![]() ![]() To address this problem we have developed a GR ray-tracing code, PyHole, that can simulate the motion of light on the curved KBHSH background. In such cases the black hole solution will be characterised by additional parameters and one may ask whether, again, through direct observations of the black hole, one can measure its parameters and thereby discern a departure from the Kerr class of solutions. KBHsSH are rotating black hole solutions to GR coupled to a massive, complex, scalar field that satisfies a certain synchronicity condition this framework permits non-trivial, long-lived, configurations of fields around black holes that break black hole uniqueness without invoking higher dimensions or different asymptotics. Project Goals and MethodologyĪn initial goal of this project is to study the shadows of a recently discovered class of black hole solutions, referred to as Kerr Black Holes with Scalar Hair (KBHsSH), with a view towards developing templates for use in experiments such as the Event Horizon Telescope. As a result, an observation of the galactic core which reveals a shadow will signal the existence of a black hole, and then the precise form of the shadow can be matched against templates to discriminate between different candidate black hole solutions. This black hole shadow has been shown to encode the parameters of the solution, much as the ringdown signal does in GW observations, and shadow templates have been generated for a number of different black holes. ![]() The objective with this option is to resolve the ‘shadow’ that the event horizon of a black hole - should there be one - casts due to the strong bending of light by its gravitational field. Ī second option, and the focus of this project, makes use of radio astronomy to get an image of the galactic center as the processes that lead to electromagnetic radiation are different to those that drive gravitational radiation these two approaches are, in a sense, complementary. Remarkably, an observation of just this kind was managed by the aLIGO team in their detection of a GW signal from the merger of compact binary GW150914. Hence an observation of the GW radiation from the end stages of a merger process is expected to provide a "smoking gun" for the existence of black holes. These characteristic modes are modeled using perturbation theory in General Relativity, and their structure encodes properties of the solution - including the (non)existence of a horizon. These final waves are known as the ringdown signal and their spectrum is believed to coincide with the characteristic oscillation modes of the remnant. There will be GW emission throughout this process as the objects inspiral and merge, and also by the remnant object as it relaxes towards an equilibrium. In this case we are primarily interested in observing the gravitational waves emitted during and after the merger of two compact massive objects. One option is to make use of gravitational wave (GW) astronomy. ![]() This would require a probe of the horizon-scale structure of the dark central object. Given that the defining characteristic of a black hole is the existence of an event horizon, a direct observation - or lack thereof - of such a structure could fill this gap. Nevertheless, alternative solutions have been proposed, and unambiguous proof that the central object is a black hole has been lacking. These studies indicate that there are dark objects at the center of galaxies with parameters, mass and angular momentum, that make it difficult to imagine viable alternatives to a black hole. Evidence supporting the existence of black holes has come in the form of spectroscopic and proper motion studies of galactic nuclei.
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