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تسجيل مستخدم جديدShadowless rapidly rotating yet not ultraspinning Kerr-(Newman)-AdS$_4$ Black Hole
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We show that the Kerr-(Newman)-AdS$_4$ black hole will be shadowless if its rotation parameter is larger than a critical value $a_c$ which is not necessarily equal to the AdS radius. This is because the null hypersurface caustics (NHC) appears both inside the Cauchy horizon and outside the event horizon for the black hole with the rotation parameter beyond the critical value, and the NHC outside the event horizon scatters diffusely the light reaching it. Our studies also further confirm that whether an ultraspinning black hole is super-entropic or not is unrelated to the existence of the NHC outside the event horizon.
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