ASTROPHYSICAL JOURNAL 793 (2014) ARTN 51
Phase-space Lagrangian derivation of electrostatic gyrokinetics in general geometry (vol 53, 045001, 2011)
PLASMA PHYSICS AND CONTROLLED FUSION 56 (2014) ARTN 099501
PLASMA PHYSICS AND CONTROLLED FUSION 56 (2014) ARTN 129501
NATURE PHYSICS 10 (2014) 520-524
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 445 (2014) 3133-3151
Classical and Quantum Gravity 31 (2014)
© 2014 IOP Publishing Ltd.We consider the problem of star consumption by supermassive black holes in non-spherical (axisymmetric, triaxial) galactic nuclei. We review the previous studies of the loss-cone problem and present a novel simulation method that allows us to separate out the collisional (relaxation-related) and collisionless (related to non-conservation of angular momentum) processes and determine their relative importance for the capture rates in different geometries. We show that for black holes more massive than 107 M⊙, the enhancement of the capture rate in non-spherical galaxies is substantial, with even modest triaxiality being capable of keeping the capture rate at the level of a few percent of black hole mass per Hubble time.
Nature 515 (2014) 85-87
The hot (10(7) to 10(8) kelvin), X-ray-emitting intracluster medium (ICM) is the dominant baryonic constituent of clusters of galaxies. In the cores of many clusters, radiative energy losses from the ICM occur on timescales much shorter than the age of the system. Unchecked, this cooling would lead to massive accumulations of cold gas and vigorous star formation, in contradiction to observations. Various sources of energy capable of compensating for these cooling losses have been proposed, the most promising being heating by the supermassive black holes in the central galaxies, through inflation of bubbles of relativistic plasma. Regardless of the original source of energy, the question of how this energy is transferred to the ICM remains open. Here we present a plausible solution to this question based on deep X-ray data and a new data analysis method that enable us to evaluate directly the ICM heating rate from the dissipation of turbulence. We find that turbulent heating is sufficient to offset radiative cooling and indeed appears to balance it locally at each radius-it may therefore be the key element in resolving the gas cooling problem in cluster cores and, more universally, in the atmospheres of X-ray-emitting, gas-rich systems on scales from galaxy clusters to groups and elliptical galaxies.
BUILDING AND ENVIRONMENT 76 (2014) 81-91
Erratum: Long-wavelength limit of gyrokinetics in a turbulent tokamak and its intrinsic ambipolarity (Plasma Phys. Control. Fusion (2012) 54 (115007))
Plasma Physics and Controlled Fusion 56 (2014)
The impact of occupancy patterns, occupant-controlled ventilation and shading on indoor overheating risk in domestic environments
BUILDING AND ENVIRONMENT 78 (2014) 183-198
Monthly Notices of the Royal Astronomical Society 446 (2014) 3150-3161
© 2014 The Authors.We have developed a novel Monte Carlo method for simulating the dynamical evolution of stellar systems in arbitrary geometry. The orbits of stars are followed in a smooth potential represented by a basis-set expansion and perturbed after each timestep using local velocity diffusion coefficients from the standard two-body relaxation theory. The potential and diffusion coefficients are updated after an interval of time that is a small fraction of the relaxation time, but may be longer than the dynamical time. Thus, our approach is a bridge between the Spitzer's formulation of the Monte Carlo method and the temporally smoothed self-consistent field method. The primary advantages are the ability to follow the secular evolution of shape of the stellar system, and the possibility of scaling the amount of two-body relaxation to the necessary value, unrelated to the actual number of particles in the simulation. Possible future applications of this approach in galaxy dynamics include the problem of consumption of stars by a massive black hole in a non-spherical galactic nucleus, evolution of binary supermassive black holes, and the influence of chaos on the shape of galaxies, while for globular clusters it may be used for studying the influence of rotation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 445 (2014) 256-269
PLASMA PHYSICS AND CONTROLLED FUSION 56 (2014) ARTN 095014
Science (New York, N.Y.) 345 (2014) 791-795
The diffuse interstellar bands (DIBs) are absorption lines observed in visual and near-infrared spectra of stars. Understanding their origin in the interstellar medium is one of the oldest problems in astronomical spectroscopy, as DIBs have been known since 1922. In a completely new approach to understanding DIBs, we combined information from nearly 500,000 stellar spectra obtained by the massive spectroscopic survey RAVE (Radial Velocity Experiment) to produce the first pseudo-three-dimensional map of the strength of the DIB at 8620 angstroms covering the nearest 3 kiloparsecs from the Sun, and show that it follows our independently constructed spatial distribution of extinction by interstellar dust along the Galactic plane. Despite having a similar distribution in the Galactic plane, the DIB 8620 carrier has a significantly larger vertical scale height than the dust. Even if one DIB may not represent the general DIB population, our observations outline the future direction of DIB research.
BUILDING AND ENVIRONMENT 78 (2014) 171-182
in Beyond the Second Law Entropy Production and Non-equilibrium Systems, Springer (2014) 15
macroscopic behaviour of a system is irreversible, as embodied in the second law, but the microscopic motion of all of the individual components is fully time reversible. Therefore for any system change, the opposite system change must also ...
THE RELATION BETWEEN GAS DENSITY AND VELOCITY POWER SPECTRA IN GALAXY CLUSTERS: QUALITATIVE TREATMENT AND COSMOLOGICAL SIMULATIONS
ASTROPHYSICAL JOURNAL LETTERS 788 (2014) ARTN L13
BUILDING AND ENVIRONMENT 66 (2013) 72-81
PHYSICS OF PLASMAS 20 (2013) ARTN 056106
ASTROPHYSICAL JOURNAL LETTERS 764 (2013) ARTN L21