The black hole symphony: probing new physics using gravitational waves

2008 ◽  
Vol 366 (1884) ◽  
pp. 4365-4379 ◽  
Author(s):  
Jonathan R Gair
Keyword(s):  
Black Holes ◽  
Gravitational Waves ◽  
Direct Detection ◽  
New Physics ◽  
Relativity Theory ◽  
New Generation ◽  
Laser Interferometers ◽  
Near Future ◽  
First Time ◽  
The Universe

The next decade will very likely see the birth of a new field of astronomy as we become able to directly detect gravitational waves (GWs) for the first time. The existence of GWs is one of the key predictions of Einstein's theory of general relativity, but they have eluded direct detection for the last century. This will change thanks to a new generation of laser interferometers that are already in operation or which are planned for the near future. GW observations will allow us to probe some of the most exotic and energetic events in the Universe, the mergers of black holes. We will obtain information about the systems to a precision unprecedented in astronomy, and this will revolutionize our understanding of compact astrophysical systems. Moreover, if any of the assumptions of relativity theory are incorrect, this will lead to subtle, but potentially detectable, differences in the emitted GWs. Our observations will thus provide very precise verifications of the theory in an as yet untested regime. In this paper, I will discuss what GW observations could tell us about known and (potentially) unknown physics.

Beyond the Schwarzschild Metric

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Waves ◽  
Test Particle ◽  
Direct Detection ◽  
Relativistic Effects ◽  
Big Bang ◽  
Clusters Of Galaxies ◽  
General Relativistic ◽  
The Universe

General relativity explains much more than the spacetime around static spherical masses.We briefly assess general relativity in the larger context of physical theories, then explore various general relativistic effects that have no Newtonian analog. First, source massmotion gives rise to gravitomagnetic effects on test particles.These effects also depend on the velocity of the test particle, which has substantial implications for orbits around black holes to be further explored in Chapter 20. Second, any changes in the sourcemass ripple outward as gravitational waves, and we tell the century‐long story from the prediction of gravitational waves to their first direct detection in 2015. Third, the deflection of light by galaxies and clusters of galaxies allows us to map the amount and distribution of mass in the universe in astonishing detail. Finally, general relativity enables modeling the universe as a whole, and we explore the resulting Big Bang cosmology.

A Tale of Two Infinities

2021 ◽  
Author(s):  
Gianfranco Bertone
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Gravitational Waves ◽  
Direct Detection ◽  
Traditional Approach ◽  
Fundamental Physics ◽  
Modern Cosmology ◽  
Nobel Prize In Physics ◽  
The Universe ◽  
Modern Astronomy

The spectacular advances of modern astronomy have opened our horizon on an unexpected cosmos: a dark, mysterious Universe, populated by enigmatic entities we know very little about, like black holes, or nothing at all, like dark matter and dark energy. In this book, I discuss how the rise of a new discipline dubbed multimessenger astronomy is bringing about a revolution in our understanding of the cosmos, by combining the traditional approach based on the observation of light from celestial objects, with a new one based on other ‘messengers’—such as gravitational waves, neutrinos, and cosmic rays—that carry information from otherwise inaccessible corners of the Universe. Much has been written about the extraordinary potential of this new discipline, since the 2017 Nobel Prize in physics was awarded for the direct detection of gravitational waves. But here I will take a different angle and explore how gravitational waves and other messengers might help us break the stalemate that has been plaguing fundamental physics for four decades, and to consolidate the foundations of modern cosmology.

Gravitational waves and the (quantum) nature of the primordial seed

2014 ◽  
Vol 23 (12) ◽  
pp. 1441005 ◽  
Author(s):  
Rafael A. Porto
Keyword(s):  
Gravitational Waves ◽  
Large Scale ◽  
Direct Detection ◽  
Indirect Measurement ◽  
Effective Field ◽  
Quantum Vacuum ◽  
Vacuum Fluctuations ◽  
Early Universe Cosmology ◽  
New Generation ◽  
The Universe

At first glance, the (indirect) measurement of primordial tensor modes by the BICEP2 Collaboration supports an inflationary paradigm for early universe cosmology together with quantum vacuum fluctuations (aka gravitons) as the origin of the spectrum. In this paper, we argue the observed signal may instead be a signature of semiclassical sources of perturbations during inflation. In this scenario, despite a large tensor-to-scalar ratio r ≃ 0.2, it may be possible to write an effective field theory (EFT) of a rolling scalar field without super-Planckian excursions. If the results from BICEP2 withstand further scrutiny, measurements of primordial non-Gaussianity with large scale structure surveys, and direct detection of gravitational waves (GWs) with the new generation of observatories, will be of paramount importance to elucidate the (quantum) origin of structure in the universe.

Dark Energy

2021 ◽  
pp. 79-88
Author(s):  
Gianfranco Bertone
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Energy ◽  
Gravitational Waves ◽  
Quantum Physics ◽  
New Physics ◽  
The Universe

I discuss here black holes, extreme astronomical objects that swallow all forms of matter and radiation surrounding them, and leave behind, as physicist John A. Wheeler said, only their ‘gravitational aura’. These endlessly fascinating objects are the gates where gravity meets quantum physics. Since the pioneering work of scientists like S. Hawking, black holes have become ‘theoretical laboratories’ to explore new physics theories. I discuss how the discovery of gravitational waves from black holes, and the first image of a black hole revealed in 2019, have transformed the study of black holes, and may soon lead to new ground-breaking discoveries. The Universe will disappear. Slowly, it will grow dimmer and dimmer, until it disappears completely.

scholarly journals The gravitational-wave physics

2017 ◽  
Vol 4 (5) ◽  
pp. 687-706 ◽  
Author(s):  
Rong-Gen Cai ◽  
Zhoujian Cao ◽  
Zong-Kuan Guo ◽  
Shao-Jiang Wang ◽  
Tao Yang
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Laser Interferometer ◽  
Direct Detection ◽  
Fundamental Physics ◽  
First Order ◽  
Compact Binary ◽  
First Order Phase Transition ◽  
First Order Phase ◽  
The Universe

Abstract The direct detection of gravitational wave by Laser Interferometer Gravitational-Wave Observatory indicates the coming of the era of gravitational-wave astronomy and gravitational-wave cosmology. It is expected that more and more gravitational-wave events will be detected by currently existing and planned gravitational-wave detectors. The gravitational waves open a new window to explore the Universe and various mysteries will be disclosed through the gravitational-wave detection, combined with other cosmological probes. The gravitational-wave physics is not only related to gravitation theory, but also is closely tied to fundamental physics, cosmology and astrophysics. In this review article, three kinds of sources of gravitational waves and relevant physics will be discussed, namely gravitational waves produced during the inflation and preheating phases of the Universe, the gravitational waves produced during the first-order phase transition as the Universe cools down and the gravitational waves from the three phases: inspiral, merger and ringdown of a compact binary system, respectively. We will also discuss the gravitational waves as a standard siren to explore the evolution of the Universe.

The Biggest Ears in the Sky: LIGO

2020 ◽  
pp. 108-136
Author(s):  
John W. Moffat
Keyword(s):  
Black Holes ◽  
Gravitational Waves ◽  
Nobel Prize ◽  
Executive Director ◽  
Numerical Relativity ◽  
Washington State ◽  
Wave Form ◽  
Press Conference ◽  
The Masses ◽  
First Time

At a press conference on February 11, 2016, David Reitz, LIGO Executive Director, announced, “We did it!” They detected gravitational waves for the first time. Both LIGO sites, in Washington state and Louisiana, registered the incoming gravitational waves from two black holes colliding and merging far away. Over the following months, more mergers were detected. Gravitational waves are caused by the acceleration of a massive object, which stretches and compresses spacetime in a wave-like motion that is incredibly small and difficult to detect. Numerical relativity research over decades has produced over a quarter of a million template solutions of Einstein’s equations. The best template fit to the wave form data identifies the masses and spins of the two merging black holes. Much of this chapter describes the technology of the LIGO apparatus. On October 3, 2017, Barish, Thorne, and Weiss, the founders of LIGO, received the Nobel Prize for Physics.

scholarly journals Magnetism in the Early Universe

2018 ◽  
Vol 14 (A30) ◽  
pp. 295-298
Author(s):  
Tina Kahniashvili ◽  
Axel Brandenburg ◽  
Arthur Kosowsky ◽  
Sayan Mandal ◽  
Alberto Roper Pol
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Gravitational Waves ◽  
Early Universe ◽  
Large Scale ◽  
Direct Detection ◽  
Correlation Lengths ◽  
Cosmological Scenario ◽  
Expansion Of The Universe ◽  
The Universe

AbstractBlazar observations point toward the possible presence of magnetic fields over intergalactic scales of the order of up to ∼1 Mpc, with strengths of at least ∼10−16 G. Understanding the origin of these large-scale magnetic fields is a challenge for modern astrophysics. Here we discuss the cosmological scenario, focussing on the following questions: (i) How and when was this magnetic field generated? (ii) How does it evolve during the expansion of the universe? (iii) Are the amplitude and statistical properties of this field such that they can explain the strengths and correlation lengths of observed magnetic fields? We also discuss the possibility of observing primordial turbulence through direct detection of stochastic gravitational waves in the mHz range accessible to LISA.

scholarly journals Testing massive-field modifications of gravity via gravitational waves

2019 ◽  
Vol 2019 (10) ◽  
Author(s):  
Kei Yamada ◽  
Tatsuya Narikawa ◽  
Takahiro Tanaka
Keyword(s):  
Gravitational Waves ◽  
Direct Detection ◽  
Coupling Parameter ◽  
Open Data ◽  
Mass Range ◽  
Dipole Radiation ◽  
Binary Black Hole ◽  
Type Coupling ◽  
First Time ◽  
Massive Field

Abstract The direct detection of gravitational waves now provides a new channel for testing gravity theories. Despite that the parametrized post-Einsteinian framework is a powerful tool to quantitatively investigate the effects of modifications to gravity theory, the gravitational waveform in this framework is still extendable. One such extension is to take into account the gradual activation of dipole radiation due to massive fields, which are still only very weakly constrained if their mass $m$ is greater than $10^{-16}$$\,$eV from pulsar observations. Ground-based gravitational-wave detectors (LIGO, Virgo, and KAGRA) are sensitive to this activation in the mass range $10^{-14}$$\,$eV $\lesssim m \lesssim 10^{-13}$$\,$eV. Hence, we discuss a dedicated test for dipole radiation due to a massive field using the LIGO/Virgo collaboration’s open data. In addition, assuming Einstein dilaton Gauss Bonnet (EdGB) type coupling, we combine the results of the analysis of binary black hole events to obtain 90% confidence level constraints on the coupling parameter $\alpha_{\rm EdGB}$ as $\sqrt{\alpha_{\rm EdGB}} \lesssim 2.47$$\,$km for any mass less than $6 \times 10^{-14}$$\,$eV for the first time, including $\sqrt{\alpha_{\rm EdGB}} \lesssim 1.85$$\,$km in the massless limit.

scholarly journals Inferring the population properties of binary black holes from unresolved gravitational waves

2020 ◽  
Vol 496 (3) ◽  
pp. 3281-3290 ◽  
Author(s):  
Rory J E Smith ◽  
Colm Talbot ◽  
Francisco Hernandez Vivanco ◽  
Eric Thrane
Keyword(s):  
Black Holes ◽  
Gravitational Waves ◽  
Monte Carlo Study ◽  
Design Sensitivity ◽  
Spin Distribution ◽  
Binary Black Holes ◽  
Compact Binaries ◽  
Compact Binary ◽  
Binary Mergers ◽  
The Universe

ABSTRACT The vast majority of compact binary mergers in the Universe produce gravitational waves that are too weak to yield unambiguous detections; they are unresolved. We present a method to infer the population properties of compact binaries – such as their merger rates, mass spectrum, and spin distribution – using both resolved and unresolved gravitational waves. By eliminating entirely the distinction between resolved and unresolved signals, we eliminate bias from selection effects. To demonstrate this method, we carry out a Monte Carlo study using an astrophysically motivated population of binary black holes. We show that some population properties of compact binaries are well constrained by unresolved signals after about one week of observation with Advanced LIGO at design sensitivity.

The Direct Detection of Gravitational Waves

2018 ◽  
pp. 106-109
Author(s):  
Alvaro De Rújula
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Gravitational Waves ◽  
Direct Detection ◽  
Space Time ◽  
New Era ◽  
The Third ◽  
Perfect Storm

Gravitational waves emitted by black hole mergers. The first LIGO event: GW150917, the coalescence of two black holes of twenty nine and thirty six solar masses into one of “only” sixty two. The remaining three solar masses were emitted as energy in gravitational waves, a gigantic and perfect storm in the fabric of space-time. This is the dawn of a new era: The opening of the third “window” through which to look at the sky. Yet another triumph of general relativity. How much progress astrophysics has made since my time as a student.

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