#### Presentation Title

Characterizing Hybrid Gravitational Waves

#### Faculty Mentor

Jocelyn Read

#### Start Date

18-11-2017 10:45 AM

#### End Date

18-11-2017 11:00 AM

#### Location

9-239

#### Session

Physical Sciences 4

#### Type of Presentation

Oral Talk

#### Subject Area

physical_mathematical_sciences

#### Abstract

Currently there are two commonly used methods for producing theoretical gravitational wave models for use in the LIGO Scientific Collaboration. These two methods are called Post-Newtonian (PN) approximations and Numerical Relativity (NR). PN approximations are typically very long duration waveforms (measured in seconds) but develop large inaccuracies as the two bodies inspiral together. NR waves on the other hand are typically very short duration (measured in milliseconds) but do not develop such large inaccuracies. To remove the developing error in the PN, we attach an NR wave onto the end of a PN model to produce a longer, more accurate representation of the true gravitational wave called a hybrid gravitational wave model.

However, the overall accuracy of a hybrid model depends on various systematic parameters defined in the construction process. Here, we examine the effect of varying both PN model and match region in the construction process for time domain numerical binary neutron star waveforms. Both parameters are shown to produce significant changes in LIGO match filter calculations used in wave searches. We also provide hybrid waveform comparisons between commonly used PN model choices from the LIGO Algorithms Library for a given numerical waveform with associated error bounds for match region choices.

#### Summary of research results to be presented

Using match filter correlation tools provided by the LIGO Algorithms Library, hybrids in question were tested for distinguishability by calculating LIGO noise weighted mismatches or matches. We propose the difference in hybridization frequency is a relevant parameter for hybrid error measurements. We investigate the connection between the hybridization frequency difference and hybrid parameters. After marginalizing over match region and PN model, an upper frequency bound for two binary neutron star simulations is provided in accordance with LIGO accuracy standards. PN model comparisons are also made.

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Characterizing Hybrid Gravitational Waves

9-239

Currently there are two commonly used methods for producing theoretical gravitational wave models for use in the LIGO Scientific Collaboration. These two methods are called Post-Newtonian (PN) approximations and Numerical Relativity (NR). PN approximations are typically very long duration waveforms (measured in seconds) but develop large inaccuracies as the two bodies inspiral together. NR waves on the other hand are typically very short duration (measured in milliseconds) but do not develop such large inaccuracies. To remove the developing error in the PN, we attach an NR wave onto the end of a PN model to produce a longer, more accurate representation of the true gravitational wave called a hybrid gravitational wave model.

However, the overall accuracy of a hybrid model depends on various systematic parameters defined in the construction process. Here, we examine the effect of varying both PN model and match region in the construction process for time domain numerical binary neutron star waveforms. Both parameters are shown to produce significant changes in LIGO match filter calculations used in wave searches. We also provide hybrid waveform comparisons between commonly used PN model choices from the LIGO Algorithms Library for a given numerical waveform with associated error bounds for match region choices.