Detection of Gravitational Waves  

In General > s.a. gravitational radiation / gravitational-wave analysis; graviton; sources.
* General comment: Electromagnetic astronomy is slanted towards hot places in the universes, and we may be missing places with a lot of matter.
* Physics motivation: Their detection will give, in addition to new tools for astronomy and possible unexpected effects, (i) Direct evidence for time-varying metrics; (ii) Spin and polarization, rest mass and velocity of gravitons; (ii) Tests of strong-field general relativity and black holes – wave forms and df/dt will probe black-hole geometry and test no-hair theorems, general relativity makes precise predictions re overtones in ringing; (iv) Inner dynamics of stars hidden from electromagnetic observations; (v) Insight into Planck-era physics.
* Remarks on detection: Gravitational waves produce very small effects, but detection methods measure their amplitude rather than their intensity, and their amplitude decreases more slowly with distance from the source; They cannot be absorbed or shielded and, although the detector's orientation greatly affects its sensitivity, in principle a detector placed anywhere on Earth could detect gravitational waves from any source.
* 1989: Binary pulsar data and general relativity agree to 1% (at 2+1/2 order in PN expansion); Prediction that it will be possible to detect radiation from collapse in the Virgo Cluster in this century [turned out to be wrong].
* 2004: New Scientist sets the chances of detection by 2010 at 500/1, 5 times less likely than finding Elvis alive.
* 2010: The expectation is that Advanced LIGO will see 1.35-solar-mass neutron star–neutron star mergers at 100Mpc with a signal-to noise ratio ~30 in a 10-year time scale, the Einstein Telescope with a snr of ~500 in a few decades.
* 2012: Measurements of the orbital decay of the white-dwarf binary J0651 (done with an optical telescope more quickly and easily than those for the millisecond pulsar) confirm the predictions of general relativity, within measurement errors and ignoring possibly relevant finite-size effects such as tidal deformations.
* 2014: Measurement of the cmb polarization shows imprints of gravitational waves during inflation; The first generation of interferometric detectors have proved the viability of the approach, and large laser interferometers have surpassed resonant "bar" detectors in sensitivity over the last decade.
* 2016: Direct detection announced on 11 February by LIGO of the GW150914 signal, from binary black-hole (36 + 29 solar masses) coalescence 14 Mpc away; The second detection, of GW151226 from a 14 + 7.5-solar-mass black-hole binary 440 Mpc away, was announced on 15 June.
* 2017: Third detection by LIGO announced, of GW170104 from a binary system with 31 + 19 solar-mass black holes 880 Mpc away.
@ Status: news nat(14)jul; news guard(15)jan, guard(15)jan [rumors of detection]; Berti Phy(16)feb [detection]; news pt(16)mar [re Nat Phys editorial]; news sn(17)jun [third detection].

Resonant Bar Antennas > s.a. QCD effects [as quark-nugget detectors]; non-commutative spacetime.
* Original Weber bar: A large freely suspended bar oscillating longitudinally on resonance (use SQUIDs, with motion detected by a transducer); 1986 sensitivities (δL)/L of about 10–18 (enough only for rare events in our galaxy); Sufficient (40 mK) cooling of the bar and low-noise SQUIDs could give about 3 × 10–21, from zero-point motion.
* Spherical bar detectors: Truncated icosahedra; Motivated by their directional resolution.
* 2000: The IGEC (International Gravitational Event Collaboration), the first ever network of 5-m, 2000-kg cryogenic resonant-cylinder gravity wave detectors, is now operational; It consists of five widely spaced detectors, one in the US (ALLEGRO, in Baton Rouge), two in Italy (Auriga and NAUTILUS, in Legnaro and Frascati), one at CERN (Explorer), and one in Australia (Niobe, in Perth); It is setting bounds on events in our galaxy.
* 2006: Plans for spherical detectors, e.g., MiniGRAIL.
@ General references: Mauceli et al PRD(96) [ALLEGRO]; Astone et al PRL(00), PLB(01) [NAUTILUS, cosmic rays]; Frasca gq/00-proc [status]; Allen et al PRL(00) [bursts]; Finn CQG(03)gq [comments on status]; Sisto & Moleti IJMPD(04) [sensitivity]; Astone et al PRD(07) [IGEC-2 search for bursts]; AURIGA & Virgo CQG(08)-a0801 [cross-correlation method]; Aguiar RAA(11)-a1009 [rev]; Astone et al PRD(13) [EXPLORER and NAUTILUS, 3-year-data analysis].
@ Torsion-bar antennas: Ando et al PRL(10) [for low-frequency waves]; Ishidoshiro et al PRL(11) [upper limit on gravitational-wave backgrounds at 0.2 Hz]; Shoda et al PRD(14)-a1311 [upper limit on gravitational-wave backgrounds]; Eda et al PRD(14)-a1406 [new antenna configuration]; Shoda et al a1611.
@ Spherical: Briant et al PRD(03)gq [nested spheres]; Gasparini PRD(05)gq [performance]; Magalhaes et al PRD(05) [lightning]; Costa & de Aguiar gq/06/PRD [analysis]; Prasia & Kuriakose IJMPD(14).
@ Acoustic detectors: Lobo PRD(95)gq/00; Finn gq/96-proc; Lobo & Montero CQG(02)gq [stochastic background]; Goryachev & Tobar PRD(14)-a1410 + news pw(14)oct [high-frequency phonon trapping cavities].

Other Methods > s.a. interferometers and space-based detectors.
* MIGO: Matter-wave interferometers, using atomic beams emanating from supersonic atomic sources that are further cooled and collimated by means of optical molasses; The sensitivities compare favorably with LIGO and LISA, but the sizes of MIGOs can be orders of magnitude smaller, and their bandwidths wider.
* Indirect methods: One includes pulsar timing, monitoring binary pulsars over long periods of time and finding small residual variations in the signal that can be attributed to fluctuations in the metric near the system; 2012, Another is to monitor close binary white dwarf systems.
* Pulsar timing: The method is insensitive to half of the gravitational-wave sky (the curl modes).
* Precision astrometry: Somewhat similar to pulsar timing; One can look for quadrupole-like periodic changes in Milky Way star patterns that are affected by gravitational waves from extragalactic (very distant or primordial) sources; Gravitational-wave memory effects could possibly be seen; A space mission that can make the measurements is GAIA; Sources would be supermassive or primordial black holes, and the relevant frequencies in the 10–7-10–8 Hz range.
@ Using light: Bergmann PRL(71); Mitskiewich & Nesterov GRG(95) [geometric phase]; Tamburini et al a0804 [photon entangled states]; Kulagin et al a1605 [opto-acoustical detector]; Kolkowitz et al a1606 [optical lattice atomic clocks].
@ Superconductors: Gemme et al gq/01-conf [coupled cavities]; Chiao gq/02-ch [Meißner-like effect], gq/02-ch; Golovashkin gq/03-conf; Chiao et al a0903; Chiao a1011 [figure "8" detector]; Gulian et al JPCS(14), a1409.
@ Using storage rings: Zer-Zion APP(00); Ivanov & Kobushkin gq/02.
@ MIGO: Chiao & Speliotopoulos JMO(04)gq/03; Roura et al PRD(06)gq/04 [no better than LIGO]; Dimopoulos et al PLB(09)-a0712, PRD(08)-a0806; Geiger et al a1505, Canuel et al SPIE-a1604 [MIGA project overview].
@ Atom interferometers: Tino & Vetrano CQG(07)gq [possibility]; Tino & Vetrano CQG(07)gq [possibility]; Chaibi et al PRD(16)-a1601 [low-frequency]; Geiger a1611-ch [rev]; Lefèvre et al a1705-proc; Norcia et al a1707.
@ Other matter-wave interferometers: Foffa et al PRD(06); Delva et al PLA(06)gq [vs light-wave]; Hogan et al GRG(11)-a1009 [AGIS-LEO]; issue GRG(11)#7; Vetrano & Viceré EPJC(13)-a1304 [Newtonian noise]; Graham et al PRL(13) + news nbc(13)may; Tang et al RAA(15)-a1312.
@ Precision astrometry: & Braginsky et al (90); Fakir ap/95; Book & Flanagan PRD(11)-a1009 [gravitational-wave background]; Titov & Lambert a1603-TX [using VLBI].
@ Radio waves, pulsar timing: Manchester a1004-MG12; Adami et al a1011-wd; Rodin a1012-proc, AR(11)-a1101; Wang et al ApJ(14)-a1406; Liu et al a1509 [relic waves, effects of cosmic phase transitions]; Taylor et al ApJL(16)-a1511 [detection prospects]; Burke-Spolaor a1511-PASP [rev]; Mingarelli 16-PhD; Cornish & Sampson PRD(16)-a1512; > s.a. pulsars.
@ Solar System / astrophysics: Armstrong LRR(06) [spacecraft Doppler tracking]; news PhysOrg(12)aug, bbc(12)aug [binary white dwarf system J0651]; Coughlin & Harms PRL(14)-a1401, PRD(14) [seismic data from Earth ringing]; Lopes & Silk ApJ(14)-a1405 [helioseismology and asteroseismology]; Loeb & Maoz a1501/PRD [atomic clocks distributed along the Earth's orbit]; Semiz & Çamlıbel a1412 [Jovian planets]; Lopes & Silk ApJ(15)-a1507 [nearby stars]; Campante et al IAU-a1602 [asteroseismology of red-giant stars].
@ Superfluids: Chiao JMO(06)qp-conf [charged superfluids]; Singh et al a1606 [superfluid 4He].
@ Electric circuits: Fortini et al AP(96)gq/98; Gulian et al a1612 [conversion into electric current].
@ Related topics: Anandan PLA(85) [using superconducting circuits]; Maggiore gq/98 [hep]; Karim gq/02 [compact detector??]; Brodin & Marklund CQG(03) [cavity electromagnetic waves]; Lesovik et al PRD(05)ap [light phase modulation]; Chiao IJMPD(08)gq/06-proc + gq/06-ch, gq/07, a0904 ["Millikan oil drops"]; Daishev et al gq/06 [Dulkyn project]; Cruise CQG(12) [possibilities for very high-frequency gravitational-wave detection]; Arvanitaki & Geraci PRL(13) [optically levitated particles]; Harms et al PRD(13)-a1308 [low-frequency ground-based detector concepts]; Aoyama et al PRD(14)-a1402 [amplitude upper limit around 0.1 Hz from the GPS]; Sabín et al NJP(14)-a1402 + news ns(14)mar [using a Bose-Einstein condensate]; > s.a. torsion in physical theories.

References > s.a. radiation.
@ General references: Saulson AJP(97)jun [II]; Garfinkle AJP(06)mar-gq/05; Leclerc gq/06; Faraoni GRG(07)gq; Corda a0706-wd; Koop & Finn PRD(14)-a1310 [detector response in terms of spacetime Riemann curvature]; Geshnizjani & Kinney JCAP(15)-a1410 [theoretical implications for cosmology]; Królak & Patil Univ(17)-a1708 [the first detection].
@ Elementary: Davies 80; Shapiro et al AS(85); Abrahams & Shapiro ThSc(90)jul; NS(90)sep1, 30-34; Ruthen SA(92)mar; Schäfer & Schutz PW(96); Bartusiak 00; Caldwell & Kamionkowski SA(01)jan; Gibbs SA(02)apr; Shawhan AS(04); Chaudhuri a1605; Lincoln & Stuver TPT(16)oct [history].
@ Reviews: Braginsky & Rudenko PRP(78); Douglass & Braginsky in(79); Thorne RMP(80); Tinto AJP(88)dec; Grishchuk SPU(88); Schutz CQG(89); Blair ed-91; Thorne gq/95, in Böhringer 95 (Texas XVII), gq/97; Ju & Blair IJMPD(96); Flanagan gq/98-GR15; Ricci CP(98); Finn et al AIP(99)gq; Grishchuk et al SPU(01)ap/00; Sathyaprakash Pra(01)gq/00-proc; Finn AIP(01)gq; Harry et al PRD(02)gq/01 [comparison]; Lobo LNP-gq/02; Bezrukov et al gq/04-proc; Hough et al JPB(05)gq; Aufmuth & Danzmann NJP(05); Hogan a0709-in [future]; Kokkotas RMA(08)-a0809; Fairhurst et al GRG(11)-a0908; Andersson PPNP(11)-a1012 [gravitational-wave astronomy]; issue GRG(11)#2 [third-generation gravitational-wave observatories]; Dhurandhar BASI-a1104; Cornish PTRS(13)-a1204; Blair et al a1602; Congedo a1701-proc.
@ Related topics: Rizzi GRG(02) [spacetime stretching]; Fargion CJAA(06)ap/04-conf [tsunamis]; Collins 04 [history, sociology]; > s.a. electromagnetic waves [memory].


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