Types of Gravitational Lensing  

Microlensing > s.a. cosmic-string phenomenology; dark matter and dark-matter types [MACHOs]; extrasolar systems [planets].
* Idea: Gravitational lensing by small objects such as planets; Gives very small image separation (< 1 mas) but brighter images.
* Applications: It has been used to search for MACHOs and exoplanets (one tends to find more outer planets than with Doppler shifts or transits, the presence of a bright star not needed, and one can measure the mass without seeing the planet); It provides a way to measure the mass (and spectra) of isolated stars.
* History: 1936, Paper by Einstein & R W Mandl (Czech engineer who prodded him); 1964, Liebes PP, Refsdal MNRAS; 1986, Paczyński proposed use for dark matter detection; 1998, 1-m telescopes start looking; 1999, Planet around a binary system found with it.
@ Reviews, intros: Paczyński & Wambsganss PW(93)may; Evans ap/96-proc; Gould ap/96-conf, ASP-ap/00; Roulet & Mollerach PRP(97); Mao ap/99-conf; Paczyński ASP-ap/99; Sackett ASP-ap/00; Evans ap/03-in; Paczyński ap/03 [and future]; Rattenbury MPLA(06) [planetary]; Zakharov ap/06-ln; Gould a0803-conf; Mao a0811-conf; Moniez GRG(10)-a1001; Bozza et al ed-a1102; Mao RAA(12)-a1207 [astrophysical applications]; Jetzer a1304-proc; Rahvar IJMPD(15)-a1503.
@ Theory, formalism: Gould ApJ(00)ap; Asada ApJ(02)ap [perturbative]; Petters et al JMP(09)-a0807, JMP(09) [stochastic]; Gould a1312/ApJ [effective timescale]; Nucita et al IJMPD(17)-a1705 [astrometric microlensing].
@ Of gravitational waves: Bar-Kana PRD(96)ap [limits on background]; De Paolis et al A&A(01)ap/00; Smith et al MNRAS(18)-a1707 [and the 2015 detections].
@ By cosmic strings: Kuijken et al MNRAS(08)-a0707; Bloomfield & Chernoff PRD(14)-a1311 [cosmic-string loops].
@ Related topics: Gould ap/96-conf [imaging binaries, quasars]; Jetzer HPA(96)ap, ap/97-MG8 [dark matter search]; MACHO collab ap/97-proc [data]; Paczyński ApJL(98)ap/97 [SIM plans]; Han et al MNRAS(00)ap/99, ApJ(04)ap/03 [free-floating planets]; Smith et al MNRAS(03)ap/02 [acceleration and parallax effects]; Jetzer a1001-MG12, a1304-MG13 [by galactic globular clusters]; Gaudi a1002-ch [by exoplanets]; Carlip a1505 [by vacuum fluctuations?]; Gould JKAS(16)-a1603 [by Kuiper, Oort, and free-floating planets]; Mavromatos & Papavassiliou EPJC(18)-a1712 [global monopoles].

Weak Lensing > s.a. cosmological tests; neutrino astrophysics.
* Idea: Gravitational lensing that produces a small distorsion in images of background galaxies; It cannot be recognized as lensing on the basis of a single galaxy image, but one uses the statistical properties of many galaxies in a region of the sky.
* Surveys: Weak lensing surveys look for cosmic shear and mostly probe the dark matter distribution; 2018, Results from the first year of Dark Energy Survey data show that weak lensing can probe cosmological parameters with a precision comparable to that of cosmic microwave background observations.
@ General references: Bartelmann & Schneider PRP(01); Mellier & van Waerbeke CQG(02)in; Hoekstra a1312-ln; Alsing et al MNRAS(15)-a1410; Clarkson JCAP(15)-a1503 [general theory, distortions]; Bartelmann & Maturi a1612-en [rev]; Slosar Phy(18) [rev of survey results].
@ In various gravity theories: Acquaviva et al PRD(04)ap, IAU(04)ap; Song & Doré JCAP(09) [test of general relativity vs f(R) theories]; Hearin & Zentner JCAP(09) [gravity tests and galaxy-formation physics]; Horváth et al PRD(13) [in fourth-order gravity]; Higuchi & Shirasaki MNRAS(16)-a1603 [f(R) gravity].
@ And cmb: Hanson et al GRG(10)-a0911, Merkel & Schäfer MNRAS(11)-a1007 [lensing of cmb]; news pt(11)aug [lensing]; Madhavacheril et al PRL(15) + Stompor Phy(15)apr [by dark-matter halos]; Lee a1510 [cross-correlation]; Marozzi et al JCAP(16)-a1605 [beyond the Born approximation].
@ In cosmology: Massey et al ap/04-conf [dark matter and dark energy]; Munshi et al PRP(08), Hoekstra & Jain ARNPS(08)-a0805 [rev]; Song & Doré JCAP(09)-a0812 [and redshift surveys]; Kainulainen & Marra PRD(09)-a0909 [cumulative, stochastic approach]; Jullo et al MNRAS(14)-a1309 [and galaxy-cluster reconstruction]; Mandelbaum IAU(15)-a1410 [galaxy halo masses]; Fleury et al JCAP(15)-a1508, Fleury a1511-PhD [stochastic]; Ammazzalorso et al PRL(20) [cross-correlation with γ rays, and dark matter distribution].

Types of Spacetimes > see cosmic-string phenomenology; lensing in specific models.

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