Distinguishing signature of Kerr-MOG black hole and superspinar via Lense–Thirring precession

Abstract We examine the geometrical differences between the black hole (BH) and naked singularity (NS) or superspinar via Lense–Thirring (LT) precession in spinning modified-gravity (MOG). For BH case, we show that the LT precession frequency ( $$\Omega _{LT}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>Ω</mml:mi> <mml:mrow> <mml:mi>LT</mml:mi> </mml:mrow> </mml:msub> </mml:math> ) along the pole is proportional to the angular-momentum ( J ) parameter or spin parameter ( a ) and is inversely proportional to the cubic value of radial distance parameter, and also governed by Eq. (1). Along the equatorial plane it is governed by Eq. (2). While for superspinar , we show that the LT precession frequency is inversely proportional to the cubic value of the spin parameter and it decreases with distance by MOG parameter as derived in Eq. (3) at the pole and in the limit $$a&gt;&gt;r$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>a</mml:mi> <mml:mo>&gt;</mml:mo> <mml:mo>&gt;</mml:mo> <mml:mi>r</mml:mi> </mml:mrow> </mml:math> (where a is spin parameter). For $$\theta \ne \frac{\pi }{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>θ</mml:mi> <mml:mo>≠</mml:mo> <mml:mfrac> <mml:mi>π</mml:mi> <mml:mn>2</mml:mn> </mml:mfrac> </mml:mrow> </mml:math> and in the superspinar limit, the spin frequency varies as $$\Omega _{LT}\propto \frac{1}{a^3\cos ^4\theta }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>Ω</mml:mi> <mml:mrow> <mml:mi>LT</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∝</mml:mo> <mml:mfrac> <mml:mn>1</mml:mn> <mml:mrow> <mml:msup> <mml:mi>a</mml:mi> <mml:mn>3</mml:mn> </mml:msup> <mml:msup> <mml:mo>cos</mml:mo> <mml:mn>4</mml:mn> </mml:msup> <mml:mi>θ</mml:mi> </mml:mrow> </mml:mfrac> </mml:mrow> </mml:math> and by Eq. (38).