Black hole Meissner effect and entanglement

Extremal black holes tend to expel magnetic and electric fields. Fields are unable to reach the horizon because the length of the black hole throat blows up in the extremal limit. The length of the throat is related to the amount of entanglement between modes on either side of the horizon. So it is natural to try to relate the black hole Meissner effect to entanglement. We derive the black hole Meissner effect directly from the low temperature limit of two-point functions in the Hartle-Hawking vacuum. Then we discuss several new examples of the black hole Meissner effect, its applications to astrophysics, and its relationship to gauge invariance

BMS invariance and the membrane paradigm

The Bondi-van der Burg-Metzner-Sachs (BMS) group is the asymptotic symmetry group of asymptotically flat spacetime. It is infinite dimensional and entails an infinite number of conservation laws. According to the black hole membrane paradigm, null infinity (in asymptotically flat spacetime) and black hole event horizons behave like fluid membranes. The fluid dynamics of the membrane is governed by an infinite set of symmetries and conservation laws. Our main result is to point out that the infinite set of symmetries and conserved charges of the BMS group and the membrane paradigm are the same. This relationship has several consequences. First, it sheds light on the physical interpretation of BMS conservation laws. Second, it generalizes the BMS conservation laws to arbitrary subregions of arbitrary null surfaces. Third, it clarifies the identification of the superrotation subgroup of the BMS group. We briefly comment on the black hole information problem.Comment: 16 pages, 1 figur

Stromal cell effects on melanoma cell drug response

Thesis (M.A.)--Boston UniversityObjective: Melanoma is currently one of the deadliest forms of skin disease in the United States. However in the past decade there have been significant advances in treatment. Among the most promising recent developments, inhibitors of the serine/threonine-protein kinase B-Raf (BRAF inhibitors) such as vemurafenib show great promise and have been shown to increase the median survival of patients with melanoma cells that harbor a mutation of the BRAF gene. While BRAF inhibitors and other treatment therapies have much potential, more needs to be done to improve treatment. As with other cancers, a major hurdle in the treatment of melanoma is the eventual tumor resistance to drug therapy. Accessory cells are thought to play a large role in mediating tumor resistance to drug treatment. Stromal cells have been known to release cytokines and growth factors that aid in cancer proliferation. They can also expression adhesion molecules that further help to aid cell growth and tumor development. It has also been demonstrated that these accessory cells can significantly alter cancer cell drug response as a result of the factors they release or express on their surface. In this study we hypothesize that certain anti-cancer drugs will behave differently against melanoma cell line A375 in the presence versus the absence of stromal cells. Methods: Melanoma cell line A375 was grown on 384 well plates in the presence or absence of different stromal cell lines. A number of different drugs were screened using Compartment-Specific Bioluminescence Imaging to determine if there was a difference in A375 proliferation after drug treatment in the presence versus absence of accessory cells. After an initial screen, a few drugs were chosen to generate dose-response curves to determine if different drugs had different effects at various doses in the presence or absence of stromal cells. [TRUNCATED

Black hole jet power from impedance matching

Black hole jet power depends on the angular velocity of magnetic field lines, $\Omega_F$. Force-free black hole magnetospheres typically have $\Omega_F/\Omega_H \approx 0.5$, where $\Omega_H$ is the angular velocity of the horizon. We give a streamlined proof of this result using an extension of the classical black hole membrane paradigm. The proof is based on an impedance-matching argument between membranes at the horizon and infinity. Then we consider a general relativistic magnetohydrodynamic simulation of an accreting, spinning black hole and jet. We find that the theory correctly describes the simulation in the jet region. However, the field lines threading the horizon near the equator have much smaller $\Omega_F/\Omega_H$ because the force-free approximation breaks down in the accretion flow.Comment: 8 pages, 8 figures, updated to match Phys. Rev. D versio

Energy extraction from boosted black holes: Penrose process, jets, and the membrane at infinity

Numerical simulations indicate that black holes carrying linear momentum and/or orbital momentum can power jets. The jets extract the kinetic energy stored in the black hole's motion. This could provide an important electromagnetic counterpart to gravitational wave searches. We develop the theory underlying these jets. In particular, we derive the analogues of the Penrose process and the Blandford-Znajek jet power prediction for boosted black holes. The jet power we find is $(v/2M)^2 \Phi^2/(4\pi)$, where $v$ is the hole's velocity, $M$ is its mass, and $\Phi$ is the magnetic flux. We show that energy extraction from boosted black holes is conceptually similar to energy extraction from spinning black holes. However, we highlight two key technical differences: in the boosted case, jet power is no longer defined with respect to a Killing vector, and the relevant notion of black hole mass is observer dependent. We derive a new version of the membrane paradigm in which the membrane lives at infinity rather than the horizon and we show that this is useful for interpreting jets from boosted black holes. Our jet power prediction and the assumptions behind it can be tested with future numerical simulations.Comment: 14 pages, 5 figures, updated to match Phys. Rev. D versio

Polarization in a three-dimensional Fermi gas with Rabi coupling

We investigate the polarization of a two-component three-dimensional fermionic gas made of repulsive alkali-metal atoms. The two pseudo-spin components correspond to two hyperfine states which are Rabi coupled. The presence of Rabi coupling implies that only the total number of atoms is conserved and a quantum phase transition between states dominated by spin-polarization along different axses is possible. By using a variational Hartree-Fock scheme we calculate analytically the ground-state energy of the system and determine analytically and numerically the conditions under which there is this quantum phase transition. This scheme includes the well-known criterion for the Stoner instability. The obtained phase diagram clearly shows that the polarized phase crucially depends on the interplay among the Rabi coupling energy, the interaction energy per particle, and the kinetic energy per particle.Comment: 12 pages, 2 figure