Motivation

1. Radiometer Measurement of a Black Hole Binary Inspiral Hardware Injection Anthony Kremin, Eric Thrane, Tanner Prestegard, ShivarajKandhasamy, VukMandic School of Physics and Astronomy, University of Minnesota LIGO Document Number ????????????? The Stochastic Transient Analysis Multi-Detector Pipeline (STAMP) uses data cross-correlated from spatially separated detectors to search for gravitational-wave candidates. The purpose of STAMP is to detect transient Gravitational-Wave (GW) signals that exist anywhere from a few seconds to hundreds of seconds. These long-transient events differ from shorter transient “chirp” signals, or the stochastic background, investigated by other pipelines. The goal of this analysis is to look at shorter, chirp-like signals using STAMP to determine whether it can offer additional information about such events. By increasing the time resolution of the frequency-time maps used by STAMP, it becomes possible to resolve chirp-like events such as black hole binary inspirals. One black hole inspiral of particular interest is the hardware injection at GPS time of ~968654558s in the LIGO S6 science run. This event, known as the “Big Dog Event,” has been thoroughly investigated by other pipelines, which makes it the perfect candidate to determine whether STAMP can contribute additional information to such analyses. • Initially larger time resolution was thought to be optimal as it would allow for increased resolution of the chirp. • Initially resolution was used, but an insignificant value of .26??? was obtained from the background study. • A greater time resolution of was attempted but the event was not visible in the SNR ft-map. • Greater resolution in frequency was also attempted, with more significant results. References Next Steps Motivation Method Results Conclusions/Viability • Data from the four kilometer Hanford Observatory (H1) and the four kilometer Livingston Observatory (L1) were cross-correlated using STAMP to analyze the Big Dog (BD). • One-second signal to noise (SNR) frequency-time (ft) maps were used to compare the cross-correlated data of the BD with time-shifted cross-correlated maps. • A one second time-shift between the data from H1 and L1 eliminates astrophysical data since the entire duration of the event is less than this value. • A comparison can then be made between the BD and time-shifted data, which act as background estimates. • Background studies were performed with time resolution frames with resulting 32, 16, 8, 4, and 2 Hertz frequency resolution, respectively. • A p-value was obtained for each study by finding the percent of background SNR’s greater than that of the event. • With a p-value of .001 for both the s and SNR BD maps, we can say that we are able to detect the BD. • Whether this provides new information that is not recovered by other pipelines is not certain, but what we can conclude is that STAMP is a viable way to look at short chirp-like events, with some small adjustments in parameters. , 4 Hz Resolution Frames , 4 Hz Resolution, 2000 time-shifted points. B) , 2 Hz Resolution, 2000 time-shifted points. B) , 2 Hz Resolution Frames FIG. 2: Histograms showing the max radon SNR of each event in the background studies. FIG. 1: One second SNR ft-maps centered on the BD using H1L1 cross-correlated data. • Additional attempts are being made to try and make STAMP more applicable to shorter signals in an effort to help provide an additional diagnostic tool in analyzing such events. • Once such effort is to create ft-maps that have a logarithmically spaced y-axis for frequency. This would provide greater frequency resolution in the lower frequency region where the signal is more horizontal and more time resolution when the chirp is more vertical. This is similar to what is done in the Omega Pipeline [ ]. Contact: kremin@physics.umn.edu, ethrane@physics.umn.edu prestegard@physics.umn.edu, mandic@physics.umn.edu Acknowledgments: This research is supported by NSF grant ?????????????.