Cosmic Explorer: The U.S. Contribution to Gravitational-Wave Astronomy beyond LIGO (1907.04833v1)

Abstract: This white paper describes the research and development needed over the next decade to realize "Cosmic Explorer," the U.S. node of a future third-generation detector network that will be capable of observing and characterizing compact gravitational-wave sources to cosmological redshifts.

• The paper outlines a two-stage design that boosts gravitational-wave sensitivity by an order of magnitude over Advanced LIGO.
• It employs innovative cryogenic systems and new mirror substrates to significantly reduce quantum and thermal noise.
• It enables multimessenger astronomy by integrating gravitational and electromagnetic data to probe neutron star mergers and black hole evolution.

Overview of Cosmic Explorer: Advancements in Gravitational-Wave Astronomy

The research paper on Cosmic Explorer outlines the initiative aimed at advancing gravitational-wave astronomy through the development of a next-generation observatory. This endeavor represents the U.S. contribution to a global network of third-generation gravitational-wave detectors, following the National Science Foundation’s (NSF) Advanced LIGO and Virgo facilities. The Cosmic Explorer project is designed in two stages to expand the detection capabilities beyond existing observatories, enabling significantly deeper insights into cosmic phenomena.

Cosmic Explorer will enhance gravitational-wave detection sensitivity by an order of magnitude over Advanced LIGO, operating with 40km arm lengths optimized for detecting gravitational waves over a 5–4000Hz spectrum. The two-stage design process involves scaling Advanced LIGO technologies into Stage 1 and later implementing more advanced technologies in Stage 2. Stage 2's advancement includes cryogenic systems and new mirror substrates to decrease quantum and thermal noise, with eventual commencement of observations planned for the 2040s.

Key Scientific Objectives

The Cosmic Explorer project aims to address several pivotal scientific inquiries:

1. Nature of Dense Matter: By capturing neutron star mergers with increased precision, the project aims to elucidate the cold, dense nuclear equation of state that rules neutron-rich matter.
2. Multimessenger Astronomy: The integration of gravitational-wave data with electromagnetic observations facilitates a holistic investigation of cosmic events, particularly mergers involving neutron stars and black holes.
3. Cosmic Black Hole Evolution: By observing stellar-mass black holes up to redshifts of approximately 20, Cosmic Explorer will detail the evolution of black holes and correlate it with cosmic time.
4. Cosmological Probing: The ability to measure cosmological parameters independent of electromagnetic observations could revolutionize understanding of the universe’s expansion history.
5. Fundamental Physics: Testing the limits of general relativity and exploring the characteristic mergers of compact objects comprise another key objective, potentially revealing new physics.

Theoretical and Practical Implications

The successful realization of Cosmic Explorer would vastly increase the count of gravitational-wave detections, providing millions of events per year, which would be instrumental for complementary studies in both gravitational and electromagnetic contexts. It would refine our comprehension of high-energy astrophysical processes and offer a new lens to observe the cosmos, fostering potential breakthroughs in understanding the fundamental laws governing the universe.

Speculation on Future Developments

The execution of Cosmic Explorer is anticipated to stimulate a new era of gravitational-wave astronomy, aligning the efforts globally among third-generation observatories such as the Einstein Telescope. This will lead to unprecedented precision in localizing cosmic events, allowing for more detailed investigations of the regions of space-time producing gravitational waves. In turn, this will likely inspire advancements in associated technology domains like cryogenics and vacuum systems, fueling broad scientific and technological progress.

Conclusion

This white paper outlines a robust path forward for gravitational-wave astronomy through Cosmic Explorer. It highlights the necessity of progressive technological innovations accompanied by substantial investments in research and infrastructure development. By broadening our detection capabilities through an international collaborative network, Cosmic Explorer promises to deepen our understanding of the universe's most profound mechanics and mysteries, marking a significant milestone in astrophysical research.