Eur. Phys. J. C (2019) 79:952
https://doi.org/10.1140/epjc/s10052-019-7488-7
Regular Article - Theoretical Physics
Accretion disk around the rotating Damour–Solodukhin wormhole
R. Kh. Karimov
1
,R.N.Izmailov
1,a
, K. K. Nandi
1,2
1
Zel’dovich International Center for Astrophysics, Bashkir State Pedagogical University, 3A, October Revolution Street, Ufa 450008, RB, Russia
2
High Energy Cosmic Ray Research Center, University of North Bengal, Darjeeling, WB 734 013, India
Received: 5 October 2019 / Accepted: 12 November 2019 / Published online: 21 November 2019
© The Author(s) 2019
Abstract A new rotating generalization of the Damour–
Solodukhin wormhole (RDSWH), called Kerr-like worm-
hole, has recently been proposed and investigated by Bueno
et al. for echoes in the gravitational wave signal. We show a
novel feature of the RDSWH, viz., that the kinematic prop-
erties such as the ISCO or marginally stable radius r
ms
,effi-
ciency and the disk potential V
eff
are independent of λ
(which means they are identical to their KBH counterparts
for any given spin). Differences however appear in the emis-
sivity properties for higher values 0.1 <λ≤ 1 (say) and for
the extreme spin a
= 0.998. The kinematic and emissivity
are generic properties as variations of the wormhole mass
and the rate of accretion within the model preserve these
properties. Specifically, the behavior of the luminosity peak
is quite opposite to each other for the two objects, which
could be useful from the viewpoint of observations. Apart
from this, an estimate of the difference Δ
λ
in the maxima of
flux of radiation F(r) shows non-zero values but is too tiny
to be observable at present for λ<10
−3
permitted by the
strong lensing bound. The broad conclusion is that RDSWH
are experimentally indistinguishable from KBH by accretion
characteristics.
1 Introduction
There is a renewed interest in wormholes after it has been
realized that they can mimic post-merger ring-down ini-
tial quasi-normal mode (QNM) spectrum of gravitational
waves. To our knowledge, this possibility of “wormhole
QNM mode” was first put forward by Damour and Solo-
dukhin [1], where resonances were trapped in a double-
hump potential associated with what they termed “black
hole foil”. This is an example of a horizonless wormhole
a
e-mail: izmailov.ramil@gmail.com
more commonly known as the Damour–Solodukhin worm-
hole (DSWH). The DSWH differs from the Schwarzschild
black hole (SBH) by a dimensionless real deviation parame-
ter λ and represents a twice-asymptotically flat regular space-
time connected by a throat. The authors showed that if λ is
so small that the time scale Δt = 2GM ln
1
λ
2
is longer
than the observational time scale, the signals emitted by a
source falling into a wormhole will contain the usual QNM
ringing signature of a black hole, in spite of the absence of
a true horizon [1]. Völkel and Kokkotas [2] have recently
shown, using an inverse method, that the knowledge of the
observed QNM spectrum can allow one to also accurately
construct the double hump Pöschl–Teller potential approxi-
mating that of DSWH. Bueno et al. [3] suitably redefined the
static DSWH and further generalized it the into a Kerr-like
wormhole, called here the rotating DSWH or RDSWH for
brevity. They studied its gravitational wave echo properties.
Gravitational deflection of relativistic massive particles by
RDSWH has been recently studied by Jusufi et al. [4].
QNM ringing by BHs have been well reviewed, see, e.g.
Bertietal.[5] but ringing by WHs still remained an open
question. A first step towards answering the question was
initiated by Cardoso et al. [6,7], who studied the QNM ring-
ing using a wormhole assembled by means of Visser’s cut-
and-paste surgery of two copies of Schwarzschild black holes
(SBH) at a radius close to the horizon [8] (For future perspec-
tives and new directions of research on ultracompact objects
(UCO) including wormholes, see [9]). The authors of [8]
showed that, while the time evolution of the early QNMs
accurately mimic those from SBH horizon, the differences (if
any) would appear only at later times. This work inspired an
investigation in [10], where it has been shown that the mass-
less Ellis–Bronnikov wormhole (EBWH) [11–13], made of
the minimally coupled exotic scalar field, can also reproduce
the black hole QNM spectrum in the eikonal limit (large
). Ringing by massive EBWH was studied in [14]. These
developments prompt a natural inquiry as to whether static
DSWH can exhibit mimicking of SBH in other phenomenon
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