband gravitational waves at high frequencies (~kHz). Major limitation is a narrow frequency range.

AIP Emilio Segrè Visual Archives 29 Gravitational Waves: ﬁrst experimental efforts

• Joe Weber is at Pirani’s talk and decides that since the gravitational waves are physical, he can detect them, publishing several papers with Wheeler on the topic

• In analogy to the masses connected by a spring, Weber designs the resonant aluminum bar

• Starting in 1969, Weber announces coincident detections of GWs. Follow-up experiments failed to conﬁrm the detections.

• Weber bars are still used search for broadband gravitational waves at high frequencies (~kHz). Major limitation is a narrow frequency range.

AIP Emilio Segrè Visual Archives 30 Gravitational Waves: a new direction

• Laser interferometers ﬁrst proposed in 1962 by Gertsenshtein and Pustovoit published in Russian (Zh. Eksp. Teor. Fiz., vol. 43, p. 605, 1962) and in English translation (Sov. Phys. JETP, vol. 16, p. 433, 1963), describing how instruments called interferometers could be used to detect gravitational waves

• Rainer Weiss proposes laser interferometer to detect GWs, ‘Electromagnetically Coupled Broadband Gravitational Antenna’ (MIT report). Includes detailed analysis of detector and noise sources

• “It is assumed that an observer, by the use of light signals or otherwise, determine the coordinates of a neighboring particle in his local Cartesian coordinate system.” -Pirani

31 Gravitational Waves: indirect observation In the meantime…

• Hulse and Taylor discovery the ﬁrst pulsar in a neutron star binary system, 1975

• Orbital decay of the Hulse and Taylor pulsar matches GR prediction, 1980

32 Gravitational Waves: a new direction

• Late 70s: Munich group starts (1975) construction of 3m laser interferometer prototype. Drever, in Glasgow, starts similar research (1977).

• 1992: Weiss, Drever and Thorne found LIGO (Laser Interferometer Gravitational Wave Observatory) as a National Science Foundation projec

• 1999-2010 Initial LIGO in operation, reaching design sensitivity in 2006, Virgo joins collaboration

• 2011 - 2014 Advanced LIGO installation and testing

• Sept 14, 2015 Advanced LIGO detects gravitational waves from collision of two black holes Gravitational Waves: a new direction

• Late 70s: Munich group starts (1975) construction of 3m laser interferometer prototype. Drever, in Glasgow, starts similar research (1977).

• 1992: Weiss, Drever and Thorne found LIGO (Laser Interferometer Gravitational Wave Observatory) as a National Science Foundation projec

• 1999-2010 Initial LIGO in operation, reaching design sensitivity in 2006, Virgo joins collaboration

• 2011 - 2014 Advanced LIGO installation and testing

• Sept 14, 2015 Advanced LIGO detects gravitational one hundred years after GR formulated and waves from collision of two nearly ﬁfty years after ﬁrst experiments! black holes 34 Outline

• A brief history from doubt to detection

• Generation and signals

• Signals and noise — why is detection so hard?

35 and where I am a fellow since January 2015; the University of Geneva (UNIGE, Geneva), which I visited for 4 months during my PhD and where I did my second postdoctoral position during 2 years; the University of Helsinki (HU/HIP, Helsinki), where I did my first postdoctoral position during 2 years; the University of Columbia in New York (Columbia U., NYC), which I visited for 3.5 months in fall 2014; and finally the Imperial College in London and the University of Sussex in Brighton, UK, both of which I visit regularly (few times a year) since 2010. Of course, I also have strong links to the Instituto de Fisica Teorica in the Autonoma University of Madrid, where I did my PhD. My large network of international collaborators and contacts is an important achievement in my career, and I am sure that this will be of great benefit for the group. Currently, I maintain the following international collaborations: i) Imperial College (London, Great Britain), where I work regularly with Prof. Arttu Rajantie; ii) Sussex University (Brigthon, Great Britain), where I work with with Prof. Mark Hindmarsh and faculty member Dr. Chris Byrnes; iii) Columbia University (New York City, US), where thanks to an International Short Visit grant I obtained from the Swiss National Science Foundation, I initiated a collaboration with Prof. Lam Hui; iv) EPFL (Ecole Polytechnique Federale de Lausanne), Switzerland, where I am currently doing a long term project with Prof. M. Shaposhnikov; v) Geneva University (Geneva, Switzerland), where I regularly collaborate with Prof. Ruth Durrer and Prof. Antonio. W. Riotto, and vi) IFAE (Baercelona, Spain), where I have recently started a long term collaboration with Prof. J. R. Espinosa. My large network of international collaborators and contacts is an important achievement in my career, and I am sure that this will be of great benefit for the group.

References

[01] J. Garcia-Bellido and D. G. Figueroa, Phys. Rev. Lett. 98 (2007) 061302 [astro-ph/0701014] [02] J. Garcia-Bellido, D. G. Figueroa and A. Sastre, PRD 77 (2008) 043517 [arXiv:0707.0839 [hep-ph]] [03] D. G. Figueroa, L. Verde and R. Jimenez, JCAP 0810 (2008) 038 [arXiv:0807.0039 [astro-ph]] [04] J. Garcia-Bellido, D. G. Figueroa, and J. Rubio, PRD 79 (2009) 063531 [arXiv:0812.4624 [hep-ph]] [05] E. Fenu, D. G. Figueroa, R. Durrer, J. Ga-Bellido, JCAP 0910 (2009) 005 [arXiv:0908.0425] [06] D. G. Figueroa, AIP Conf. Proc. 1241:578-587, 2010 [arXiv:0911.1465 [hep-ph]] [07] J. Ga-Bellido, R. Durrer, E. Fenu, D. G. Figueroa and M. Kunz, PLB 695 (2011) 26 [arXiv:1003.0299] [08] D. G. Figueroa, R. R. Caldwell and M. Kamionkowski, PRD 81 (2010) 123504 [arXiv:1003.0672] [09] J-F. Dufaux, D. G. Figueroa and J. Ga-Bellido, PRD 82 (2010) 083518 [arXiv:1006.0217] Gravitational[10] Wave K. Enqvist, Deﬁnition D. G. Figueroa and T. Meriniemi, PRD 86 (2012) 061301 [arXiv:1203.4943] Outline[11] D. G. Figueroa, J. Garcia-Bellido and A. Rajantie, JCAP 1111 (2011) 015 [arXiv:1110.0337] From this morning (Daniel Figueroa) [12] K.(TT Enqvist, gauge: D.6 - G. 4 = Figueroa, 2 d.o.f. ) T. Meriniemi, PRD 15, 061301(R) (2012) [arXiv:1203.4943 [astro-ph.CO]] [13]0 D.µ G. Figueroa,i E. Sefusatti, A. Riotto and F. Vernizzi, JCAP 1208 (2012) 036 [arXiv:1205.2015] 1st approach to GWs [14]h K.=0 Enqvist,,h D.i =0 G., Figueroa,∂jhij =0 and R. N. Lerner, JCAP 1301 (2013) 040 [arXiv:1211.5028 [astro-ph.CO]] Outside • A brief history from doubt[15] to D.detection G. Figueroa, M. Hindmarsh andSource J. Urrestilla, Phys. Rev. Lett. 110 (2013) 101302 [arXiv:1212.5458] µ [16] L. Bethke, D. G. Figueroa and A. Rajantie, Phys. Rev. Lett. 111 (2013) 011301 [arXiv:1304.2657] ∂µ∂ hij =0 Wave Eq. Gravitational Waves ! [17] D. G. Figueroa and T. Meriniemi, JHEP 1310 (2013) 101 [arXiv:1306.6911] [18] L. Bethke, D. G. Figueroa and A. Rajantie, JCAP 1406 (2014) 047 [arXiv:1309.1148 [astro-ph.CO]] can GW be[19] 'gauged R. Durrer, away’ E. Fenu,? No D. ! G. Figueroa, and M. Kunz, PRD 89, 083512 (2014) [arXiv:1311.3225] • Generation and signals [20] D. G. Figueroa, JHEP 1411 (2014) 145 [arXiv:1402.1345 [astro-ph.CO]] [21] R. Durrer, D. G. Figueroa and M. Kunz, JCAP 1408 (2014) 029 [arXiv:1404.3855 [astro-ph.CO]] [22] B. Audren,∞ D. G. Figueroa and T. Tram, ArXiv note, May 2014 [arXiv:1405.1390 [astro-ph.CO]] h (t, x)= df dnhˆ (f,nˆ)e 2πif(t nˆx) 2 dof = 2 polarizations ab [23] D. G. Figueroa, J.ab G-Bellido,− F.− Torrenti, PRD 92, 083511 (2015) [arXiv:1504.04600 [astro-ph.CO]] [24] D.! G.−∞ Figueroa,! J. G-Bellido,(plane F. wave) Torrenti, PRD 93, 103521 (2016) [arXiv:1602.03085 [astro-ph]] • Signals and noise — whytransverse is detection plane so hard? [25] D. G. Figueroa and C. Byrnes, PLB (2016), in press [arXiv:1604.03905 [astro-ph]] [26] N. Bartolo et al1, JCAP 1612 (2016) no.12, 026 [arXiv:1610.06481 [astro-ph]] h+ hx 0 Transverse- h (f,nˆ)= h (f,nˆ)ϵ(A)(ˆn) = h h 0 Traceless ab A ab ⎛ x − + ⎞ A=+,x 000 (2 dof) ! ⎝ ⎠ 36

1Group Coordinators: D. G. Figueroa & R. Ricciardone

4 GravitationalOutline Wave Deﬁnition From this morning (Daniel Figueroa) (TT gauge: 6 - 4 = 2 d.o.f. ) 0µ i 1st approach to GWs h =0,hi =0, ∂jhij =0 Outside • A brief history from doubt to detection Source µ ∂µ∂ hij =0 Wave Eq. Gravitational Waves !

can GW be 'gauged away’ ? No ! • Generation and signals

• hSignals+ and noise — why is detection so hard?

37 https://www.youtube.com/watch?v=U_hLM1WPDqM https://www.youtube.com/watch?v=EtL9UyRx_Us Gravitational wave emission and detection

• What is the typical amplitude of these GWs?

• How do you detect one? What is the physical effect?

• (see blackboard) 38 Michelson Interferometer

Animation created by T. Pyle, Caltech/MIT/LIGO Lab 39 Outline

• A brief history from doubt to detection

• Generation and signals

• Signals and noise — why is detection so hard?

40 Noise in Gravitational Wave Detectors

Gravitational wave strain L ⇠ L Advanced LIGO

Advanced LIGO and VIRGO already made several discoveries

Goal to reach target sensitivity in the next years Advanced VIRGO 41 Noise in Gravitational Wave Detectors Advanced LIGO sensitivity

Main limiting factors: shot noise and radiation pressure

LIGO-T1800044-v5

42 Noise in Gravitational Wave Detectors

• What are the limiting noise sources?

• Seismic noise, requires passive and active isolation

• Quantum nature of light: shot noise and radiation pressure

• See blackboard 43 Noise in Gravitational Wave Detectors Advanced LIGO sensitivity

LIGO-T1800044-v5