Tiffany Summerscales

Searches for gravitational waves associated with pulsar glitches using a coherent network algorithm

Pulsar glitches are a potential source of gravitational waves for current and future interferometric gravitational wave detectors. Some pulsar glitch events were observed by radio and x-ray telescopes during the fifth LIGO science run. It is expected that glitches from these same pulsars should also be seen in the future. We carried out Monte Carlo simulations to estimate the sensitivity of possible gravitational wave signals associated with a pulsar glitch using a coherent network analysis method. We show the detection efficiency and evaluate the reconstruction accuracy of gravitational waveforms using a matched filter analysis on the estimated gravitational waveforms from the coherent analysis algorithm.

Monitoring Sco X-1 for the detection of gravitational waves with networks of gravitational wave detectors

Searching for gravitational waves triggered by electromagnetic astronomical observations has several benefits: prior information about the source location enhances detection efficiency, and the use of time coincidence implies analysis of only a small stretch of data which allows sophisticated analysis with high computational costs. During postprocessing, knowledge about the source enables accurate reconstruction of the source parameters, leading to an astrophysical interpretation. In this paper, we present a triggered search pipeline called RIDGE and we demonstrate the search for gravitational waves from Sco X-1, in which X-ray bursts occur frequently, using simulated data. In the analysis, we consider the optimum network combination for Sco X-1.

Proposed method for searches of gravitational waves from PKS 2155-304 and other blazar flares

We propose to search for gravitational waves from PKS 2155-304 as well as other blazars. PKS 2155-304 emitted a long-duration energetic flare in July 2006 with total isotropic equivalent energy released in TeV gamma rays of approximately 1045 ergs. Possible gravitational wave signals associated with this outburst are expected to be seen at the same time as the electromagnetic signal. During this flare, the two LIGO interferometers at Hanford and the GEO detector were in operation and collecting data. For this search we will use the data from multiple gravitational wave detectors. The method we use for this purpose is a coherent network analysis algorithm which is called RIDGE. To estimate the sensitivity of the search, we perform numerical simulations. For a detection probability of 20%, we estimate that this method is sensitive to total isotropic equivalent energy at the source of about 2.5 × 1055 ergs. For this analysis, an end-to-end pipeline has been developed, which takes into account the motion of the source across the sky.

Determination of the angular momentum distribution of supernovae from gravitational wave observations

Significant progress has been made in the development of an international network of gravitational wave detectors, such as TAMA300, LIGO, VIRGO, and GEO600. For these detectors, one of the most promising sources of gravitational waves are core collapse supernovae especially in our galaxy. Recent simulations of core collapse supernovae, rigorously carried out by various groups, show that the features of the waveforms are determined by the rotational profiles of the core, such as the rotation rate and the degree of the differential rotation prior to core-collapse. Specifically, it has been predicted that the sign of the second largest peak in the gravitational wave strain signal is negative if the core rotates cylindrically with strong differential rotation. The sign of the second peak could be a nice indicator that provides us with information about the angular momentum distribution of the core, unseen without gravitational wave signals. Here we present a data analysis procedure aiming at the detection of the second peak using a coherent network analysis and estimate the detection efficiency when a supernova is at the sky location of the galactic center. The simulations showed we were able to determine the sign of the second peak under an idealized condition of a network of gravitational wave detectors if a supernova occurs at the galactic center.