|  Black-Hole Uniqueness and Hair | 
No-Hair and Uniqueness Results > s.a. astrophysical tests
  of general relativity; black-hole perturbations; kerr
  spacetime; multipole moments.
  * Idea: "Hair"
    denotes one or more parameters characterizing a black hole that are not
    associated with conserved quantities at infinity; The expression
    "black holes have no hair," introduced by Wheeler, means that a
    stationary black hole is characterized just by the value of those
    multipoles that cannot be radiated away; There are no bifurcations from
    the Kerr-Newman family of solutions; In particular, uniqueness theorems
    prove that there are no other families of solutions of the Einstein equation
    with the same parameters; These are global results, and are shown using
    Green-like identities and integrals.
  * Results: 1984, Established
    first for electrovac solutions; They hold also in scalar-tensor theories
    and supergravity; There are no static, spherically symmetric
    Einstein-Dirac-Maxwell or Einstein-Yang-Mills-Dirac solutions with non-trivial
    spinors; 2015, Extended by Gürlebeck to certain types of astrophysical
    black holes; 2016, Soft-hair results by Hawking, Perry and Strominger.
  * Exceptions: Scalar hair
    in Einstein-Yang-Mills-Higgs systems (but unstable), and higher-curvature
    (Gauss-Bonnet, string inspired) gravity (but no new conserved quantum
    number).
  * No-short-hair theorem:
    If a spherically-symmetric static black hole has hair, then this hair must
    extend beyond 3/2 the horizon radius; The theorem fails beyond the regime
    of spherically-symmetric static black holes.
  @ Books, reviews:
    Mazur in(87)ht/01;
    Chruściel CM(94)gq;
    Bekenstein gq/96-conf;
    Heusler HPA(96)gq,
    96,
    LRR(98);
    Carter gq/97-MG8;
    Chruściel et al LRR(12)-a1205.
  @ General references: Etesi CMP(98)ht/97 [stationary black holes];
    Vigeland PRD(10)-a1008 [multipole moments of bumpy black holes];
    Bhattacharya PRD(13)-a1307 [massive forms and spin-1/2 fields];
    Gürlebeck PRL(15)
    + viewpoint Ashtekar Phy(15)-a1504 [static axisymmetric black holes with surrounding matter].
  @ Gravitational-wave-based tests: 
    Thrane et al PRD(17)-a1706;
    East & Pretorius PRL(17)
      [long-lived hair from superradiant instability, and gravitational-wave signature];
    Carullo et al PRD(18)-a1805 [ringdown phase of binary coalescence];
    Isi et al PRL(19)-a1905 [GW150914];
    Ota & Chirenti PRD(20)-a1911.
  @ Other phenomenology: Lyutikov a1209-proc [astrophysical black holes];
    Johannsen CQG(16)
    + CQG+,
    Cardoso & Gualtieri CQG(16)-a1607 [electromagnetic tests, status];
    Herdeiro & Radu CQG+(17);
    news sn(19)sep [evidence from the ringing of a black hole];
    Allahyari & Shao a2102 [GRO J1655-40].
  @ Extensions: Dobkowski-Ryłko et al PRD(18)-a1803 [local version];
    Barceló et al CQG(19)-a1901 [compact objects without event horizons].
 Related topics: 
  see results and solutions for specific types of hair
  \ black-hole solutions.
 Related topics: 
  see results and solutions for specific types of hair
  \ black-hole solutions.
Modified Theories
  > s.a. scalar-tensor theories; types of black-hole hair.
  * In higher dimensions:
    In more than four dimensions, the conventional uniqueness theorem for
    asymptotically flat spacetimes does not hold, i.e., black objects cannot
    be classified only by their mass, angular momentum and charge.
  @ In general: Ayón-Beato et al PRD(00)gq/99 [metric-affine gravity];
    Vigeland et al PRD(11)-a1102 [bumpy black holes];
    Skákala & Shankaranarayanan PRD(14)-a1312 [Lovelock gravity];
    Sultana & Kazanas GRG(18)-a1810 [in R2 gravity].
  @ Proca field:
    Ayón-Beato in(02)gq;
    Zilhão et al CQG(15)-a1505 [very long-lived Proca field condensates];
    Herdeiro et al CQG(16)-a1603;
    Fan JHEP(16)-a1606.
  @ Higher-dimensional: Mazur & Bombelli JMP(87) [5D Kaluza-Klein theory];
    Gibbons et al PRL(02)gq;
    Kol ht/02;
    Reall PRD(03) [supersymmetric, 5D];
    Rogatko PRD(03)ht,
    PRD(04) [5D sigma-models, stationary],
    PRD(06);
    Hollands et al CMP(07)gq/06 [stationary rotating implies axisymmetric];
    Hollands & Jazadjiev CQG(08) [5D Einstein-Maxwell];
    Hollands & Yazadjiev CMP(11)-a0812 [D-dimensional stationary Kaluza-Klein black holes];
    Figueras & Lucietti CQG(10)-a0906;
    Mizuno et al PRD(10)-a0911 [and Penrose inequality];
    Yazadjiev PRD(10) [5D Einstein-Maxwell gravity],
    JHEP(11)-a1104 [5D Einstein-Maxwell-dilaton gravity];
    Anabalón et al PRD(11)-a1108 [with gravitational hair];
    Hollands CQG(12)-a1204 [uniqueness and new thermodynamic identities in 11D supergravity];
    Hollands & Ishibashi CQG(12)-a1206 [rev].
  @ 5D supergravity: Gutowski JHEP(04)ht;
    Tomizawa et al PRD(09)-a0901;
    Armas & Harmark JHEP(10) [multiple disconnected horizons];
    Tomizawa PRD(10)-a1007.
  @ Generalized no-hair / uniqueness theorems: Wells gq/98 [superstring black holes];
    Hod PRD(16)-a1612 [spherically symmetric reflecting stars].
  @ Hairy situations: Dubovsky et al JHEP(07)-a0706 [Lorentz-violating theories of massive gravity];
    Brito et al PRD(13)-a1309 [massive graviton hair].
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  send feedback and suggestions to bombelli at olemiss.edu – modified 6 feb 2021