The Search for Scalar Polarization Gravitational Wavespeel/SDU_Sophomores/2018... · 2018. 5....
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The Search for Scalar Polarization Gravitational Waves Jacob Grant [email protected] Science, Discovery and The Universe Physics and Computer Science What? Conclusions Limitations How? I want to thank Professor Peter Shawhan for giving me the opportunity to work with him on this project • Gravitational Waves (GW) are ripples in space- time from any moving object. Because space itself is what is moving, objects along the waves path stretch and compress when a GW moves through it (at the speed of light). • The Laser Interferometer GW Observatory (LIGO) has confirmed the existence of a certain type of GW which was predicted by Einstein in 1916: tensor polarization (left image) • My search is for a different type of GW, not predicted by Einstein, but theorized to be created from spherical collapse events such as supernovae: scalar polarization. • There were several limitations and question marks that prevent a definite conclusion. A major limitation is the absence of supporting data from other independent studies to back up my conclusions. The few detection efficiency studies that had been completed arrived at a similar conclusion, but had key differences along the way. One example is the fact that my scalar signal – scalar analysis graph only reaches 70% efficiency while other studies reached 100%. • Another limitation is that my work was done without the help of a supporting team. Because I had to teach myself how to do the analyses, it is possible that I made mistakes. • Another drawback is that this simulation is subject to interfering noise being mistaken for a signal. To combat this problem, the simulation only includes signals with an IFAR (inverse false alarm rate) of 8 years. However, it is possible that some noise was mistaken for a signal in my study, leading to discrepancies with other studies. • After running simulations for both scalar and tensor analyses, and for two, three and four detector networks, I was able to conclude that the scalar analysis is more sensitive than the tensor analysis because it is able to detect lower hrss at the same efficiency. This indicates that in order for LIGO to effectively search for scalar waves, it will need to run a different configuration than it does now. • This result is promising because it indicates that the reason that scalar waves have not been discovered is because the normal tensor analysis is not sensitive enough to detect such waves, not that they don’t exist. • Additionally, I was able to conclude that adding more detectors helps efficiency significantly. As I increased detector networks, both the tensor and scalar analyses base hrss decreased, indicating a higher sensitivity. • Future studies, especially after the construction of the 3 rd and 4 th detectors in India and Japan, should focus on analyzing data through the scalar analysis if scalar waves are to be discovered. • My research was to determine if two detectors are sensitive enough to detect weak scalar gravitational waves in their current configuration or if additional detectors are needed. • To determine the solution, I used Coherent WaveBurst to create efficiency graphs for various simulated detections. This program generated thousands of GW, all with different amplitudes, which I then analyzed to determine if a certain detector configuration was sensitive enough to detect scalar signals. • I analyzed two different detector configurations: scalar signal - scalar analysis and scalar signal – tensor analysis. In addition to varying the configurations, I added additional detectors to determine if the increased sensitivity helped with detection efficiency. • The detection efficiency graphs can be seen below. Having a lower hrss (root sum square amplitude. Ratio of the change in traveling distance of the light beam to the frequency of the wave) than a different configuration indicates that the specific configuration is able to detect smaller amplitudes and is more sensitive. Research Images Interferometry? • To detect GW, LIGO uses interferometry. Each of the two detectors have two perpendicular 4km long arms. A laser is shot and immediately split into two light beams which each travel down one of the 4km arms. At the end of each arm a mirror reflects the light beam; the beam then travels back to the origin. Both light beams recombine at the same time and produce a constructive interference pattern. • However, if a GW passes by, one of the arms will be stretched/compressed and thus one of the light beams will travel a different distance (much less than the width of a proton). When they recombine, a destructive interference pattern will be seen, thus indicating a GW passed through. Tensor Polarization Scalar Polarization Scalar Signal - Scalar Analysis Efficiency for Three Detector Network Scalar Signal - Tensor Analysis Efficiency for Three Detector Network Comparing the SGW and TSGW efficiencies at 50 percent hrss Ligo.Caltech.edu
Transcript of The Search for Scalar Polarization Gravitational Wavespeel/SDU_Sophomores/2018... · 2018. 5....
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The Search for Scalar PolarizationGravitational Waves
Jacob [email protected]
Science, Discovery and The UniversePhysics and Computer Science
What?
ConclusionsLimitations
How?
I want to thank Professor Peter Shawhan for giving me the opportunity to work with him on this project
• Gravitational Waves (GW) are ripples in space-time from any moving object. Because space itself is what is moving, objects along the waves path stretch and compress when a GW moves through it (at the speed of light).
• The Laser Interferometer GW Observatory (LIGO) has confirmed the existence of a certain type of GW which was predicted by Einstein in 1916: tensor polarization (left image)
• My search is for a different type of GW, not predicted by Einstein, but theorized to be created from spherical collapse events such as supernovae: scalar polarization.
• There were several limitations and question marks that prevent a definite conclusion. A major limitation is the absence of supporting data from other independent studies to back up my conclusions. The few detection efficiency studies that had been completed arrived at a similar conclusion, but had key differences along the way. One example is the fact that my scalar signal – scalar analysis graph only reaches 70% efficiency while other studies reached 100%.
• Another limitation is that my work was done without the help of a supporting team. Because I had to teach myself how to do the analyses, it is possible that I made mistakes.
• Another drawback is that this simulation is subject to interfering noise being mistaken for a signal. To combat this problem, the simulation only includes signals with an IFAR (inverse false alarm rate) of 8 years. However, it is possible that some noise was mistaken for a signal in my study, leading to discrepancies with other studies.
• After running simulations for both scalar and tensor analyses, and for two, three and four detector networks, I was able to conclude that the scalar analysis is more sensitive than the tensor analysis because it is able to detect lower hrss at the same efficiency. This indicates that in order for LIGO to effectively search for scalar waves, it will need to run a different configuration than it does now.
• This result is promising because it indicates that the reason that scalar waves have not been discovered is because the normal tensor analysis is not sensitive enough to detect such waves, not that they don’t exist.
• Additionally, I was able to conclude that adding more detectors helps efficiency significantly. As I increased detector networks, both the tensor and scalar analyses base hrss decreased, indicating a higher sensitivity.
• Future studies, especially after the construction of the 3rd and 4th detectors in India and Japan, should focus on analyzing data through the scalar analysis if scalar waves are to be discovered.
• My research was to determine if two detectors are sensitive enough to detect weak scalar gravitational waves in their current configuration or if additional detectors are needed.
• To determine the solution, I used Coherent WaveBurst to create efficiency graphs for various simulated detections. This program generated thousands of GW, all with different amplitudes, which I then analyzed to determine if a certain detector configuration was sensitive enough to detect scalar signals.
• I analyzed two different detector configurations: scalar signal - scalar analysis and scalar signal –tensor analysis. In addition to varying the configurations, I added additional detectors to determine if the increased sensitivity helped with detection efficiency.
• The detection efficiency graphs can be seen below. Having a lower hrss (root sum square amplitude. Ratio of the change in traveling distance of the light beam to the frequency of the wave) than a different configuration indicates that the specific configuration is able to detect smaller amplitudes and is more sensitive.
Research Images
Interferometry?• To detect GW, LIGO uses interferometry. Each of
the two detectors have two perpendicular 4km long arms. A laser is shot and immediately split into two light beams which each travel down one of the 4km arms. At the end of each arm a mirror reflects the light beam; the beam then travels back to the origin. Both light beams recombine at the same time and produce a constructive interference pattern.
• However, if a GW passes by, one of the arms will be stretched/compressed and thus one of the light beams will travel a different distance (much less than the width of a proton). When they recombine, a destructive interference pattern will be seen, thus indicating a GW passed through.
Tensor Polarization
Scalar Polarization
Scalar Signal - Scalar Analysis Efficiency for Three Detector Network
Scalar Signal - Tensor Analysis Efficiency for Three Detector Network
Comparing the SGW and TSGW efficiencies at 50 percent hrss
Ligo.Caltech.edu
