We describe new optically thin solutions for rotating accretion flows around black holes and neutron stars. These solutions are advection dominated, so that most of the viscously dissipated energy is advected radially with the flow. We model the accreting gas as a two temperature plasma and include cooling by bremsstrahlung, synchrotron, and Comptonization. We obtain electron temperatures $T_e\sim 10^{8.5}-10^{10}$K. The new solutions are present only for mass accretion rates $\dot M$ less than a critical rate $\dot M_{crit}$ which we calculate as a function of radius $R$ and viscosity parameter $\alpha$. For $\dot M<\dot M_{crit}$ we show that there are three equilibrium branches of solutions. One of the branches corresponds to a cool optically thick flow which is the well-known thin disk solution of Shakura \& Sunyaev (1973). Another branch corresponds to a hot optically thin flow, discovered originally by Shapiro, Lightman \& Eardley (1976, SLE). This solution is thermally unstable. The third branch corresponds to our new advection-dominated solution. This solution is hotter and more optically thin than the SLE solution, but is viscously and thermally stable. It is related to the ion torus model of Rees et al. (1982) and may potentially explain the hard X-ray and $\gamma$-ray emission from X-ray binaries and active galactic nuclei.

/pdf/advection-dominated-accretion-underfed-black-holes-and-cc41v8tdhl.pdf

Advection-Dominated Accretion: Underfed Black Holes and Neutron Stars

This review discusses the current status of supermassive black hole research, as seen from a purely observational standpoint Since the early ‘90s, rapid technological advances, most notably the launch of the Hubble Space Telescope, the commissioning of the VLBA and improvements in near-infrared speckle imaging techniques, have not only given us incontrovertible proof of the existence of supermassive black holes, but have unveiled fundamental connections between the mass of the central singularity and the global properties of the host galaxy It is thanks to these observations that we are now, for the first time, in a position to understand the origin, evolution and cosmic relevance of these fascinating objects

Supermassive Black Holes in Galactic Nuclei: Past, Present and Future Research

The accurate measurement of extragalactic distances is a central challenge of modern astronomy, being required for any realistic description of the age, geometry and fate of the Universe. The measurement of relative extragalactic distances has become fairly routine, but estimates of absolute distances are rare1. In the vicinity of the Sun, direct geometric techniques for obtaining absolute distances, such as orbital parallax, are feasible, but such techniques have hitherto been difficult to apply to other galaxies. As a result, uncertainties in the expansion rate and age of the Universe are dominated by uncertainties in the absolute calibration of the extragalactic distance ladder2. Here we report a geometric distance to the galaxy NGC4258, which we infer from the direct measurement of orbital motions in a disk of gas surrounding the nucleus of this galaxy. The distance so determined—7.2 ± 0.3 Mpc—is the most precise absolute extragalactic distance yet measured, and is likely to play an important role in future distance-scale calibrations.

A geometric distance to the galaxy NGC4258 from orbital motions in a nuclear gas disk

Although there exists a relationship between alcohol consumption and alcoholic liver disease at both the aggregate and individual levels, it is also well established that less than one-third of alcoholics or heavy drinkers develop serious alcohol-related liver damage. A number of factors have been proposed to account for this susceptibility. Evidence supporting the direct dose-response relationship and the role of genetic and environmental factors in influencing vulnerability are reviewed. To date, no consistent evidence attests to the significance of any one factor in the susceptibility to developing alcoholic liver disease.

/pdf/epidemiology-of-alcoholic-liver-disease-3cqpqkwrst.pdf

Epidemiology of alcoholic liver disease.

https://www.amjmed.com/article/0002-9343(89)90297-0/pdf

Ethanol reduces bone formation and may cause osteoporosis

We present an H2O maser emission study of the Seyfert galaxy IC 2560 based on single-dish and VLBI observations. The maser emission was detected in multiple velocity ranges: one around the systemic velocity, one blue-shifted from the systemic velocity by ∼ 220–420 km s −1 , and one red-shifted by ∼ 210–350 km s −1 . This was the first detection of high-velocity features in this galaxy. The velocity of the systemic features drifts at a mean rate of 2.62 ±0.09 km s −1 yr −1 . Assuming a compact Keplerian disk at the nucleus, the inner and outer radii of this disk are 0.07 and 0.26 pc, respectively. The central mass confined within the disk inner radius is 2.8 ×10 6 M� , and

/pdf/water-vapor-maser-emission-from-the-seyfert-2-galaxy-ic-2560-46zduqy46v.pdf

Water-Vapor Maser Emission from the Seyfert 2 Galaxy IC 2560: Evidence for a Super-Massive Black Hole

Alcoholic liver disease: Pathobiology, epidemiology, and clinical aspects

Search for Extremely-High- Velocity H_2O Maser Emission in Seyfert Galaxies

The Australia Telescope Compact Array (ATCA) is likely to be the first operational mm-wave interferometer in the Southern Hemisphere This paper examines some possible atmospheric phase correction strategies for the array, notes the applicability of these to future large mm-wave arrays, and points to the usefulness of the ATCA in assessing the various approaches

Phase Correction Strategies for the Australia Telescope Compact Array at Short Wavelengths

We made a survey of water-vapor maser emission for 93 AGNs with the Nobeyama 45-m and Mopra 22-m telescopes from 1999 to 2002. A megamaser was detected in a Seyfert 2 galaxy, NGC 6926, at a distance of 80Mpc, in 2002 June. [Greenhill et al. (2003a) have also reported a detection of the megamaser at the close date.] The peak flux density was 110mJy, and the total isotropic luminosity was 340 L� . The maser shows triply peaked spectrum, suggesting an edge-on disk. A narrow-line feature of the maser components at VLSR = 6001kms −1 was strongly variable with a time scale of a few tens of days, and the variation should be of intrinsic origin. We also showed a possibility of variability of water-vapor maser emission of a megamaser previously detected in a Seyfert/ultraluminous FIR galaxy, NGC 6240.

Water-Vapor Maser Survey for Active Galactic Nuclei : A Megamaser in NGC 6926

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