1. Gravitational Wave Data Analysis  GW detectors  Signal processing: preparation  Noise spectral density  Matched filtering  Probability and statistics  Software implementation

2. Gravitational Wave Data Analysis Gravitational Wave Detectors Junwei Cao ( 曹军威 ) and Junwei Li ( 李俊伟 ) Tsinghua University Gravitational Wave Summer School Kunming, China, July 2009

3. Gravitational Waves  Gravitational waves are prediction of Einstein’s General Theory of Relativity.  No direct detection of GWs is successful for nearly 100 years.  A new window to observe the universe

4. Strength of GWs  For the binary system shown in the figure, the strain h=2δl/l becomes h~R 1 R 2 /Dd  For neutron stars of 1.4M ⊙ out at Virgo cluster (15Mpc): h~10 -21  Crazy but within current reach! Binary: a typical GW source

5. Frequency Ranges

6. Laser Interferometers  The Michelson interferometer measures phase differences between two returning beams recombined at the beam splitter. (Albert A. Michelson, 1852- 1931, Nobel Prize 1907)  Modern interferometers use lasers

7. GW Laser Detectors LIGO Simultaneously detect signal (within msec) GEO Virgo TAMA AIGO

8. GW Laser Detectors (Contd.)

9.  LIGO: Laser Interferometer Gravitational wave Observatory ( 激光干涉引力波天文台 )  U.S. NSF flagship project with largest single investment; a joint effort of Caltech and MIT  LSC: the LIGO Scientific Collaboration over 500 scientists from over 60 institutes worldwide LIGO Hanford Observatory (H1, H2)LIGO Livingston Observatory (L1) LIGO & LSC

10. LIGO Experiences

11. LIGO Status  LIGO deliverable – S5 run with over 1 year triple coincidence, no gold-plated detection  Enhanced LIGO – 2 times sensitivity improvement, S6 starts in July 2009  Advanced LIGO – 10 times sensitivity improvement, 103 times signals and frequent GW detections are expected

12. Struggle Against Noises

13. LIGO Data  Data are comprised of:  Gravitational Wave channel (AS_Q)  Physical Environment Monitors  Internal Engineering Monitors  Multiple data products beyond raw data  RDS_R_L1, including both GW and environmental channels  RDS_R_L3, including only AS_Q channel L-RDS_R_L3-751658016-16.gwf Site (H,L) Data Type GPS Start Time Duration

14. GW Data Analysis  Burst, Inspiral, Stochastic, Continuous  Signal processing, probability, statistical analysis  Online, offline, real-time  Matlab, DMT(C++), Scripts (Python)  Clusters, grids, …

15. Gravitational Wave Data Analysis Junwei Cao jcao@tsinghua.edu.cn http://ligo.org.cn