CBC inspiral papers S1 Analysis of LIGO data for gravitational waves from binary neutron stars Phys Rev D 69 2004 122001 grqc0308069 S2 Search for gravitational waves from galactic and extragalactic binary neutron stars ID: 572851
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Slide1
A walk through some statistic details of LSC resultsSlide2
CBC (“inspiral
”) papers
S1:
Analysis of LIGO data for gravitational waves from binary neutron stars.
Phys. Rev. D
69
(2004) 122001
gr-qc/0308069
S2:
Search for gravitational waves from galactic and extra-galactic binary neutron stars.
Phys. Rev. D
72
(2005) 082001
gr-qc/0505041
S3/S4:
Search for gravitational waves from binary
inspirals
in S3 and S4 LIGO
data
Phys
. Rev. D
77
(2008) 062002
arXiv:0704.3368
S5/VSR1:
Search for Gravitational Waves from Compact Binary Coalescence in LIGO and Virgo Data from S5 and VSR1
Phys. Rev. D
82
(2010) 102001
arXiv:1005.4655
Also
Sensitivity to Gravitational Waves from Compact Binary Coalescences Achieved during
LIGO's
Fifth and Virgo's First Science Run,
arXiv:1003.2481
S6/VSR2, 3:
Search for Gravitational Waves from Low Mass Compact Binary Coalescence in
LIGO's
Sixth Science Run and Virgo's Science Runs 2 and 3
arXiv:1111.7314
P1100034
. Also
Sensitivity Achieved by the LIGO and Virgo Gravitational Wave Detectors during
LIGO’s
Sixth and Virgo’s Second and Third Science Runs,
arXiv:1203.2674Slide3
7/9/2003
LIGO Scientific Collaboration - Amaldi 2003
3
How to detect inspiral waves
Use template based matched filtering algorithm
Template waveforms for non-spinning binaries
2.0 post-Newtonian approx.
D: effective distance; a: phase
Discrete set of templates labeled by I=(m1, m2)1.0 Msun < m1, m2 < 3.0 Msun2110 templatesAt most 3% loss in SNR
s(t) = (1Mpc/D) x [ sin(a) h
I
s
(t-t0) + cos(a) h
I
c
(t-t0)]Slide4
7/9/2003
4
Optimal Filtering Using
FFTs
Transform data to frequency domain :
Calculate template in frequency domain :
Combine, weighting by power spectral density of noise
, and
then inverse Fourier transform gives the filter output at all times:
Find maxima of over arrival time and phaseSlide5
7/9/2003
LIGO Scientific Collaboration - Amaldi 2003
5
“Chi-Squared Veto”
Many large glitches in the data can lead to a filter output with large SNR
The essence of a “chirp” is that the signal power is distributed over frequencies in a particular way
Divide template into sub-bands (
p
=8) and calculate
2:
Correct for large signals which fall between points in template bank and apply a threshold cut: Slide6
Multiple detectors: S2 exampleSlide7
Results of a search
Candidates and their significance (detections?).
Upper limits on rate of coalescences (
frequentist
or Bayesian). Slide8Slide9
7/9/2003
LIGO Scientific Collaboration - Amaldi 2003
9
S1
Inspiral
Search: results
Use triggers from H 4km and L 4km interferometers:
T = 236 hours
Max SNR observed: 15.9 An event seen in L1 only, with effective distance = 95
kpc
There are
no event candidates in the coincidence category
Monte Carlo simulation
efficiency for SNR=15.9:
e
= 53%
Effective number of
Milky Way-equivalent galaxies
surveyed: NG=
e(Lpop/LG
)=0.53x1.13=0.60Uncertainties (calibration, etc): Slide10
7/9/2003
LIGO Scientific Collaboration - Amaldi 2003
10
Inspiral Search: results
Limit on binary neutron star coalescence rate:
R90% (Milky Way) < = 2.3
x
(1/N
G
) (1/T) = 140 (0.60/NG) /yrWith NG
=0.60-0.10 we derive R< 170 /yr /MWEGCompare with:Previous experimental results:
LIGO 40m ‘94: 0.5/hr (25hrs, D<25kpc, Allen et al., PRD 1998)
TAMA300 ’99: 0.6/hr (6 hr, D<6kpc,
Tagoshi
et al., PRD 2001)
TAMA300 DT6: 82/yr (1,038 hr, D<33
kpc
, GWDAW 2002)
Expected Galactic rate: ~10-6 - 5 x 10-4 /yr (
Kalogera et al)Slide11
7/9/2003
LIGO Scientific Collaboration - Amaldi 2003
11
S1 search: Loudest
Surviving Event Candidate
Not NS/NS
inspiral
event!
2 Sep 2002, 00:38:33 UTC
S/N = 15.9, c2/dof = 2.2
(m1,m2) = (1.3, 1.1) Msun
What caused this?
Appears to be saturation of a photodiode
SNR
c
2
test
GW channel
Actual trigger
Injected signalSlide12
S2 run Slide13
S2 run: a new statistic, and an estimate of the backgroundSlide14
S2 run: candidatesSlide15
S2 run: background revisitedSlide16
S2: upper limitSlide17
S3/S4: sensitivity, statisticsSlide18
S3/S4:
B
ayesian upper limitSlide19
S3/S4: upper limitSlide20
S5: new statisticSlide21
S5 Results, upper limitSlide22
S5 Results – and blind injectionSlide23Slide24
7/9/2003
LIGO Scientific Collaboration - Amaldi 2003
24
Days in S1
LIGO sensitivity
S1: 23 Aug – 9 Sep, 2002
Inspiral sensitivity measured in distance to 2 x 1.4 Msun optimally oriented inspiral at signal to noise = 8
Livingston: <D> = 176 kpc
Hanford: <D> = 46 kpc
Sensitive to inspirals in
Milky Way, LMC & SMCSlide25
Keeping interferometer locked
S1 run: 17days (408 hrs)
Seismic Noise in the
band