We study the long-term thermal stability of radiation dominated disks in which the vertical structure is determined self-consistently by the balance of heating due to dissipation of MHD turbulence driven by the magneto-rotational instability (MRI), and cooling due to radiation emitted at the photosphere. The calculations adopt the local shearing box approximation, and utilize the recently developed radiation transfer module in the Athena MHD code based on a variable Eddington tensor rather than an assumed local closure. After saturation of the MRI, in many cases the disk maintains a steady vertical structure for many thermal times. However, in every case in which the box size in the horizontal directions is at least one pressure scale height, fluctuations associated with MRI turbulence and dynamo action in the disk eventually trigger a thermal runaway which causes the disk to either expand or contract until the calculation must be terminated. During runaway, the dependence of the heating and cooling rates on total pressure satisfy the simplest criterion for classical thermal instability. We identify several physical reasons why the thermal runaway observed in our simulations differ from the standard α disk model, for example the advection of radiation contributes a non-negligible fraction to the vertical energy flux at the largest radiation pressure, most of the dissipation does not happen in the disk mid-plane, and the change of dissipation scale height with mid-plane pressure is slower than the change of density scale height. We discuss how and why our results differ from those published previously. Such thermal runaway behavior might have important implications for interpreting temporal variability in observed systems, but fully global simulations are required to study the saturated state before detailed predictions can be made.

We use global three dimensional radiation magneto-hydrodynamical simulations to study accretion disks onto a 5 × 10 8 M black hole with accretion rates varying from ∼ 250L Edd /c 2 to 1500L Edd /c 2 . We form the disks with torus centered at 50 − 80 gravitational radii with self-consistent turbulence initially generated by the magneto-rotational instability. We study cases with and without net vertical magnetic flux. The inner regions of all disks have radiation pressure ∼ 10 4 −10 6 times the gas pressure. Non-axisymmetric density waves that steepen into spiral shocks form as gas flows towards the black hole. In simulations without net vertical magnetic flux, Reynolds stress generated by the spiral shocks are the dominant mechanism to transfer angular momentum. Maxwell stress from MRI turbulence can be larger than the Reynolds stress only when net vertical magnetic flux is sufficiently large. Outflows are formed with speed ∼ 0.1 − 0.4c. When the accretion rate is smaller than ∼ 500L Edd /c 2 , outflows start around 10 gravitational radii and the radiative efficiency is ∼ 5% − 7% with both magnetic field configurations. With accretion rate reaching 1500L Edd /c 2 , most of the funnel region close to the rotation axis becomes optically thick and the outflow only develops beyond 50 gravitational radii. The radiative efficiency is reduced to 1%. We always find the kinetic energy luminosity associated with the outflow is only ∼ 15% − 30% of the radiative luminosity. The mass flux lost in the outflow is ∼ 15% − 50% of the net mass accretion rates. We discuss implications of our simulation results on the observational properties of these disks.

Using Hubble Space Telescope observations of 147 host galaxies of low-mass black holes (BHs), we systematically study the structures and scaling relations of these active galaxies. Our sample is selected to have central BHs with virial masses of ∼10 5 -10 6 M . The host galaxies have total I-band magnitudes of −23.2 < M I < −18.8 mag and bulge magnitudes of −22.9 < M I < −16.1 mag. Detailed bulge-disk-bar decompositions with GALFIT show that 93% of the galaxies have extended disks, 39% have bars, and 5% have no bulges at all at the limits of our observations. Based on the Sérsic index and bulge-to-total ratio, we conclude that the majority of the galaxies with disks are likely to contain pseudobulges and very few of these low-mass BHs live in classical bulges. The fundamental plane of our sample is offset from classical bulges and ellipticals in a way that is consistent with the scaling relations of pseudobulges. The sample has smaller velocity dispersion at fixed luminosity in the Faber-Jackson plane compared with classical bulges and elliptical galaxies. The galaxies without disks are structurally more similar to spheroidals than to classical bulges according to their positions in the fundamental plane, especially the Faber-Jackson projection. Overall, we suggest that BHs with mass 10 6 M live in galaxies that have evolved secularly over the majority of their history. A classical bulge is not a prerequisite to host a BH.

We use global three dimensional radiation magneto-hydrodynamic simulations to study the properties of inner regions of accretion disks around a 5 × 10 8 M BH black hole with mass accretion rates reaching 7% and 20% of the Eddington value. This region of the disk is supported by magnetic pressure with surface density significantly smaller than the values predicted by the standard thin disk model but with a much larger disk scale height. The disks do not show any sign of thermal instability over many thermal time scales. More than half of the accretion is driven by radiation viscosity in the optically thin corona region for the lower accretion rate case, while accretion in the optically thick part of the disk is driven by the Maxwell and Reynolds stresses from MRI turbulence. Coronae with gas temperatures 10 8 K are generated only in the inner ≈ 10 gravitational radii in both simulations, being more compact in the higher accretion rate case. In contrast to the thin disk model, surface density increases with increasing mass accretion rate, which causes less dissipation in the optically thin region and a relatively weaker corona. The simulation results may explain the formation of X-ray coronae in Active Galactic Nuclei (AGNs), the compact size of such coronae, and the observed trend of optical to X-ray luminosity with Eddington ratio for many AGNs.

Luminous blue variables are massive, evolved stars that exhibit large variations in luminosity and size on timescales from months to years, with high associated rates of mass loss. In addition to this on-going variability, these stars exhibit outburst phases, during which their size increases and as a result their effective temperature decreases, typically to about 9,000 kelvin. Outbursts are believed to be caused by the radiation force on the cooler, more opaque, outer layers of the star balancing or even exceeding the force of gravity, although the exact mechanisms are unknown and cannot be determined using one-dimensional, spherically symmetric models of stars because such models cannot determine the physical processes that occur in this regime. Here we report three-dimensional simulations of massive, radiation-dominated stars, which show that helium opacity has an important role in triggering outbursts and setting the observed effective temperature during outbursts of about 9,000 kelvin. It probably also triggers the episodic mass loss at rates of 10 to 10 solar masses per year. The peak in helium opacity is evident in our three-dimensional simulations only because the density and temperature of the stellar envelope (the outer part of the star near the photosphere) need to be determined self-consistently with convection, which cannot be done in one-dimensional models that assume spherical symmetry. The simulations reproduce observations of long-timescale variability, and predict that convection causes irregular oscillations in the radii of the stars and variations in brightness of 10-30 per cent on a typical timescale of a few days. The amplitudes of these short-timescale variations are predicted to be even larger for cooler stars (in the outburst phase). This short-timescale variability should be observable with high-cadence observations.

Both radiative and mechanical feedback from Active Galactic Nuclei have been found to be important for the evolution of elliptical galaxies. We compute how a shock may be driven from a central black hole into the gaseous envelope of an elliptical galaxy by such feedback (in the form of nuclear winds) using high resolution 1-D hydrodynamical simulations. We calculate the synchrotron emission from the electron cosmic rays accelerated by the shocks (not the jets) in the central part of elliptical galaxies, and we also study the synchrotron spectrum's evolution using the standard diffusive shock acceleration mechanism, which is routinely applied to supernova remnants. We find quantitative consistency between the synchrotron radio emission produced via this mechanism with extant observations of elliptical galaxies which are undergoing outbursts. Additionally, we also find that synchrotron optical and X-ray emission can co-exist inside elliptical galaxies during a specific evolutionary phase subsequent to central outbursts. In fact, our calculations predict a peak synchrotron luminosity of ∼ 1.3 × 10 6 L ⊙ at the frequency 5 GHz (radio band), of ∼ 1.1 × 10 6 L ⊙ at 4.3 × 10 14 Hz (corresponding to the absolute magnitude -10.4 in R band), and of ∼ 1.5 × 10 7 L ⊙ at 2.4 × 10 17 Hz (soft X-ray, 0.5 -2.0 keV band).

OBJECTIVES To report a retrospective series of 130 Chinese patients with penoscrotal extramammary Paget’s diseases (EMPD), with a long‐term follow‐up, and thus improve the diagnosis and therapy of this disease. PATIENTS AND METHODS The history, clinical presentation, pathology, treatment, and prognosis of 130 patients were analysed. All cases were confirmed by skin biopsy, and then the patients had local wide resection to remove the involved skin and subcutaneous tissue. The large defective wound was reconstructed using a split‐thickness skin graft or local flap. RESULTS Forty‐five patients were evaluated by frozen‐section biopsy of the margins during surgery, five of whom had positive margins and then had an extended resection immediately. Most of these patients had local skin or adjacent scrotal flaps to cover their skin defects. Of the 130 patients, 81 had a mean (range) follow‐up of 3.2 (0.5–10) years after surgery. Five of nine patients with positive margins and three (4%) of 72 with negative margins had tumour recurrence. Five patients died from metastatic disease. CONCLUSIONS Penoscrotal EMPD needs be differentiated from other chronic dermatitis. A 3 cm surgical margin should be sufficient and frozen‐section pathological examinations are necessary for some complicated conditions. Skin grafts or local flaps are good for large skin defects.

The presence of neutron stars in at least three ultraluminous X-ray sources is now firmly established and offers an unambiguous view of super-critical accretion. All three systems show long-timescale periods (60-80 days) in the X-rays and/or optical, two of which are known to be super-orbital in nature. Should the flow be classically super critical, i.e. the Eddington limit is reached locally in the disc (implying surface dipole fields that are submagnetar in strength), then the large scale-height flow can precess through the Lense-Thirring effect which could provide an explanation for the observed super-orbital periods. By connecting the details of the Lense-Thirring effect with the observed pulsar spin period, we are able to infer the moment-of-inertia and therefore equation-of-state of the neutron star without relying on the inclination of, or distance to the system. We apply our technique to the case of NGC 7793 P13 and demonstrate that stronger magnetic fields imply stiffer equations of state. We discuss the caveats and uncertainties, many of which can be addressed through forthcoming radiative magnetohydrodynamic (RMHD) simulations and their connection to observation.