An analysis of the LIGO discovery based on introductory physics

Mathur, Harsh; Jones-Smith, Katherine; Lowenstein, Ashton

doi:10.1119/1.4985727

Cited by 23 publications

(42 citation statements)

References 15 publications

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“…The last term is the kinetic energy of the stars, neglecting their spin and internal structure. The power radiated via gravitational waves is [65,66]…”

Section: A Effects Of a New Yukawa Forcementioning

confidence: 99%

Cuckoo’s eggs in neutron stars: can LIGO hear chirps from the dark sector?

Laha

Opferkuch

Shepherd

2018

J. High Energ. Phys.

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We explore in detail the possibility that gravitational wave signals from binary inspirals are affected by a new force that couples only to dark matter particles. We discuss the impact of both the new force acting between the binary partners as well as radiation of the force carrier. We identify numerous constraints on any such scenario, ultimately concluding that observable effects on the dynamics of binary inspirals due to such a force are not possible if the dark matter is accrued during ordinary stellar evolution. Constraints arise from the requirement that the astronomical body be able to collect and bind at small enough radius an adequate number of dark matter particles, from the requirement that the particles thus collected remain bound to neutron stars in the presence of another neutron star, and from the requirement that the theory allows old neutron stars to exist and retain their charge. Thus, we show that any deviation from the predictions of general relativity observed in binary inspirals must be due either to the material properties of the inspiraling objects themselves, such as a tidal deformability, to a true fifth force coupled to baryons, or to a nonstandard production mechanism for the dark matter cores of neutron stars. Viable scenarios of the latter type include production of dark matter in exotic neutron decays, or the formation of compact dark matter objects in the early Universe that later seed star formation or are captured by stars.

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“…The last term is the kinetic energy of the stars, neglecting their spin and internal structure. The power radiated via gravitational waves is [65,66]…”

Section: A Effects Of a New Yukawa Forcementioning

confidence: 99%

Cuckoo’s eggs in neutron stars: can LIGO hear chirps from the dark sector?

Laha

Opferkuch

Shepherd

2018

J. High Energ. Phys.

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“…If we further associate the wave with an energy density ∝ ω 2 h 2 GW (cf. Mathur et al, 2017) and moving with a speed of light, it follows that energy will be emitted at a rate ∝ ω 2 E 2 . Writing the proportionality constant as κ, we have…”

Section: Gravitational-wave Inspiralmentioning

confidence: 99%

Astronomy and the new SI

Saha

2020

PASP

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In 2019 the International System of units (SI) conceptually re-invented itself. This was necessary because quantum-electronic devices had become so precise that the old SI could no longer calibrate them. The new system defines values of fundamental constants (including c, h, k, e but not G) and allows units to be realized from the defined constants through any applicable equation of physics. In this new and more abstract SI, units can take on new guises -for example, the kilogram is at present best implemented as a derived electrical unit. Relevant to astronomy, however, is that several formerly non-SI units, such as electron-volts, light-seconds, and what we may call "gravity seconds" GM/c 3 , can now be interpreted not as themselves units, but as shorthand for volts and seconds being used with particular equations of physics. Moreover, the classical astronomical units have exact and rather convenient equivalents in the new SI: zero AB magnitude amounts to 5 × 10 10 photons m −2 s −1 per logarithmic frequency or wavelength interval, 1 au 500 lightseconds, 1 pc 10 8 light-seconds, while a solar mass 5 gravity-seconds. As a result, the unit conversions ubiquitous in astrophysics can now be eliminated, without introducing other problems, as the old-style SI would have done. We review a variety of astrophysical processes illustrating the simplifications possible with the new-style SI, with special attention to gravitational dynamics, where care is needed to avoid propagating the uncertainty in G. Well-known systems (GPS satellites, GW170817, and the M87 black hole) are used as examples wherever possible.

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“…For best results, we minimize the base and maximize the height of the triangle (within the limits of how far the beam will stay focused) so that the beam arrives as close to normal incidence as possible, and align the beam onto the center of the PZT-driven mirror. The beam then reflects off a beamsplitter into an optical cavity (5). Note that we do not need the other interferometer arm for this experiment, so the transmitted beam can be blocked.…”

Section: Advanced Experiments: Locking the Optical Cavity To Resonmentioning

confidence: 99%

“…We had good results with a Thorlabs Discrete Piezo Stack (Model PK2FQP2, 19.6 lm displacement at 75V, 65 kHz resonance) driven with a 5 V peak-to-peak sine wave, yielding approximately 1.3 lm of motion. The cavity mirror (5) should be swept with a low frequency (%1 Hz) triangle wave such that the cavity passes at least from one bright fringe to the next.…”

Section: Advanced Experiments: Locking the Optical Cavity To Resonmentioning

confidence: 99%

“…However, given the complexity of the LIGO experiment, it is a challenge to break down gravitational-wave and detector physics to an understandable level. Mathur et al have suggested ideas on how to analyze LIGO data by using introductory physics, 5 and Burko has published an introductory lab on the topic. 6 Detailed information on the basic physics of the 2015 binary black hole merger (GW150914), which is suitable for educators and students, can be found in an article published by the LIGO Scientific and VIRGO collaborations.…”

Section: Introductionmentioning

confidence: 99%

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LIGO analogy lab—A set of undergraduate lab experiments to demonstrate some principles of gravitational wave detection

Ugolini

Rafferty

Winter

et al. 2019

American Journal of Physics

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The first direct detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in September 2015 proved their existence, as predicted by Einstein's General Theory of Relativity, and ushered in the era of gravitational-wave interferometry. In this article, we present a set of lab course experiments at different levels of advancement, which give students insight into the basic LIGO operating principle and advanced detection techniques. Starting with methods for folding an optical cavity, we advance to analogy experiments with sound waves that can be detected with a Michelson interferometer with an optical cavity arm. In that experiment, students also learn how the sensitivity of the device can be tuned. In a last step, we show how optical heterodyne detection (the mixing of a signal with a reference oscillator) was used in Initial LIGO. We hope these experiments not only give students an understanding of some LIGO techniques but also awaken a fascination for how unimaginably tiny signals, created by powerful cosmic events a billion years ago or earlier, can be detected today here on Earth.

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An analysis of the LIGO discovery based on introductory physics

Cited by 23 publications

References 15 publications

Cuckoo’s eggs in neutron stars: can LIGO hear chirps from the dark sector?

Cuckoo’s eggs in neutron stars: can LIGO hear chirps from the dark sector?

Astronomy and the new SI

LIGO analogy lab—A set of undergraduate lab experiments to demonstrate some principles of gravitational wave detection

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