Gravitational Wave Astronomy Using Pulsars: Massive Black Hole Mergers and the Early Universe
Abstract
Gravitational waves are fluctuations in the fabric of spacetime predicted by Einstein's theory of general relativity. Using a collection of millisecond pulsars as high-precision clocks, the nHz band of this radiation is likely to be detected within the next decade. The fundamental questions that will be addressed by these studies are: 1. What is the nature of space and time? We suspect the local spacetime metric is perturbed by the cumulative effect of gravitational waves (GWs) emitted by numerous massive black hole (MBH) binaries. What is the energy density contained in this stochastic background of GWs? 2. How did structure form in the Universe? Detection of GWs in the pulsar timing band will tell us whether MBHs formed through accretion and/or merger events. 3. What is the structure of individual MBH binary systems? Recovering the gravitational waveform from individual systems will give us unprecedented insight. 4. What contribution do cosmic strings make to the GW background (GWB)? The detection of cosmic strings would open a window into the early universe at a time inaccessible via the electromagnetic spectrum. 5. What currently unknown sources of GW exist in the Universe? Every time a new piece of the electromagnetic spectrum has been opened up to observations (e.g. radio, X-rays, and -rays), new and entirely unexpected classes of objects have been discovered. The existence of GWs has already been inferred via the Nobel Prize-winning observations of the orbital decay of the PSR B1913+16 binary system (Hulse and Taylor 1975). While compelling and entirely consistent with general relativity, the behavior of this system offers only indirect evidence for GWs -- the objective for the 21st century is the direct detection and exploitation of GWs as a non-photonic probe of the Universe.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2010
- Accession Number
- ADA520945
Entities
People
- A. Archibald
- Andrea Lommen
- D. Backer
- J. Cordes
- Joseph Lazio
- P. Demorest
- P. Freire
- R. Ferdman
- Z. Arzoumanian
Organizations
- United States Naval Research Laboratory