We comprehensively model the X-ray luminosity emergent from time dependent relativistic accretion discs, developing analytical models of thermal disc systems as a function black hole mass $M$, $M_d$, and $\alpha$-parameter. The properties these solutions will be directly relevant for understanding TDE observations. demonstrate an extremely strong suppression large holes, $L_X \sim \exp(-m^{7/6}...

We present optical follow-up observation results of three binary black hole merger (BBH) events, GW190408_181802, GW190412, and GW190503_185404, which were detected by the Advanced LIGO Virgo gravitational wave (GW) detectors. Electromagnetic (EM) counterparts are generally not expected for BBH events. However, some theoretical models suggest that EM can possibly arise in special environments, ...

The construction of gravitational wave observatories is one of the greatest scientific efforts of our time. As a result, there is presently a strong need to numerically simulate the emission of gravitation radiation from massive astronomical events such as black hole collisions. This entails the numerical solution of the Einstein field equations. We briefly describe the field equations in their...

We present results of numerical simulations of sequences of binary-single scattering events of black holes in dense stellar environments. The simulations cover a wide range of mass ratios from equal mass objects to 1000:10:10 M⊙ and compare purely Newtonian simulations to simulations in which Newtonian encounters are interspersed with gravitational wave emission from the binary. In both cases, ...

The nature of fast radio bursts (FRBs) remains enigmatic. Highly energetic radio pulses of millisecond duration, FRBs are observed with dispersion measures consistent with an extragalactic source. A variety of models have been proposed to explain their origin. One popular class of theorized FRB progenitor is the coalescence of compact binaries composed of neutron stars and/or black holes. Such ...

Shine a flashlight on a black hole, and one is greeted with the return of a series of concentric rings of light. For a point source of light, and for perfect alignment of the lens, source, and observer, the rings are of infinite brightness (in the limit of geometric optics). In this manner, distant black holes can be revealed through their reflection of light from the Sun. Such retro-MACHO even...

In TeV scale unification models, gravity propagates in 4+δ dimensions while gauge and matter fields are confined to a four dimensional brane, with gravity becoming strong at the TeV scale. For a such scenario, we study strong gravitational interactions in a effective Schwarzschild geometry. Two distinct regimes appear. For large impact parameters, the ratio ρ ∼ (Rs/r0) , (with Rs the Schwarzsch...

Sediment stratigraphy and diatom succession were studied in an 80.5-cm core taken from the deepest part of Third Sister Lake, a small kettle hole in a recently urbanized landscape of southeastern Michigan. Alternating light clay and dark organic bands documented sporadic inputs of clay from outside the basin during rain events, rather than annual laminations. Urban construction activity also di...