Do you want to publish a course? Click here

Rotating hybrid axion-miniboson stars

164   0   0.0 ( 0 )
 Added by Yongqiang Wang
 Publication date 2021
  fields Physics
and research's language is English




Ask ChatGPT about the research

We construct rotating hybrid axion-miniboson stars (RHABSs), which are asymptotically flat, stationary, axially symmetric solutions of (3+1)-dimensional Einstein-Klein-Gordon theory. RHABSs consist of a axion field (ground state) and a free complex scalar field (first excited state). The solutions of the RHABSs have two types of nodes, including $^1S^2S$ state and $^1S^2P$ state. For different axion decay constants $f_a$, we present the mass $M$ of RHABSs as a function of the synchronized frequency $omega$, as well as the nonsynchronized frequency $omega_2$, and explore the mass $M$ versus the angular momentum $J$ for the synchronized frequency $omega$ and the nonsynchronized frequency $omega_2$ respectively. Furthermore, we study the effect of axion decay constant $f_a$ and scalar mass $mu_2$ on the existence domain of the synchronized frequency $omega$.



rate research

Read More

We study the Vainshtein mechanism in the context of slowly rotating stars in scalar-tensor theories. While the Vainshtein screening is well established for spherically symmetric spacetimes, we examine its validity in the axisymmetric case for slowly rotating sources. We show that the deviations from the general relativity solution are small in the weak-field approximation outside the star: the solution for the frame-dragging function is the same as in general relativity at leading order. Moreover, in most cases the corrections are suppressed by powers of the Vainshtein radius provided that the screening operates in spherical symmetry. Outside the Vainshtein radius, the frame dragging function receives corrections that are not suppressed by the Vainshtein radius, but which are still subleading. This suggests that the Vainshtein mechanism in general can be extended to slowly rotating stars and that it works analogously to the static case inside the Vainshtein radius. We also study relativistic stars and show that for some theories the frame-dragging function in vacuum does not receive corrections at all, meaning that the screening is perfect outside the star.
In this paper, we construct rotating boson stars composed of the coexisting states of two scalar fields, including the ground and first excited states. We show the coexisting phase with both the ground and first excited states for rotating multistate boson stars. In contrast to the solutions of the nodeless boson stars, the rotating boson stars with two states have two types of nodes, including the $^1S^2S$ state and the $^1S^2P$ state. Moreover, we explore the properties of the mass $M$ of rotating boson stars with two states as a function of the synchronized frequency $omega$, as well as the nonsynchronized frequency $omega_2$. Finally, we also study the dependence of the mass $M$ of rotating boson stars with two states on angular momentum for both the synchronized frequency $omega$ and the nonsynchronized frequency $omega_2$.
We study isotropic and slowly-rotating stars made of dark energy adopting the extended Chaplygin equation-of-state. We compute the moment of inertia as a function of the mass of the stars, both for rotating and non-rotating objects. The solution for the non-diagonal metric component as a function of the radial coordinate for three different star masses is shown as well. We find that i) the moment of inertia increases with the mass of the star, ii) in the case of non-rotating objects the moment of inertia grows faster, and iii) the curve corresponding to rotation lies below the one corresponding to non-rotating stars.
Motivated by possible existence of stringy axions with ultralight mass, we study the behavior of an axion field around a rapidly rotating black hole (BH) obeying the sine-Gordon equation by numerical simulations. Due to superradiant instability, the axion field extracts the rotational energy of the BH and the nonlinear self-interaction becomes important as the field grows larger. We present clear numerical evidences that the nonlinear effect leads to a collapse of the axion cloud and a subsequent explosive phenomena, which is analogous to the bosenova observed in experiments of Bose-Einstein condensate. The criterion for the onset of the bosenova collapse is given. We also discuss the reason why the bosenova happens by constructing an effective theory of a wavepacket model under the nonrelativistic approximation.
We obtain rotating black hole solutions to the novel 3D Gauss-Bonnet theory of gravity recently proposed. These solutions generalize the BTZ metric and are not of constant curvature. They possess an ergoregion and outer horizon, but do not have an inner horizon. We present their basic properties and show that they break the universality of thermodynamics present for their static charged counterparts, whose properties we also discuss. Extending our considerations to higher dimensions, we also obtain novel 4D Gauss-Bonnet rotating black strings.
comments
Fetching comments Fetching comments
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا