SLIDE 1
. Plan of talk
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LIGO-Virgo data analysis Archisman Ghosh Nikhef, Amsterdam 7 th - - PowerPoint PPT Presentation
LIGO-Virgo data analysis Archisman Ghosh Nikhef, Amsterdam 7 th - - PowerPoint PPT Presentation
. LIGO-Virgo data analysis Archisman Ghosh Nikhef, Amsterdam 7 th Belgian-Dutch Gravitational Waves Meeting Van Swinderen Institute for Particle Physics and Gravity, University of Groningen 2018 May 29 . Plan of talk Orientation and basics
SLIDE 2
SLIDE 3
. Gravitational-wave sources
3 of 16 Cosmological + BBH Supernova explosions Spinning deformed NS NS-NS, NS-BH, BBH
Weak Strong Unmodelled Stochastic background Bursts Modelled Continuous waves Compact binary coalescences
SLIDE 4
. Data analysis of CBCs
4 of 16 Generate (real-time) triggers Rigorous analysis of data around trigger Fundamental physics, astrophysics, cosmology Abbott et al., PRX 6, 041015 (2016)
Searches Parameter estimation Implications Low latency
quick BayesSTAR RapidPE
High latency
accurate LALInference
SLIDE 5
. Searches
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BACKGROUND COINCIDENT TRIGGER TEMPLATE BANK MATCHED FILTERING RANKING & SIGNIFICANCE
For further details: Sarah Caudill
Abbott et al., PRX 6, 041015 (2016)
SLIDE 6
. Parameter estimation
6 of 16 Veitch & Vecchio (2009); Veitch et al. (2014)
Intrinsic parameters: {m1, m2, s1, s2, λ1, λ2, . . .} Extrinsic parameters: {α, δ, dL, ι, ψ, φc, tc}
At least 15 parameters for BBHs At least 17 parameters for BNS
Bayesian parameter estimation: obtain the posterior probability distribution on the parameter space given the data and a prior probability distribution.
Posterior( Ω|data, I) = Prior( Ω|I) L(data| Ω, I) Evidence(data, I)
LALInference: to perform a stochastic sampling of the posterior probability distribution over parameter space.
SLIDE 7
. Parameter estimation results
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10 20 30 40 50 60 primary mass (M ⊙ ) 5 10 15 20 25 30 35 40 secondary mass (M ⊙ ) LVT151012 GW170608 GW170814 GW150914 GW170104 GW151226
LIGO/Virgo/Patricia Schmidt LIGO/Virgo/NASA/Leo Singer (Milky Way image: Axel Mellinger)
GW150914 GW151226 LVT151012 GW170104 GW170814 GW170817 GW170608 GW150914 Abbott et al., PRL 116, 061102 (2016) GW170817 Abbott et al., PRL 119, 161101 (2017)
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.
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|T|=|Eb/ . Eb| [s]
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R
1/2=(M/L 3) 1/2 [km
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Double Binary Pulsar Lunar Laser Ranging GW150914
- f Mercury
Perihelion Precession LAGEOS Pulsar Timing Arrays GW151226
Yunes et al. (2016) Abbott et al., PRL 116, 061102 (2016) Abbott et al., PRL 116, 221101 (2016)
Testing general relativity
First probes into the dynamical regime of strong field general relativity (GR).
SLIDE 9
. Inspiral-merger-ringdown consistency test
9 of 16 GW150914 Abbott et al., PRL 116, 221101 (2016) Abbott et al., PRL 118, 221101 (2017) GW150914 + GW170104
Mass and spin of the remnant object estimated from the inspiral and merger-ringdown parts agree with each other given GR predictions.
Ghosh et al. (2016); Ghosh et al. (2017)
Might not have been true in modified GR.
Stronger constraints on systematic departures from GR combining information from multiple detections.
SLIDE 10
. Constraints on parameterized deformations from GR
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v c 0 v c 1 v c 2 v c 3 v c 4 v c 5 v c 6 v c 7
GW150914 + GW151226 + GW170104 GW150914
− − − − →
Li et al. (2011); Agathos et al. (2013); Meidam (PhD thesis, 2017); Meidam et al. (2017) Abbott et al., PRL 116, 221101 (2016) Abbott et al., PRL 118, 221101 (2017)
Allowing coefficients in waveform models to deviate from their GR values, the deviation parameters do not show any departure from their GR values. First-ever measurement of orbital dynamics beyond leading order in v/c.
Deviation in
- v
c
3 coefficient constrained to O(10%) Dynamical self-interaction of spacetime Spin-orbit interaction
SLIDE 11
. Constraints from modified dispersion
11 of 16 GW150914 + GW151226 + GW170104 GW150914 + GW151226 + GW170104 GW170104 Abbott et al., PRL 118, 221101 (2017) Will (1998); Mirshekari et al. (2012) Agathos (PhD thesis, 2016); Samajdar (PhD thesis, 2017); Samajdar & Arun (2017)
Hubble scale ≈ 1.3 × 1023km
Modified dispersion relation:
(different frequencies travel with different speeds)
E 2 = p2c2 + A pαcα λA ≡ hcA1/(α−2)
α = 0 → local Lorentz invariance violation α = 0 → massive graviton
λg ≡ h mgc > 1.6 × 1013km mg < 7.7 × 10−23eV/c2
Effect gets enhanced with propagation over a distance!
SLIDE 12
. Polarization from 3-detector observation of GW170814
12 of 16 Abbott et al., PRL 119, 141101 (2017) Isi & Weinstein (2017) Need multiple detectors: thanks to Virgo!
six polarizations − → distinct antenna patterns In GR: GW are transverse, traceless
- nly tensor polarizations
pure tensor / pure scalar = 1000 / 1 pure tensor / pure vector = 200 / 1
SLIDE 13
. Constraints from GW170817+GRB
13 of 16 Abbott et al. Astrophys. J. 848 #2, L13 (2017)
Delay of only a few seconds after a propa- gation over one hundred million light years. tEM − tGW = 1.74 ± 0.05 s Constraints on speed of gravity assuming GRB emitted within 10s of GW −3 × 10−15 vGW − vEM vEM +7 × 10−16 “Shapiro time delay” of GW and EM in the gravitational potential of our galaxy: −2.6 × 10−7 γGW − γEM 1.2 × 10−6 Test of the equivalence principle.
SLIDE 14
. Probing the nature of the progenitor and remnant compact objects
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Are they really black holes, or exotic compact objects mimicking black holes? Boson stars, dark matter stars, gravastars, shells, wormholes Three “complementary” ways in three different regimes:
♣ Anomalous tidal effects during inspiral. ♣ No-hair theorem with quasinormal modes.
Talk by Anuradha Samajdar
♣ Search for post-merger oscillations or “echoes”.
Talk by Ka Wa Tsang
SLIDE 15
. Cosmology: Hubble parameter with GW170817
15 of 16 Optical counterpart: SSS17a Host galaxy: NGC 4993
- bserved
vrecession = vH + vpeculiar universe is not homogeneous at small scales: galaxies attracted towards local matter overdensities NGC 4993: vrecession = 3327 ± 72 km s−1 Correct for peculiar velocity of group of galaxies vH = 3017 ± 166 km s−1 Distance, dL = 43.8+2.9 −6.9Mpc (assuming sky location of counterpart)
Independent of any distance ladder!
Abbott et al. Astrophys. J. 848 #2, L12 (2017); LSC-EPO Abbott et al. Nature 551 #7678, 85-88 (2017)
H0 = 70.0+12.0
−8.0 km s−1Mpc−1
More details and future prospects in talk by Ankan Sur
SLIDE 16
. Summary and outlook
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