Can accretion properties distinguish between a naked singularity, wormhole and black hole?

We first advance a mathematical novelty that the three geometrically and topologically distinct objects mentioned in the title can be exactly obtained from the Jordan frame vacuum Brans I solution by a combination of coordinate transformations, trigonometric identities and complex Wick rotation. Next, we study their respective accretion properties using the Page–Thorne model which studies accretion properties exclusively for $$r\ge r_{\text {ms}}$$ r ≥ r ms (the minimally stable radius of particle orbits), while the radii of singularity/throat/horizon $$r<r_{\text {ms}}$$ r < r ms . Also, its Page–Thorne efficiency $$\epsilon $$ ϵ is found to increase with decreasing $$r_{\text {ms}}$$ r ms and also yields $$\epsilon =0.0572$$ ϵ = 0.0572 for Schwarzschild black hole (SBH). But in the singular limit $$r\rightarrow r_{s}$$ r → r s (radius of singularity), we have $$\epsilon \rightarrow 1$$ ϵ → 1 giving rise to $$100 \%$$ 100 % efficiency in agreement with the efficiency of the naked singularity constructed in [10]. We show that the differential accretion luminosity $$\frac{d{\mathcal {L}}_{\infty }}{d\ln {r}}$$ d L ∞ d ln r of Buchdahl naked singularity (BNS) is always substantially larger than that of SBH, while Eddington luminosity at infinity $$L_{\text {Edd}}^{\infty }$$ L Edd ∞ for BNS could be arbitrarily large at $$r\rightarrow r_{s}$$ r → r s due to the scalar field $$\phi $$ ϕ that is defined in $$(r_{s}, \infty )$$ ( r s , ∞ ) . It is concluded that BNS accretion profiles can still be higher than those of regular objects in the universe.

Accretion disk around the rotating Damour–Solodukhin wormhole

A new rotating generalization of the Damour–Solodukhin wormhole (RDSWH), called Kerr-like wormhole, 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 properties such as the ISCO or marginally stable radius $$r_{\mathrm{ms}}$$rms, efficiency $$\epsilon $$ϵ and the disk potential $$V_{\mathrm{eff}}$$Veff are independent of $$\lambda $$λ (which means they are identical to their KBH counterparts for any given spin). Differences however appear in the emissivity properties for higher values $$0.1<\lambda \le 1$$0.1<λ≤1 (say) and for the extreme spin $$a_{\star }=0.998$$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 $$\varDelta _{\lambda }$$Δλ in the maxima of flux of radiation F(r) shows non-zero values but is too tiny to be observable at present for $$\lambda < 10^{-3}$$λ<10-3 permitted by the strong lensing bound. The broad conclusion is that RDSWH are experimentally indistinguishable from KBH by accretion characteristics.

Properties of strangelets at zero temperature in a new quark mass confinement model

We investigate the properties of strangelets at zero temperature with a new quark model in which the linear confinement and one-gluon-exchange (OGE) interactions are integrated as a whole. The charge, parameters dependence and the stability of strangelets are discussed. Our results showed that the OGE interaction lowers the energy of a strangelet, and consequently makes its stable radius smaller than that in the case of not including this interaction, and less than that of a nucleus with the same baryon number. Therefore, the strangelet in the present model has more chance to be absolutely stable.