Observing Gravitational Waves with Advanced LIGO Laura Nuttall on - - PowerPoint PPT Presentation
Observing Gravitational Waves with Advanced LIGO Laura Nuttall on behalf of the LIGO Scientific Collaboration and Virgo Collaboration Syracuse University LIGO-G1602189 LIGO Laser Interferometer Gravitational-wave Observatory LIGO-Livingston
Laura Nuttall on behalf of the LIGO Scientific Collaboration and Virgo Collaboration Syracuse University LIGO-G1602189
Laser Interferometer Gravitational-wave Observatory
LIGO-Hanford LIGO-Livingston
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Weiss’s 1972 design study (Weiss, Electromagnetically Coupled Broadband Gravitational Antenna, 1972 Tech. Rep. MIT)
Photodetector Beam Splitter Power Recycling Laser Source 100 kW Circulating Power
b) a)
Signal Recycling T est Mass T est Mass T est Mass T est Mass Lx = 4 km 20 W H1 L1
10 ms light travel time
Ly = 4 km
Differential changes in arm length measure strain 𝜀L = Lx - Ly = hL
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PRL 116, 131103 (2016)
Higher-power laser Larger mirrors Higher finesse arm cavities Signal recycling cavity Signal recycling mirror Output mode cleaner and more …
Improvements
Comprehensive upgrade of Initial LIGO instrumentation in the same vacuum system
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2007
Better Seismic Isolation
I n c r e a s e d L a s e r P
e r a n d S i g n a l R e c y c l i n g Reduced Thermal Noise
https://dcc.ligo.org/LIGO-P1000103/public
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PRL 116, 131103 (2016)
Typical range: BNS ~ 70 Mpc BBH ~ 580 Mpc
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from 35Hz to peak amplitude at 150 Hz
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PRL 116, 061102 (2016)
~1/200th proton radius
from 35Hz to peak amplitude at 150 Hz
PRL 116, 061102 (2016)
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~1/200th proton radius
PRL 116, 241103 (2016)
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a)
H1 L1
10 ms light travel time
10 ms + 5 ms for uncertainly in arrival time of weak signals
binaries, we construct a bank of template waveforms and matched-filter the data
waveform template in both detectors within the light travel time between sites
statistic value that ranks their likelihood
ρ = s|h⇥ p h|h⇥
a|b⇥ = 4Re Z fhigh
flow
˜ a(f)˜ b(f) Sn(f) d f
100 101 102
m1 [M]
100 101
m2 [M]
|χ1| < 0.9895, |χ2| < 0.05 |χ1,2| < 0.05 |χ1,2| < 0.9895 GW150914 GW151226 LVT151012 (gstlal) LVT151012 (PyCBC)
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x x x x x xx x x x x x events H1 L1 zero lag or foreground
a detection statistic value equal to or higher than the candidate event
multiple detectors
0.1s and computing a new set of coincident events
Usman et al., arXiv: 1508.02357 (2015)
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x H1 L1 x x x x x x H1 L1 x x x xx x 0.1 s 0.1 s Time shifted data 0.1 s
Usman et al., arXiv: 1508.02357 (2015)
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a detection statistic value equal to or higher than the candidate event
multiple detectors
0.1s and computing a new set of coincident events
x x x x x H1 L1 x x x xx Time shifted data background events
x x
Usman et al., arXiv: 1508.02357 (2015)
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a detection statistic value equal to or higher than the candidate event
multiple detectors
0.1s and computing a new set of coincident events
Results from the first observing run (12th Sept 2015 - 19th Jan 2016)
GW151226 LVT151012
2σ 3σ 4σ 5σ > 5σ 2σ 3σ 4σ 5σ > 5σ
8 10 12 14 16 18 20 22 24
Detection statistic ˆ ρc
10−8 10−7 10−6 10−5 10−4 10−3 10−2 10−1 100 101 102 103 104
Number of events
GW150914 Search Result Search Background Background excluding GW150914
GW151226 LVT151012
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Abbott et al., Phys. Rev. X 6, 041015 (2016)
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Abbott et al., Phys. Rev. X 6, 041015 (2016)
Posterior probability densities of the masses, spins and distance to the three events
Abbott et al., Phys. Rev. X 6, 041015 (2016)
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secondary mass
support for unequal mass ratios
Posterior probability densities of the masses, spins and distance to the three events
Abbott et al., Phys. Rev. X 6, 041015 (2016)
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All 3 remnant black holes have spins ~0.7 as expected for the merger of similar mass black holes in a binary
Posterior probability densities of the masses, spins and distance to the three events
Abbott et al., Phys. Rev. X 6, 041015 (2016)
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χeff = χ1m1 + χ2m2 M
1,2 = c Gm2
1,2
~ S1,2 · ˆ L
spin magnitude > 0.2
are disfavoured
Abbott et al., Phys. Rev. X 6, 041015 (2016)
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merger rates depend
distribution - which we don’t know very well yet!
mass distributions
rate is in the range 9-240 Gpc-3yr-1
100 101 102 103
R (Gpc−3 yr−1)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
R p(R) Flat Event Based Power Law
Abbott et al. arXiv: 1606.04856 (2016)
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BNS rate compared to
rate of BNS systems with component masses of 1.35±0.13 M☉ to be less than 12,600 Gpc−3 yr−1
100 101 102 103 104
BNS Rate (Gpc−3yr−1)
aLIGO 2010 rate compendium Kim et al. pulsar Fong et al. GRB Siellez et al. GRB Coward et al. GRB Petrillo et al. GRB Jin et al. kilonova Vangioni et al. r-process de Mink & Belczynski pop syn Dominik et al. pop syn
O1 O2 O3
During O1 we looking for gravitational waves from binary neutron star (BNS) and neutron star - black hole (NS-BH) systems
Abbott et al., arXiv: 1607.07456 (2016)
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compared to other published rates
light blue 1.4-10 M☉
BH systems with BH at least 5 M☉ to be less than 3,600 Gpc
−3 yr −1
(assuming isotropic distribution of component spins)
assumed to be 1-1.9 and 1.9-2.7 times larger than O1
During O1 we looking for gravitational waves from binary neutron star (BNS) and neutron star - black hole (NS-BH) systems
Abbott et al., arXiv: 1607.07456 (2016)
10−2 10−1 100 101 102 103 104
NSBH Rate (Gpc−3yr−1)
aLIGO 2010 rate compendium Fong et al. GRB Coward et al. GRB Petrillo et al. GRB Jin et al. kilonova Vangioni et al. r-process de Mink & Belczynski pop syn Dominik et al. pop syn
O1 O2 O3 25
Image Credit: Caltech/MIT/LIGO Lab
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Abbott et al. Living Reviews in Relativity 19, 1 (2016)
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Abbott et al. arXiv: 1606.04856 (2016)
starting in ~month
christmas followed by a break for the holidays
until early spring when Virgo will join
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1 10
hV Ti/hV TiO1
0% 20% 40% 60% 80% 100%
P(N > {2, 10, 40}|hV Ti) O2 O3
www.ligo.org
1000+ members, 90 institutions, 16 countries
Slide: Gabriela González
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LIGO-G1601165
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Sky localization depends on:
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Abbott et al., Phys. Rev. X 6, 041015 (2016)
Timeline of observations of GW150914, separated by band and relative to the time of the gravitational wave event
100 101 102 t −tmerger (days) Initial GW Burst Recovery Initial GCN Circular Updated GCN Circular (identified as BBH candidate) Final sky map Fermi GBM, LAT, MAXI, IPN, INTEGRAL (archival) Swift XRT Swift XRT Fermi LAT, MAXI BOOTES-3 MASTER Swift UVOT, SkyMapper, MASTER, TOROS, TAROT, VST, iPTF, Keck, Pan-STARRS1, KWFC, QUEST, DECam, LT, P200, Pi of the Sky, PESSTO, UH Pan-STARRS1 VST TOROS VISTA MWA ASKAP, LOFAR ASKAP, MWA VLA, LOFAR VLA, LOFARVLA
Abbott et al. ApJ 826, Number 1 (2016)
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Image Credit: LIGO
SNR = 23.7 SNR = 9.7 SNR = 13.0
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Abbott et al. Phys. Rev. Lett. 116, 131103 (2016)
Time in the sensitive frequency band for binary coalescences
Alex Nitz
Lowest viable searchable frequency for Advanced LIGO (at design sensitivity)
https://www.zooniverse.org/projects/zooniverse/gravity-spy/ Help us classify glitches!
independent realizations of a counting experiment for noise background events.
(which can be < 0.1s) that matters, but rather the autocorrelation function (the width of the peak in the SNR - 1ms)
having ρc > 9 between consecutive time shifts, where Ci denotes the number of events in the ith time shift
Gaussian transients in the data
We performed every check we could think of…
strikes…) and uncorrelated (seismic activity, traffic…) sources of noise
monitors the instrument behavior and environmental conditions
(physically and remotely connected)
Cannot find any instrumental cause - this signal can only be produced from two black holes colliding
A blip transient in LIGO-Livingston strain data that produced a significant background trigger in the CBC analysis in orange, and the best-match template waveform (amplitude-scaled for comparison) in black, which exhibits a few more low-SNR cycles but otherwise quite similar morphology
10 20 30 Time [milliseconds] −1.5 −1.0 −0.5 0.0 0.5 1.0 1.5 Strain amplitude ×10−21
Band-limited h(t) during blip transient Best-match NSBH waveform Best-match GW150914 waveform