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Round table: What evidence would make a convincing case for the first GW detection claim?

An introduction to border-line cases for gravitational wave (GW) detection, discussing burst searches and binary inspiral searches. The presentation raises questions about the convincing nature of the evidence and invites opinions from the round table panel. Fictional cases are presented without detailed descriptions of event quality, background quality, and analysis robustness.

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Round table: What evidence would make a convincing case for the first GW detection claim?

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  1. Round table: What evidence would make a convincing case for the first GW detection claim? An Introduction B. Mours (LAPP-CNRS) & S. Whitcomb (LIGO-Caltech)

  2. Goal of this introduction • Present a few border line cases for a detection • Oversimplified cases. No description of the event quality, background quality, robustness of the analysis, theoretical predictions… • Ask to the round table panel (and everyone): • Would it be convincing? • If not, what do you expect the be convinced? • Avoid discussing less likely gold-plated cases like • Very loud GW signal in several detectors in coincidence with EM signal and/or neutrinos • Loud periodic signal from a know pulsar observed in several GW detectors • ... Remark: this is just fiction and do not correspond to real cases… … up to now. Round table introduction

  3. H1, H2 V1 Case 1: Burst Search L1 • Single event • No EM or neutrino counterpart • One coincident event in L1, H1 and V1 • H2 down (known to produce higher glitch rate in H1, but accounted for in FAR estimate below) • H1 and L1 have good cross-correlation, so-so with V1 • L1, H1 amplitudes consistent, V1 amplitude 25% larger • A duration of ~15 ms and a central frequency of 750 Hz • Time delays within boundaries : • H1 to V1 delay is ~12 ms; H1 to L1 delay –0.3 ms or –1.6 ms • Inverse False Alarm Rate is between 1000 and 5000 years • Estimated by time slides • IFAR of 5000years for a 6 months run → Probability = 10-4 = “3.9s “ • No other event in a six months run • How convincing would this be? Round table introduction

  4. Case 2: Binary Inspiral Search • Event 1 – second week of science run – ~ 35 Solar mass system • Observed in H1, H2, L1, V1 • IFAR ~ 200 yrs (Probability = 0.25% = “3s “) • It barely passes the c2 test, particularly bad for V1 (broadest bandwidth) • Highest SNR template different among different detectors, • required spin to modulate amplitude and phase • The time delay between detectors is between +130 ms and -60 ms • depending on which template is used for the coincidence • H1 amplitude 1.25 x V1, H2 amplitude 1.2 x V1, L1 amplitude = 0.8 V1 • Event 2 - end of the 6 months run – 1.4+1.6 Solar mass system • Observed in H1, H2 and V1; L1 off-line. • IFAR ~ 50 yrs (Probability = 1% = “2.6s “) • H1 amplitude 1.25 x V1, H2 amplitude 0.9 x V1 • It passes the c2 test cleanly • Time delay within boundaries • Distance estimate is ~50 Mpc • Galaxy density higher by ~4 for the fraction of the sky compatible with time delay • Is either event by itself convincing? What about the two together? Round table introduction

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