446 citations · 2.1k across the 37 of their papers we have counts for
15 papers · 1 filter
Collisional heating as the origin of filament emission in galaxy clusters
G. J. Ferland, A. C. Fabian, N. A. Hatch +4
[Abridged] Photoionization, whether by starlight or other sources, has difficulty in accounting for the observed spectra of the optical filaments that often surround central galaxi…
The origin of molecular hydrogen emission in cooling-flow filaments
G. J. Ferland, A. C. Fabian, N. A. Hatch +4
The optical filaments found in many cooling flows in galaxy clusters consist of low density ($\sim 10^3 \pcc$) cool ( K) gas surrounded by significant amounts of cosmic-…
Merged ionization/dissociation fronts in planetary nebulae
William J. Henney, R. J. R. Williams, Gary J. Ferland +2
The hydrogen ionization and dissociation front around an ultraviolet radiation source should merge when the ratio of ionizing photon flux to gas density is sufficiently low and the…
A Mass Measurement for the Missing Baryons in the Warm-Hot Intergalactic Medium via the X-ray Forest
F. Nicastro, S. Mathur, M. Elvis +7
Recent Cosmological measurements indicate that baryons comprise about four percent of the total mass-energy density of the Universe, which is in accord with the predictions arising…
INTEGRAL Spectrometer SPI's GRB detection capabilities. GRBs detected inside SPI's FoV and with the anticoincidence system ACS
A. von Kienlin, V. Beckmann, A. Rau +15
The spectrometer SPI, one of the two main instruments of the INTEGRAL spacecraft, offers significant gamma-ray burst detection capabilities. In its 35 deg (full width) field of vie…
Instabilities in two-fluid magnetized media with inter-component drift
P. V. Tytarenko, R. J. R. Williams, S. A. E. G. Falle
We analyse the stability of a magnetized medium consisting of a neutral fluid and a fluid of charged particles, coupled to each other through a drag force and exposed to differenti…
Resolved shocks in clumpy media
R. J. R. Williams, J. E. Dyson
We study the structure of shocks in clumpy media, using a multifluid formalism. As expected, shocks broaden as they weaken: for sufficiently weak shocks, no viscous subshock appear…
Hydrodynamics of photoionized columns in the Eagle Nebula, M 16
R. J. R. Williams, D. Ward-Thompson, A. P. Whitworth
We present hydrodynamical simulations of the formation, structure and evolution of photoionized columns, with parameters based on those observed in the Eagle Nebula. On the basis o…
Magnetic ionization fronts II: Jump conditions for oblique magnetization
R. J. R. Williams, J. E. Dyson, T. W. Hartquist
We present the jump conditions for ionization fronts with oblique magnetic fields. The standard nomenclature of R- and D-type fronts can still be applied, but in the case of obliqu…
Symbiotic starburst-black hole AGN -- I. Isothermal hydrodynamics of the mass-loaded ISM
R. J. R. Williams, A. C. Baker, J. J. Perry
Compelling evidence associates the nuclei of active galaxies and massive starbursts. The symbiosis between a compact nuclear starburst stellar cluster and a massive black hole can…
Jet-cloud interations and the brightening of the narrow line region in Seyfert galaxies
W. Steffen, J. L. Gomez, A. C. Raga +1
We study the kinematical and brightness evolution of emission line clouds in the narrow line region (NLR) of Seyfert galaxies during the passage of a jet. We derive a critical dens…
Clumpy ultracompact HII regions -- III. Cometary morphologies around stationary stars
R. J. R. Williams, J. E. Dyson, M. P. Redman
Cometary ultracompact HII regions have been modelled as the interaction of the hypersonic wind from a moving star with the molecular cloud which surrounds the star. We here show th…
Clumpy ultracompact HII regions -- II. Cores, spheres and shells from subsonic flows
M. P. Redman, R. J. R. Williams, J. E. Dyson
We have modelled ultracompact HII regions (UCHIIR) in terms of steady subsonic ionized flows in a clumpy medium. Mass loss from neutral clumps allows the regions to be long-lived.…
Breaking the sound barrier in recombination fronts
R. J. R. Williams, J. E. Dyson
We exploit a generic instability in the integration of steady, sonic, near-isothermal flows to find the complete transition diagram for recombination fronts (for a model system of…
Clumpy Ultracompact HII Regions I: Fully Supersonic Wind-blown Models
J. E. Dyson, R. J. R. Williams, M. P. Redman
We propose that a significant fraction of the ultracompact HII regions found in massive star-forming clouds are the result of the interaction of the wind and ionizing radiation fro…