Monthly Notices is one of the three largest general primary astronomical research publications. It is an international journal, published by the Royal Astronomical Society. This article 1 describes its publication policy and practice.

Monthly Notices of the Royal Astronomical Society

Gravitational Field of a Spinning Mass as an Example of Algebraically Special Metrics

EDDINGTON'S “Internal Constitution of the Stars” was published in 1926 and gives what now ranks as a classical account of his own researches and of the general state of the theory at that time. Since then, a tremendous amount of work has appeared. Much of it has to do with the construction of stellar models with different equations of state applying in different zones. Other parts deal with the effects of varying chemical composition, with pulsation and tidal and rotational distortion of stars, and with the precise relations between the interior and the atmosphere of a star. The striking feature of all this work is that so much can be done without assuming any particular mechanism of stellar energy-generation. Only such very comprehensive assumptions are made about the distribution and behaviour of the energy sources that we may expect future knowledge of their mechanism to lead mainly to more detailed results within the framework of the existing general theory. An Introduction to the Study of Stellar Structure By S. Chandrasekhar. (Astrophysical Monographs sponsored by The Astrophysical Journal.) Pp. ix+509. (Chicago: University of Chicago Press; London: Cambridge University Press, 1939.) 50s. net.

An Introduction to the Study of Stellar Structure

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.

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Advection-Dominated Accretion: Underfed Black Holes and Neutron Stars

Clusters of galaxies, as the largest virialized systems in the Universe, are ideal laboratories to study the formation and evolution of cosmic structures. The luminous matter of clusters consists of galaxies and of an embedding intracluster medium (ICM), which has been heated to temperatures of tens of millions degrees, and thus is detected through its thermal emission in the soft X-ray regime. Most of the detailed knowledge of galaxy clusters has been obtained in recent years from the study of ICM through X-ray Astronomy. At the same time, radio observations have proved that the ICM is mixed with non-thermal components, i.e. highly relativistic particles and large-scale magnetic fields, detected through their synchrotron emission. The knowledge of the properties of these non-thermal ICM components has increased significantly, owing to sensitive radio images and to the development of theoretical models. Diffuse synchrotron radio emission in the central and peripheral cluster regions has been found in many clusters. Moreover large-scale magnetic fields appear to be present in all galaxy clusters, as derived from Rotation Measure (RM) studies. Non-thermal components are linked to the cluster X-ray properties, and to the cluster evolutionary stage, and are crucial for a comprehensive physical description of the intracluster medium. They play an important role in the cluster formation and evolution. We review here the observational properties of diffuse non-thermal sources detected in galaxy clusters: halos, relics and mini-halos. We discuss their classification and properties. We report published results up to date and obtain and discuss statistical properties. We present the properties of large-scale magnetic fields in clusters and in even larger structures: filaments connecting galaxy clusters. We summarize the current models of the origin of these cluster components, and outline the improvements that are expected in this area from future developments thanks to the new generation of radio telescopes.

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Clusters of galaxies: observational properties of the diffuse radio emission

The nature and origin of turbulence and magnetic fields in the intergalactic space are important problems that are yet to be understood. We propose a scenario in which turbulent-flow motions are induced via the cascade of the vorticity generated at cosmological shocks during the formation of the large-scale structure. The turbulence in turn amplifies weak seed magnetic fields of any origin. Supercomputer simulations show that the turbulence is subsonic inside clusters and groups of galaxies, whereas it is transonic or mildly supersonic in filaments. Based on a turbulence dynamo model, we then estimated that the average magnetic field strength would be a few microgauss (μG) inside clusters and groups, approximately 0.1 μG around clusters and groups, and approximately 10 nanogauss in filaments. Our model presents a physical mechanism that transfers the gravitational energy to the turbulence and magnetic field energies in the large-scale structure of the universe.

https://science.sciencemag.org/content/sci/320/5878/909.full.pdf

Turbulence and magnetic fields in the large-scale structure of the universe.

Site-dependent luminescence of Cu+ ions in silica glass

If ultraYhigh-energy cosmic rays (UHECRs) originate from extragalactic sources, understanding the propagation of charged particles through the magnetized large-scale structure (LSS) of the universe is crucial in the search for the astrophysical accelerators. Based on a novel model of the turbulence dynamo, we estimate the intergalactic magnetic fields (IGMFs) in cosmological simulations of the formation of the LSS. Under the premise that the sources of UHECRs are strongly associated with the LSS, we consider a model in which protons with E � 10 19 eVare injected by sources that represent active galactic nuclei, located inside clusters of galaxies. With the model IGMFs, we then follow the trajectories of the protons, taking into account the energy losses due to interactions with the cosmic background radiation. For observers located inside groups of galaxies like ours, about 70% and 35% of UHECR events above 60 EeVarrive within � 15 � and � 5 � , respectively, of the source position with time delays of less than � 10 7 yr. This implies that the arrival direction of super-GZK protons might exhibit a correlation with the distribution of cosmologicalsourcesonthesky.Inthismodel,nearbysources(within10Y20Mpc)shouldcontributesignificantlytothe particle flux above � 10 20 eV. Subject headingg cosmic rays — large-scale structure of universe — magnetic fields — methods: numerical

/pdf/propagation-of-ultra-high-energy-protons-through-the-3es62l0e3j.pdf

Propagation of Ultra-High-Energy Protons through the Magnetized Cosmic Web

Accretion flows having low angular momentum and low viscosity can have standing shock waves. These shocks arise because of the presence of multiple sonic points in the flow. We study the region of the parameter space in which multiple sonic points occur in viscous flows in the absence of cooling. We also separate the parameter space into regions allowing steady shocks and oscillating shocks. We quantify the nature of two critical viscosities which separate the flow topologies. The post-shock region being hotter, it emits harder X-rays and oscillating shocks cause oscillating X-ray intensities giving rise to quasi-periodic oscillations. We show that with the increase in viscosity parameter, the shock always moves closer to the black hole. This implies an enhancement of the quasi-periodic oscillation frequency as viscosity is increased.

Properties of accretion shock waves in viscous flows around black holes

If ultra-high-energy cosmic rays (UHECRs) originate from extragalactic sources, understanding the propagation of charged particles through the magnetized large scale structure (LSS) of the universe is crucial in the search for the astrophysical accelerators. Based on a novel model of the turbulence dynamo, we estimate the intergalactic magnetic fields (IGMFs) in cosmological simulations of the formation of the LSS. Under the premise that the sources of UHECRs are strongly associated with the LSS, we consider a model in which protons with E >10^{19} eV are injected by sources that represent active galactic nuclei located inside clusters of galaxies. With the model IGMFs, we then follow the trajectories of the protons, while taking into account the energy losses due to interactions with the cosmic background radiation. For observers located inside groups of galaxies like ours, about 70% and 35% of UHECR events above 60 EeV arrive within ~15 degree and ~5 degree, respectively, of the source position with time delays of less than ~10^7 yr. This implies that the arrival direction of super-GZK protons might exhibit a correlation with the distribution of cosmological sources on the sky. In this model, nearby sources (within 10 - 20 Mpc) should contribute significantly to the particle flux above ~10^{20} eV.

/pdf/propagation-of-uhe-protons-through-magnetized-cosmic-web-55qhq9jd7l.pdf

Santabrata Das

Papers

Turbulence and magnetic fields in the large-scale structure of the universe.

Site-dependent luminescence of Cu+ ions in silica glass

Propagation of Ultra-High-Energy Protons through the Magnetized Cosmic Web

Properties of accretion shock waves in viscous flows around black holes

Propagation of UHE Protons through Magnetized Cosmic Web