LIGO / Virgo / KAGRA strain detection; matched-filter waveform templates; binary inspiral / merger / ringdown; multi-messenger GW170817 / kilonova; pulsar-timing-array nano-hertz; LISA; numerical relativity; stochastic background.
Gravitational Wave Physics
Gravitational-wave strain detection
LIGO Michelson Fabry-Perot interferometer detects strain h ~ 10^-21 over 4 km baseline; quantum-noise-limited above 100 Hz,…
Matched-filter template matching
Optimal SNR detection via matched-filtering of strain data with theoretical waveform bank; PyCBC / GstLAL pipelines run on millions of…
Binary inspiral waveform (post-Newtonian)
Post-Newtonian expansion in v/c gives chirp-mass M_c = (m1 m2)^(3/5) / M^(1/5); inspiral amplitude grows as f^(2/3); 3.5PN waveforms…
LIGO-Virgo-KAGRA network
3-detector network (Hanford, Livingston, Virgo) plus KAGRA (2020) localizes sources to about 10-100 deg^2; LIGO-India planned for 2030 will…
Binary neutron-star merger
GW170817 (Aug 17 2017): first BNS detection plus EM counterpart (GRB170817A); kilonova AT2017gfo confirmed r-process nucleosynthesis;…
Multi-messenger astronomy GW170817
Joint GW + gamma-ray + optical + radio + X-ray observation of BNS merger across 70 telescopes; verified neutron-star-merger origin of…
Stochastic gravitational-wave background
Cosmological (inflation, cosmic-strings, phase-transitions) plus astrophysical (BBH-merger superposition) backgrounds; Omega_GW(f)…
Cosmological GW sources
Primordial inflation tensors (B-mode CMB), preheating, first-order phase-transitions, cosmic-strings; spectrum extends from sub-Hz to GHz;…
Pulsar-timing-array (nanohertz)
NANOGrav, EPTA, PPTA, IPTA monitor millisecond-pulsars; 2023 evidence (~3 sigma) for nanohertz stochastic background, likely from…
LISA space-based detector
ESA-NASA Laser Interferometer Space Antenna: 2.5-million-km arms, launch 2035; targets mHz band — supermassive-BBH merger, EMRI,…
Numerical relativity
Pretorius 2005 first stable BBH merger; BSSN and Z4c formulations; SpEC (Caltech) and Einstein-Toolkit production; provides waveform…
Kilonova and r-process
Neutron-rich ejecta from BNS merger drives rapid-neutron-capture (r-process) nucleosynthesis; resulting kilonova peaks 1-10 days…
Ringdown quasinormal modes
Post-merger black hole oscillates with characteristic complex frequencies omega_lmn = omega_R + i omega_I depending on mass + spin; first…
GW150914 first direct detection (2015-09-14)
First direct detection: 36+29 solar-mass black-hole merger at 1.3 Gly; SNR 24; 21 cycles in band; chirp-mass 30 solar masses; matched…
Primordial black hole + GW bounds
MACHO-BHs as dark-matter candidate; LIGO-O1+O2+O3 merger-rate places upper-bound on PBH fraction f_DM at masses 1-100 solar-mass; current…
GW memory effect (Zeldovich-Polnarev / Christodoulou)
Permanent strain after GW passage from non-linear gravitational radiation; predicted Zeldovich-Polnarev 1974 + Christodoulou 1991; not yet…
Hellings-Downs correlation (PTA)
Hellings-Downs 1983: angular-correlation in pulsar-timing residuals for stochastic-GW background; quadrupolar pattern with ~1/3 amplitude…
Standard-siren H0 measurement
Schutz 1986 method: GW amplitude gives luminosity distance directly (no calibrator); GW170817 EM-counterpart gave H0 = 70 +/- 12 km/s/Mpc;…
First detection (LIGO 2015)
LIGO 2015 GW150914 + Weiss-Barish-Thorne (Nobel 2017); modern modern foundational + 100+ events O1-O4 + 2024 KAGRA + LIGO-India coming.
GW170817 + EM (2017)
LIGO-Virgo + 70+ partners 2017 BNS + kilonova; modern modern foundational + r-process + standard-siren H_0 + 2024 multi-messenger network.
Primordial GW (BICEP/Keck 2014)
BICEP2 2014 + 2021 r<0.036; modern modern foundational + LiteBIRD + Simons-Observatory CMB-S4 + 2024 polarimetry r-target.
PTA (NANOGrav 2023)
NANOGrav-EPTA-PPTA-CPTA 2023 nHz stochastic-GW; modern modern foundational + 2024 IPTA-DR3 + binary-SMBH most-likely source.
LISA (2034 launch)
ESA-LISA 2024 adoption + 2034 launch space-based mGW; modern modern foundational + 2024 LISA-Pathfinder demonstrated drag-free 10^-15 m/s².
Squeezed vacuum (LIGO 2019)
Aasi-LIGO 2013 + 2019 frequency-dependent-squeezed; modern modern foundational text + 2024 50% sensitivity boost above-quantum noise.