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Maximum Redshift of Gravitational Wave Merger Events
Savvas M Koushiappas1, Abraham Loeb2
1Department of Physics, Brown University, 182 Hope St., Providence, Rhode Island 02912, USA and Institute for Theory and Computation, Harvard University, 60 Garden Street, Cambridge, Massachusetts 02138, USA.
Physical Review Letters
|December 30, 2017
Summary
Future gravitational wave detectors may find events beyond electromagnetic reach. An event rate over one per year at redshift z≥40 implies non-Gaussian primordial density fluctuations or primordial black holes, distinguishable by merger rate distribution.
Area of Science:
- Cosmology
- Astrophysics
- Gravitational Wave Astronomy
Background:
- Future gravitational wave detectors will achieve unprecedented sensitivity.
- This sensitivity will extend to cosmological distances, surpassing electromagnetic detection capabilities.
Purpose of the Study:
- To investigate the implications of detecting gravitational wave events at high redshifts (z≥40).
- To determine potential origins of such events, distinguishing between cosmological and astrophysical sources.
Main Methods:
- Analysis of expected event rates for future gravitational wave detectors.
- Modeling of primordial density fluctuation distributions.
- Consideration of primordial black hole merger rates.
Main Results:
- An observed event rate exceeding one per year at z≥40 strongly suggests non-Gaussian primordial density fluctuations.
- Alternatively, such an event rate could indicate the presence of primordial black holes.
- The redshift distribution of merger rates can differentiate between these scenarios.
Conclusions:
- High-redshift gravitational wave event rates provide crucial cosmological information.
- These observations can probe fundamental physics, including the nature of early universe fluctuations and compact object formation.
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