We study late-time behaviors of massive scalar fields in general static and spherically symmetric extremal black hole spacetimes in arbitrary dimensions. We show the existence of conserved quantities on the extremal black hole horizons for specific mass squared and multipole modes of the scalar fields. Those quantities on the horizon are called the Aretakis constants and are constructed from the higher-order derivatives of the fields. Focusing on the region near the horizon at late times, where is well approximated by the near-horizon geometry, we show that the leading behaviors of the fields are described by power-law tails. The late-time power-law tails lead to the Atetakis instability: blowups of the transverse derivatives of the fields on the horizon. We further argue that the Aretakis constants and instability correspond to respectively constants and blowups of components of covariant derivatives of the fields at the late time in the parallelly propagated null geodesic frame along the horizon. We finally discuss the relation between the Aretakis constants and ladder operators constructed from the approximate spacetime conformal symmetry near the extremal black hole horizons.
I. INTRODUCTIONExtremal black holes have long played an important role in various aspects. They have zero Hawking temperature and are expected to bring us valuable insights into the black hole thermodynamics [1-6] and the Hawking radiation [7,8]. In the context of astrophysics, it is suggested that many astrophysical black holes are nearly extremal [9-13], and high energy phenomena around such black holes are discussed, e.g., in [14][15][16]. For understanding the nature of the extremal black holes, it is important to investigate the dynamical properties of test fields and particles around them.Aretakis [17,18] has discussed late-time behaviors of test massless scalar fields in fourdimensional extremal Reissner-Nordström black holes. When generic initial data are given on an initial hypersurface crossing the horizon, he argued that the higher-order transverse derivatives of the fields blow up polynomially in time, not exponential, on the event horizon, while they decay outside the horizon. This blowup on the horizon is called the Aretakis instability. The occurrence of the Aretakis instability is associated with the fact that latetime behaviors of fields are described by power-law tails [19][20][21][22][23][24], not the exponential decay in time. The instability also occurs against vector, tensor, and massive or charged scalar fields [19,25,26], and in other spacetimes such as extremal Kerr(-Newman) [25,27], extremal Bañados-Teitelboim-Zanelli [28], and two-dimensional anti-de Sitter spacetimes (AdS 2 ) [19, 29, 30] 1 , and in higher dimensions [31]. The nonlinear evolution of the Aretakis instability has been investigated in [32][33][34].Related to the Aretakis instability, conserved quantities along the horizons, which are constructed from the higher-order radial derivatives of the fields, are studied [17,18]. These conserved quantitie...