First Search for Nontensorial Gravitational Waves from Known Pulsars.

Area of Science:

• Astronomy and Astrophysics
• Gravitational Wave Physics
• Fundamental Physics

Background:

• General relativity predicts only two polarizations (plus and cross) for gravitational waves.
• Alternative metric theories of gravity may allow for additional polarization modes.
• Gravitational wave astronomy is a rapidly developing field with advanced detectors.

Purpose of the Study:

• To perform the first directed search for nontensorial gravitational waves.
• To investigate the existence of scalar and vector gravitational wave polarizations.
• To constrain alternative theories of gravity by setting new upper limits.

Main Methods:

• Analysis of data from the first advanced LIGO detector observing run.
• Targeted search for continuous gravitational wave signals at twice the rotational frequency of 200 known pulsars.
• Development of methods sensitive to scalar, vector, and tensor polarizations.

Main Results:

• No statistically significant evidence for nontensorial gravitational waves was detected.
• The first upper limits on scalar and vector gravitational wave strains were established.
• These limits are comparable in magnitude to existing upper limits for tensor strain.

Conclusions:

• The absence of detected nontensorial waves places constraints on certain alternative theories of gravity.
• The established upper limits provide valuable data for future gravitational wave research.
• This search expands the scope of gravitational wave detection beyond standard predictions.