1. Brennan Hughey for the LSC May 12th, 2008
Status of LIGO
Brennan Hughey for the LSC
May 12th, 2008
DCC Number: G Z

2. LIGO and Friends LIGO Livingston (LA) L1 – 4km LIGO Hanford (WA)
H1 – 4km H2 – 2km
Virgo 3 km (Italy)
Has data-sharing
agreement with LSC
GEO 600m (Germany)
Part of the LSC
DCC Number: G Z

3. Approximate Timeline S5 S6 S7 VSR1 VSR2 2006 2007 2008 2009 2010 2011
2012
2013
2014 S5
“Astrowatch”
H2 and GEO
Enhanced LIGO
Install/commision S6 S7
and beyond
Advanced LIGO
Funding officially
Began April 2008
Advanced LIGO
Development
Advanced LIGO
Install/commission
Virgo+
VSR2
VSR1
Advanced Virgo
Install/commission
Advanced
Virgo
2006
2007
2008
2009
2010
2011
2012
2013
2014
DCC Number: G Z

4. Enhanced LIGO Improvements include: Better Readout
Prototyping for Advanced LIGO and X2 sensitivity of Initial LIGO
Improvements include:
Better Readout
DC Readout of GW signal instead of RF heterodyning
New output mode cleaner filter cavity cleans up the light
Active steering for beam stabilization
More laser power (thus lower shot noise)
from 10 W to ~35 W
Replacement of several components including thermal
compensation system in test masses to handle higher power
Magnets, Electronics, light power, controls……
DCC Number: G Z

5. Advanced LIGO Builds on improvements in Enhanced LIGO
Order of magnitude improvement in sensitivity relative to Advanced LIGO
Builds on improvements in Enhanced LIGO
All systems (except buildings and basic infrastructure)
are upgraded
Signal recycling
cavity makes
detector tunable
NSF funding
officially started
in April
DCC Number: G Z

6. Reach of ~170 Mpc For standard NS-NS Inspiral in Advanced LIGO
Enhanced LIGO
~2009
LIGO today
Reach of
~170 Mpc
For standard
NS-NS
Inspiral in
Advanced
LIGO
100 million
light years
Advanced LIGO
~2014 6

7. Data Analysis Methods Template-less methods Matched filter Short
Bursts
Stochastic Background
Template-less methods
Compact Binary Inspirals
Pulsars
Matched filter
Short
duration
Long

8. Data Analysis Methods See Peter Shawhan’s talk Overview in this talk
Bursts
Stochastic Background
Template-less methods
Compact Binary Inspirals
Pulsars
Matched filter
Short
duration
Long
See Peter
Shawhan’s
talk
Overview in
this talk
Plus specific topics in other talks throughout this meeting

9. Burst Analyses Sources of GW bursts include: Core-collapse supernovae
Merger of binary compact objects
Neutron star instabilities
Cosmic string cusps and kinks
Unexpected sources?
Approaches:
“All-sky” searches performed over whole sky and over all
Collected data
“Externally triggered” searches performed around the time
Of Gamma-Ray Bursts or Soft Gamma Repeaters
DCC Number: G Z

10. All-sky searches S5 all sky search 4 science runs of LIGO-GEO
instruments in
35 days triple coincidence
No event candidates
Upper limit (90%
confidence level on rate of
detectable events) set S1 S2 S4
LIGO S4 search: CQG 24 (2007) 5343
S5 all sky search
Analysis underway, split
into 2 calendar years
Order of magnitude more
data and X2 sensitivity of S4
Exploiting coherent analysis
methods and full network
Preliminary
Detection Probability

11. High Frequency All Sky Searches
All-sky searches previously limited to 2kHz or lower
New analyses extend range of analysis up to ~6.5 kHz
All source types previously listed can have >2 kHz emission
Use same methods as low frequency, adjusting as needed
Takes full advantage of Virgo
Clean, shot-noise
dominated background

12. Triggered Searches GRB070201 Other GRB analyses
[LIGO Scientific Collaboration: arXiv:
accepted by ApJ]
Combination of inspiral and burst methods
Excludes a compact merger within M31 at >99%
confidence level, although it could be an SGR
Other GRB analyses
39 GRBs in S2, S3, S4 runs [LIGO Scientific Collaboration: Phys. Rev. D 77, (2008), Phys. Rev. D 72, (2005) ]
Additional S5 GRB searches are ongoing – taking advantage of full coherent analysis
Search for GW emission from Soft Gamma Repeaters underway
DCC Number: G Z

13. Backup

14. Initial LIGO Fifth Science Run completed in October 2007
Took place over ~2 calendar years
Gathered over 1 year of triple-coincident H1H2L1 data
Last several months overlap with Virgo (May 18th-Oct 1)
joint analysis improves coverage and pointing accuracy
Data analysis is well underway
(2nd part of this talk and several other talks)
Astrowatch is ongoing during H1 and L1 upgrades
Employs H2 and GEO
Primary goal is to have instruments online in case
of an extremely interesting astrophysical event
Student-led operation
DCC Number: G Z

15. Coherent analysis methods
Naturally handles arbitrary networks of detectors
Analysis repeated as a function of frequency and sky position
Produces significance and consistency sky maps
Coherent sum:
Find linear combinations of detector data that maximize signal to noise ratio
coherent sum
N-2 dimensional null space
detector data
coherent null
2 dimensional signal space
data = response x signal noise
Null sum:
Linear combinations of detector data that cancel the signal provide useful consistency tests.
Gursel and Tinto, PRD 40 (1989) 3884
Klimenko, et al., PRD 72 (2005)
Rakhmanov, CQG 23 (2006) S673
Wen and Schutz, CQG 22 (2005) S1321
Chatterji, et al. PRD 74 (2006)
DCC Number: G Z

16. Summary of Burst Search Approach
Data stream is projected onto a Fourier or Wavelet basis
Threshold on power and form clusters of triggers
Require coincidence in time and frequency between sites
Cross-correlation of strain data from pairs of detectors
Use data quality and vetoes to remove shaky data
- high seismic noise, wind, planes, calibration line dropouts, last
30 seconds of each science segment……..
Characterize background via unphysical “timeshifts” between detectors
frequency
time
Instument 1
Instument 2
LIGO S4 search: CQG 24 (2007) 5343