X-ray emission from the Ultramassive Black Hole candidate NGC1277: implications and speculation on its origin

We study the X-ray emission from NGC1277, a galaxy in the core of the Perseus cluster, for which van den Bosch et al. have recently claimed the presence of an UltraMassive Black Hole (UMBH) of mass 1.7 times 10^10 Msun, unless the IMF of the stars in the stellar bulge is extremely bottom heavy. The X-rays originate in a power-law component of luminosity 1.3 times 10^40 erg/s embedded in a 1 keV thermal minicorona which has a half-light radius of about 360 pc, typical of many early-type galaxies in rich clusters of galaxies. If Bondi accretion operated onto the UMBH from the minicorona with a radiative efficiency of 10 per cent, then the object would appear as a quasar with luminosity 10^46 erg/s, a factor of almost 10^6 times higher than observed. The accretion flow must be highly radiatively inefficient, similar to past results on M87 and NGC3115. The UMBH in NGC1277 is definitely not undergoing any significant growth at the present epoch. We note that there are 3 UMBH candidates in the Perseus cluster and that the inferred present mean mass density in UMBH could be 10^5 Msun/Mpc^3, which is 20 to 30 per cent of the estimated mean mass density of all black holes. We speculate on the implied growth of UMBH and their hosts, and discuss the possibiity that extreme AGN feedback could make all UMBH host galaxies have low stellar masses at redshifts around 3. Only those which end up at the centres of groups and clusters later accrete large stellar envelopes and become Brightest Cluster Galaxies. NGC1277 and the other Perseus core UMBH, NGC1270, have not however been able to gather more stars or gas owing to their rapid orbital motion in the cluster core.Comment: 5 pages, 4 figures, MNRAS in pres

Double-layer shocks in a magnetized quantum plasma

The formation of small but finite amplitude electrostatic shocks in the propagation of quantum ion-acoustic waves (QIAWs) obliquely to an external magnetic field is reported in a quantum electron-positron-ion (e-p-i) plasma. Such shocks are seen to have double-layer (DL) structures composed of the compressive and accompanying rarefactive slow-wave fronts. Existence of such DL shocks depends critically on the quantum coupling parameter $H$ associated with the Bohm potential and the positron to electron density ratio $\delta$. The profiles may, however, steepen initially and reach a steady state with a number of solitary waves in front of the shocks. Such novel DL shocks could be a good candidate for particle acceleration in intense laser-solid density plasma interaction experiments as well as in compact astrophysical objects, e.g., magnetized white dwarfs.Comment: 4 pages, 1 figure (to appear in Physical Review E

Interagency Science and Research: Final Project Report

The major accomplishment of this project was the development of the SNAP Science and Research Strategy: an 11-chapter document designed to integrate and coordinate scientific research programs in Southern Nevada and improve the efficiency and effectiveness of these programs. The Strategy is intended to inform and guide SNAP agencies in identifying and articulating highest priority science and research needs, sharing resources and funds from other sources, and eliminating redundancy between research programs within their focus areas. The major focus areas of the Strategy are Fire, Invasive Species, Watersheds and Landscapes, Biodiversity, Cultural Resources, Historic Content, Recreation, Land Use, and Education. The Strategy was approved by the SNAP Board in March 2009

Lymphocyte reactivity in patients with carcinoma of the breast and large bowel.

The reactivity of lymphocytes from patients with either carcinoma of the breast or large bowel has been studied using the human to mouse normal lymphocyte transfer (NLT) reaction. It was found that, in the case of breast cancer, there was a direct correlation between the clinical stage and a reduced NLT reaction. Only patients with regional lymph node or generalized metastases showed significantly reduced lymphocyte reactivity. However, in the case of large bowel cancer there was a generalized reduction in NLT reactivity which was independent of the clinical stage. Incubation of lymphocytes from individuals without neoplastic disease in serum or plasma from breast cancer patients, showing reduced NLT reactivity, resulted in a reduced NLT reaction. This appears to be indicative of the presence of circulating "blocking factor" in such patients

The Spectral Signature of Dust Scattering and Polarization in the Near IR to Far UV. I. Optical Depth and Geometry Effects

Spectropolarimetry from the near IR to the far UV of light scattered by dust provides a valuable diagnostic of the dust composition, grain size distribution and spatial distribution. To facilitate the use of this diagnostic, we present detailed calculations of the intensity and polarization spectral signature of light scattered by optically thin and optically thick dust in various geometries. The polarized light radiative transfer calculations are carried out using the adding-doubling method for a plane-parallel slab, and are extended to an optically thick sphere by integrating over its surface. The calculations are for the Mathis, Rumple & Nordsieck Galactic dust model, and cover the range from 1 $\mu m$ to 500 \AA. We find that the wavelength dependence of the scattered light intensity provides a sensitive probe of the optical depth of the scattering medium, while the polarization wavelength dependence provides a probe of the grain scattering properties, which is practically independent of optical depth. We provide a detailed set of predictions, including polarization maps, which can be used to probe the properties of dust through imaging spectropolarimetry in the near IR to far UV of various Galactic and extragalactic objects. In a following paper we use the codes developed here to provide predictions for the dependence of the intensity and polarization on grain size distribution and composition.Comment: 29 pages + 21 figures, accepted for the Astrophysical Journal Supplement February 2000 issue. Some revision, mostly in the introduction and the conclusions, and a couple of correction

Revealing Nuclear Pions Using Electron Scattering

A model for the pionic components of nuclear wave functions is obtained from light front dynamical calculations of binding energies and densities. The pionic effects are small enough to be consistent with measured nuclear di-muon production data and with the nucleon sea. But the pion effects are large enough to predict substantial nuclear enhancement of the cross section for longitudinally polarized virtual photons for the kinematics accessible at Jefferson Laboratory.Comment: 9 pages, 4 figure

Large Scale Cavities Surrounding Microquasars Inferred from Evolution of their Relativistic Jets

The black hole X-ray transient XTE J1550-564 has undergone a strong outburst in 1998 and two relativistic X-ray jets have been detected years later with the $\it Chandra$ X-ray observatory; the eastern jet was found previously to have decelerated after its first detection. Here we report a full analysis of the evolution of the western jet; significant deceleration is also detected in the western side. Our analysis indicates that there is a cavity outside the central source and the jets first traveled with constant velocity and then were slowed down by the interactions between the jets and the interstellar medium (ISM). The best fitted radius of the cavity is $\sim$0.31 pc on the eastern side and $\sim$0.44 pc on the western side, and the densities also show asymmetry, of $\sim$0.034 cm$^{-3}$ on the east to $\sim$0.12 cm$^{-3}$ on the west. The best fitted magnetic fields on both sides are $\sim$0.5 mG. Similar analysis is also applied to another microquasar system, H 1743-322, and a large scale low density region is also found. Based on these results and the comparison with other microquasar systems, we suggest a generic scenario for microquasar jets, classifying the observed jets into three main categories, with different jet morphologies (and sizes) corresponding to different scales of vacuous environments surrounding them. We also suggest that either continuous jets or accretion disk winds, or both may be responsible for creating these cavities. Therefore X-ray jets from microquasars provide us with a promising method of probing the environment of accreting black holes.Comment: 29 pages, 5 tables, 7 figures. Accepted for publication in Ap

Infinite Nuclear Matter on the Light Front: Nucleon-Nucleon Correlations

A relativistic light front formulation of nuclear dynamics is developed and applied to treating infinite nuclear matter in a method which includes the correlations of pairs of nucleons: this is light front Brueckner theory. We start with a hadronic meson-baryon Lagrangian that is consistent with chiral symmetry. This is used to obtain a light front version of a one-boson-exchange nucleon-nucleon potential (OBEP). The accuracy of our description of the nucleon-nucleon (NN) data is good, and similar to that of other relativistic OBEP models. We derive, within the light front formalism, the Hartree-Fock and Brueckner Hartree-Fock equations. Applying our light front OBEP, the nuclear matter saturation properties are reasonably well reproduced. We obtain a value of the compressibility, 180 MeV, that is smaller than that of alternative relativistic approaches to nuclear matter in which the compressibility usually comes out too large. Because the derivation starts from a meson-baryon Lagrangian, we are able to show that replacing the meson degrees of freedom by a NN interaction is a consistent approximation, and the formalism allows one to calculate corrections to this approximation in a well-organized manner. The simplicity of the vacuum in our light front approach is an important feature in allowing the derivations to proceed. The mesonic Fock space components of the nuclear wave function are obtained also, and aspects of the meson and nucleon plus-momentum distribution functions are computed. We find that there are about 0.05 excess pions per nucleon.Comment: 39 pages, RevTex, two figure

Assessing medical students' attitudes towards learning communication skills – which components of attitudes do we measure?

BACKGROUND: The Communication Skills Attitudes Scale (CSAS) created by Rees, Sheard and Davies and published in 2002 has been a widely used instrument for measuring medical students' attitudes towards learning communication skills. Earlier studies have shown that the CSAS mainly tests two dimensions of attitudes towards communication; positive attitudes (PAS) and negative attitudes (NAS). The objectives of our study are to explore the attitudes of Norwegian medical students towards learning communication skills, and to compare our findings with reports from other countries. METHODS: The CSAS questionnaire was mailed simultaneously to all students (n = 3055) of the four medical schools in Norway in the spring of 2003. Response from 1833 students (60.0%) were analysed by use of SPSS ver.12. RESULTS: A Principal component analysis yielded findings that differ in many respects from those of earlier papers. We found the CSAS to measure three factors. The first factor describes students' feelings about the way communication skills are taught, whereas the second factor describes more fundamental attitudes and values connected to the importance of having communication skills for doctors. The third factor explores whether students feel that good communication skills may help them respecting patients and colleagues. CONCLUSION: Our findings indicate that in this sample the CSAS measures broader aspects of attitudes towards learning communication skills than the formerly described two-factor model with PAS and NAS. This may turn out to be helpful for monitoring the effect of different teaching strategies on students' attitudes during medical school

Astrophysical evidence for the existence of black holes

Following a short account of the history of the idea of black holes, we present a review of the current status of the search for observational evidence of their existence aimed at an audience of relativists rather than astronomers or astrophysicists. We focus on two different regimes: that of stellar-mass black holes and that of black holes with the masses of galactic nuclei.Comment: 23 pages, 3 figures, TeX forma