Method

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 Doc. LIGO-G1100948 • Stochastic Transient Analysis Multi-Detector Pipeline (STAMP) uses data cross-correlated from spatially separated detectors to search for long gravitational wave (GW) transients that last several seconds or more [1]. • However, can we use STAMP to look for short transients as well? E.g black hole inspirals? • Our case study is a hardware injection known as the “Big Dog” (BD) event. • The BD has been thoroughly investigated by other pipelines. • Thus, this case study is a way to determine whether data cross-correlation can provide a simple cross-check for such analyses. • Rough estimates of the p-values were found based on a sample of time-shift maps. • The most significant results were found with and resolution maps, which each had significance of roughly 0.05%. • P-value approximations exclude the OMC Spike Glitch, which was identified and removed from the time-shift studies. • No time-shift study was performed for the 1/32s resolution because the event was not visible in the SNR plot. • Four time-shift studies were performed: Motivation Next Steps References Results Method Conclusions • Data from the Hanford (H1) and Livingston (L1) observatories were cross-correlated to make frequency-time (ft) maps of the signal to noise ratio (SNR). • A Radon search algorithm was employed to determine the maximum SNR for each map. • The results of the BD were compared with time-shifted SNR maps to estimate the significance. • Five pixel resolutions were tested: OMC Spike Glitch OMC Spike Glitch (A) (B) FIG. 3: Histograms showing the max radon SNR of each time-shift event (Blue) in relation to the BD max Radon SNR (Red). (A), 8 Hz resolution results. (B) , 4 Hz resolution results. • P-values of ~0.05% for both the s and BD time-shift studies show that we were able to detect the BD with STAMP. • We can conclude that STAMP provides a simple way of looking at short GW transients as well as longer duration signals. • STAMP may be a useful diagnostic tool in future analyses. (A) (B) FIG. 1: SNR ftmaps centered on the BD using H1L1 cross-correlated data. The BD is visible as yellow and white pixels ascending to higher frequencies at roughly .4s. (A) STAMP plot of BD with 1/8, 8 Hz resolution frames. (B) STAMP plot of BD with 1/4s, 4 Hz resolution frames.(C) Preliminary result of a logarithmically binned ft SNR map of the BD produced using modified STAMP code. • Try logarithmic binning of the ftSNR maps. See Fig. 1(C), [2] and [3]. • Test the usefulness of logarithmic binning as a diagnostic tool for both short and long GW transients. (C) • [1] E. Thrane et al. Long gravitational-wave transients and associated detection strategies for a network of ground-based interferometers. (Submitted to Phys. Rev. D, 2010). • [2] R. Khan and S. Chatterji, Class. Quantum Grav. 26, 155009 (2009). • [3] S. Chatterji. The search for gravitational wave bursts in data from the second LIGO science run. (Doctoral Dissertation). LIGO Doc. P050033-00 (2005). • [4] The LIGO and Virgo Collaborations.Evidence for the Direct Detection of Gravitational Waves from a Black Hole Binary Coalescence. LIGO Doc. LIGO-P1000146-v16 (2010). FIG. 2: Omega Pipeline plot of the detected BD observed in the LHO. The event is visible as a chirp-like line moving toward 0 seconds[4]. 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 PHY0758036.