We study proton-rich nucleosynthesis in windlike outflows from {gamma}-ray bursts accretion disks with the aim of determining if such outflows are a site of the nup process. The efficacy of this nup process depends on thermodynamic and hydrodynamic factors. We discuss the importance of the entropy of the material, the ...

We present self-similar solutions for advection-dominated accretion flows with radial viscous force in the presence of outflows from the accretion flow or infall. The axisymmetric flow is treated in variables integrated over polar sections and the effects of infall and outflows on the accretion ...

The observational consequences of the merger scenario for massive star formation are explored and contrasted with the gradual accumulation of mass by accretion. In high-density protostar clusters, envelopes and disks provide a viscous medium that can dissipate the kinetic energy of passing stars, greatly enhancing the probability of capture. Protostellar mergers may produce ...

We aim to monitor T Tauri star disk emission features and jet outflow morphologies to determine how these features vary with disk accretion rate, and how and when the outflow responds to major accretion events. Young stars are surrounded by circumstellar disks through which they accrete mass. ...

OUTFLOWS FROM DYNAMO-ACTIVE PROTOSTELLAR ACCRETION DISCS BRIGITTA VON REKOWSKI1 , AXEL BRANDENBURG2, Newcastle, UK Abstract. An axisymmetric model of a cool, dynamo-active accretion disc is applied by the disc dynamo driven by the magneto-rotational instability and some form of outflow is indeed seen

The formation and evolution of a circumstellar disk in magnetized cloud cores are investigated from a prestellar core stage until ~104 yr after protostar formation. In the circumstellar disk, fragmentation first occurs due to gravitational instability in a magnetically inactive region, and substellar-mass objects appear. The substellar-mass objects lose their orbital angular momenta by ...

Context. Plasma accreting onto classical T Tauri stars (CTTS) is believed to impact the stellar surface at free-fall velocities, generating a shock. Current time-dependent models describing accretion shocks in CTTSs are one-dimensional, assuming that the plasma moves and transports energy only along magnetic field lines (? ? 1). Aims: We investigate the ...

... storms developed along a boundary which was ... environment as no boundaries were observed in ... impacted a previous outflow induced stable layer). ...

It is well known that there is mass outflow in cataclysmic variables, since IUE observations show P Cyg profiles of various high-excitation lines of C IV and S IV. It is proposed here that these outflows are hydromagnetic winds from accretion disks. The winds extract angular momentum from these systems and therefore drive secular ...

We present a physical model for the coevolution of massive spheroidal galaxies and active nuclei at their centers. Supernova heating is increasingly effective in slowing down the star formation and in driving gas outflows in smaller and smaller dark matter halos. Thus the more massive protogalaxies virializing at early times are the sites of faster star formation. The ...

The birth of stars involves not only accretion but also, counter-intuitively, the expulsion of matter in the form of highly supersonic outflows. Although this phenomenon has been seen in young stars, a fundamental question is whether it also occurs among newborn brown dwarfs: these are the so-called 'failed stars', with masses between stars and planets, ...

A white dwarf (WD) approaching the Chandrasekhar mass may in several cases undergo accretion-induced collapse (AIC) to a neutron star (NS) before a thermonuclear explosion ensues. It has generally been assumed that AIC does not produce a detectable supernova (SN). If, however, the progenitor WD is rapidly rotating (as may be expected due to its prior ...

We consider the specific case of disc accretion for negligibly low viscosity and infinitely high electric conductivity. The key component in this model is the outflowing magnetized wind from the accretion disc, since this wind effectively carries away angular momentum of the accreting matter. Assuming magnetic ...

We model the expected X-ray polarization induced by complex reprocessing in the active nucleus of the Seyfert 2 galaxy NGC 1068. Recent analysis of infrared interferometry observations suggests that the ionized outflows ejected by the central engine are not aligned with the symmetry axis of the obscuring torus. This conclusion was obtained by extrapolating ...

We model the expected X-ray polarization induced by complex reprocessing in the active nucleus of the Seyfert 2 galaxy NGC 1068. Recent analysis of infrared interferometry observations suggests that the ionized outflows ejected by the central engine are not aligned with the symmetry axis of the obscuring torus. This conclusion was obtained by extrapolating ...

Apr 22, 2011 ... He is constraining the physics of black hole accretion, outflows and ... multiwavelength observations (including X-rays and gamma-rays) in ...

We find a self-consistent solution for the outflow rate from an accretion disc around a black hole. The centrifugal pressure dominated shock in a transonic accretion flow can act as a Compton cloud by emitting radiation in the form of hard X-rays. It is also the base of an outflow where considerable matter is ...

In this paper we extend our previous works on spherically symmetric accretion onto black holes and superspinars to the case in which the fluid has a finite angular momentum initially. We run 2.5D and 3D general relativistic hydrodynamic simulations of the accretion of a fat disk. We study how the accretion process changes by changing ...

... Understanding of accretion disks, accretion flows, X-ray induced winds, compact obect evolution are all in a primitive state. ...

We describe the first three-dimensional simulation of the gravitational collapse of a massive, rotating molecular cloud that includes heating by both non-ionizing and ionizing radiation. These models were performed with the FLASH code, incorporating a hybrid, long characteristic, ray-tracing technique. We find that as the first protostars gain sufficient mass to ionize the ...

We describe the first three-dimensional simulation of the gravitational collapse of a massive, rotating molecular cloud that includes heating by both non-ionizing and ionizing radiation. These models were performed with the FLASH code, incorporating a hybrid, long characteristic, ray-tracing technique. We find that as the first protostars gain sufficient mass to ionize the ...

We examine the nucleosynthesis products that are produced in the outflow from rapidly accreting disks. We find that the type of element synthesis varies dramatically with the degree of neutrino trapping in the disk and therefore the accretion rate of the disk. Disks with relatively high accretion rates such as ...

We examine the nucleosynthesis products that are produced in the outflow from rapidly accreting disks. We find that the type of element synthesis varies dramatically with the degree of neutrino trapping in the disk and therefore the accretion rate of the disk. Disks with relatively high accretion rates such as {dot ...

We study the accretion of modified Chaplygin gas upon different types of black holes. Modified Chaplygin gas is one of the best candidates for a combined model of dark matter and dark energy. In addition, from a field theoretical point of view the modified Chaplygin gas model is equivalent to that of a scalar field having a self-interacting potential. We formulate the ...

A general treatment of disk star formation is developed from a dissipative multiphase model, with the dominant dissipation due to cloud collisions. The Schmidt-Kennicutt (SK) law emerges naturally for star-forming disks and starbursts. We predict that there should be an inverse correlation between Tully-Fisher law and SK law residuals. The model is extended to include a multiphase treatment of ...

Dynamo�generated Turbulence and Outflows from Accretion Discs B y Axel Brandenburg Department scale magnetic fields. Comparison with mean�field dynamo theory is made. This theory is then used, in the case of the sun there is turbulent convection which leads to dynamo action. However, the strong shear

young stars in the Taurus and Orion dark clouds with the echelle spectrograph on the 4�m telescope in the flow. The appropriate equation for stars at the distance of the Taurus dark is log 10 Mw = \\Gamma4ACCRETION AND OUTFLOW FROM YOUNG STARS Patrick Hartigan Department of Space Physics and Astronomy

The collapse of massive molecular clumps can produce high mass stars, but the evolution is not simply a scaled-up version of low mass star formation. Outflows and radiative effects strongly hinder the formation of massive stars via accretion. A necessary condition for accretion growth of a hydrostatic object up to high masses M > ...

In this paper we continue our study on the accretion process onto superspinning Kerr objects with no event horizon (super-spinars). We discuss the counterpart of the Bondi accretion onto black holes. We first report the results of our numerical simulations. We found a quasi-steady-state configuration for any choice of the parameters of our model. The most ...

The first VLBI images of H2O maser emission in the Circinus Galaxy AGN show both an accretion disk and outflow 0.1 to 1 pc from the central engine. The maser traces a warped, edge-on accretion disk between radii of about 0.1 and 0.4 pc that is bound by a 1.3�106 Msolar central mass. The rotation curve is somewhat flatter than a ...

Models of accretion discs and their associated outflows often incorporate assumptions of axisymmetry and symmetry across the disc plane. However, for turbulent discs these symmetries only apply to averaged quantities and do not apply locally. The local asymmetries can induce local imbalances in outflow power across ...

Molecular line surveys and fully sampled spectral line maps at 1.3 and 0.87 mm are used to examine the physical and chemical characteristics of the extreme Class I sources IRAS 4A and 4B in the L1450/NGC 1333 molecular cloud complex. A very well collimated, jetlike molecular outflow emanates from IRAS 4A, with a dynamical age of a few thousand years. Symmetric, clumpy ...

Classical T Tauri stars offer a unique window into star+disk systems that are still in the accretion/outflow phase yet are no longer surrounded by an opaque circumstellar envelope. These objects hold the key to understanding how magnetospheric accretion occurs, how accretion powers outflows, and what the physical ...

We investigate the launching and stability of extragalactic jets through magnetohydrodynamic simulations of jet evolution. In these simulations, a small scale equilibrium magnetic corona is twisted by a differentially rotating accretion disk. Two-dimensional calculations show the formation of a collimated outflow. This outflow is ...

We present the spectral analysis of three Suzaku XIS observations of 3C 111 requested to monitor the predicted variability of its ultra-fast outflow on ~7 days time-scales. We detect an ionized iron emission line in the first observation and a blue-shifted absorption line in the second, when the flux is ~30% higher. The location of the material is constrained at <0.006pc ...

We present a study of molecular outflows toward a sample of 69 luminous IRAS point sources. The sample is associated with dense molecular gas and has far-infrared luminosities ranging from 102 to 105 Lsolar, indicating these objects as regions likely forming high-mass stars. Mapping in the CO J=2-1 line shows that molecular outflows are ubiquitous in these ...

A unique case of radiation-induced heart disease associated with acquired right ventricular outflow obstruction is presented. Surgical management of this case is described.

We use a suite of cosmological hydrodynamic simulations to systematically quantify the accretion rates of baryons into dark matter haloes and the resulting baryon mass fractions, as a function of halo mass, redshift and baryon type (including cold and hot gas). We find that the net baryonic accretion rates through the virial radius are sensitive to ...

Recent months have witnessed dramatic progress in our understanding of short ?-ray burst (SGRB) sources. There is now general agreement that SGRBs�or at least a substantial subset of them�are capable of producing directed outflows of relativistic matter with a kinetic luminosity exceeding by many millions that of active galactic nuclei. Given the twin requirements of ...

Collimated relativistic outflows-also known as jets-are amongst the most energetic phenomena in the Universe. They are associated with supermassive black holes in distant active galactic nuclei, accreting stellar-mass black holes and neutron stars in binary systems and are believed to be responsible for gamma-ray bursts. The physics of these jets, however, ...

To study the outflows from accretion disks, we solve the set of hydrodynamic equations for accretion disks in spherical coordinates (r?phi) to obtain the explicit structure along the ?-direction. Using self-similar assumptions in the radial direction, we change the equations to a set of ordinary differential equations about the ...

We review the results from multi-dimensional, time-dependent simulations of gas dynamics in AGN. We will focus on two types of outflows powered by radiation emitted from the AGN central engine: (i) outflows driven from the innermost part of an accretion disk and (2) outflows driven from a large-scale inflow that is ...

We present two-dimensional hydrodynamical simulations of slowly rotating gas that is under the influence of the gravity of a super massive black hole and is irradiated by a thin UV accretion disc and a spherical X-ray corona. We calculate the accretion luminosity of a system based on the accretion rate which is assumed to be equal to ...

A survey for molecular outflows was carried out by mapping the CO J=2-1 line toward a sample of 69 luminous IRAS point sources. Sixty objects have IRAS luminosities from 103 to 105 Lsolar and are associated with dense gas traced by NH3, identifying them as high-mass star-forming regions. Among 69 sources, 65 sources have data that are suitable for outflow ...

Recent months have witnessed dramatic progress in our understanding of SGRBs. There is now general agreement that SGRBs can produce directed outflows of relativistic matter with a kinetic luminosity exceeding by many millions that of AGN. The requirements of energy and compactness indicate that SGRB activity can be ascribed to a modest fraction of a solar mass of gas ...

We consider hot accretion disk outflows from black hole-neutron star mergers in the context of the nucleosynthesis they produce. We begin with a three-dimensional numerical model of a black hole-neutron star merger and calculate the neutrino and antineutrino fluxes emitted from the resulting accretion disk. We then follow the element ...

The origin of cosmic magnetic (B) fields remains an open question. It is generally believed that very weak primordial B fields are amplified by dynamo processes, but it appears unlikely that the amplification proceeds fast enough to account for the fields presently observed in galaxies and galaxy clusters. In an alternative scenario, cosmic B fields are generated near the inner edges of ...

The origin of cosmic magnetic (B) fields remains an open question. It is generally believed that very weak primordial B fields are amplified by dynamo processes, but it appears unlikely that the amplification proceeds fast enough to account for the fields presently observed in galaxies and galaxy clusters. In an alternative scenario, cosmic B fields are generated near the inner edges of ...

We propose that the magnetic fields in the accretion disks of active galactic nuclei (AGNs) are generated by azimuthal electric currents due to the difference between the plasma electron and ion velocities that arises when the electrons are retarded by interactions with the AGN photons (the Poynting - Robertson battery). This process provides a unique relation between the ...

The origin of cosmicmagnetic (B) fields remains an open question. It is generally believed that very weak primordial B fields are amplified by dynamo processes, but it appears unlikely that the amplification proceeds fast enough to account for the fields presently observed in galaxies and galaxy clusters. In an alternative scenario, cosmic B fields are generated near the inner edges of ...

Extensive observations of the molecular gas in the young, compact planetary nebula M1-16 have been made, using the Swedish-ESO-Submillimeter Telescope. A map of the CO J = 2-1 emission shows that the molecular envelope contains both a slow and a fast outflow with expansion velocities of 19 km/s and greater than 34 km/s, respectively. The slow outflow is ...

A violent outflow of high-velocity gas is one of the first manifestations of the formation of a new star. Such outflows emerge bipolarly from the young object and involve amounts of energy similar to those involved in accretion processes. The youngest (proto-)stellar low-mass objects known to date (the Class 0 protostars) present a ...

FU Orionis (FUOR) outbursts are major optical brightening episodes in low-mass protostars that evidently correspond to rapid mass accretion events in the innermost region of a protostellar disc. The outbursts are accompanied by strong outflows, with the inferred mass outflow rates reaching �10 per cent of the mass inflow rates. Shu ...

FU Orionis (FUOR) outbursts are major optical brightening episodes in low-mass protostars that evidently correspond to rapid mass accretion events in the innermost region of a protostellar disc. The outbursts are accompanied by strong outflows, with the inferred mass outflow rates reaching �10 per cent of the mass inflow rates. Shu ...

The mechanism by which outflows and plausible jets are driven from black hole systems still remains observationally elusive. This notwithstanding, several observational evidences and deeper theoretical insights reveal that accretion and outflow/jet are strongly correlated. We model an advective disk-outflow coupled ...

In the standard scenario for galaxy evolution young star-forming galaxies transform into red bulge-dominated spheroids, where star formation has been quenched. To explain this transformation, a strong negative feedback generated by accretion onto a central super-massive black hole is often invoked. The depletion of gas resulting from quasar-driven outflows ...

We explore thermal X-ray iron line emission from the galactic X-ray binary GX 339-4 in the off state, using the models of the advection-dominated accretion flow (ADAF) without or with outflows. The equivalent widths of hydrogen-like and helium-like thermal iron lines are calculated with different model parameters including viscosity parameter ?, mass ...

Classical T Tauri stars undergo magnetospheric accretion, power outflows, and possess the physical and chemical conditions in their disks to give rise to planet formation. Existing high resolution FUV spectra verify that this spectral region offers unique diagnostics of these processes, which have the potential to significantly advance our understanding of ...

(blueshifted) Fe-K absorption lines from highly ionized Fe in some QSOs. (Pounds , Reeves et al. 2003..). " PG 1211+143: v~ 24000 km/s ...

Figure 2: Sclectcd channel lna~)s of infall and outftour, }vith the vdocities indicated itl each. [mtlcl. (a) ~'hc st ructurc of Cls 0(2-1 ) elnissioll as a function of ...

In contrast with bipolar jets from the magnetic rotating bodies with accretion flows, it is expected for pulsar winds that high energy outflow is in a ring-like shape. It is also suggested that the kinetic energy flux is comparable with the Poynting flux.

Rapidly-accreting black holes and young, rapidly-rotating magnetars ('proto-magnetars') are two possible central engines for gamma-ray bursts (GRBs). The midplane of neutrino-cooled accretion disks and the surface of proto-magnetars are both neutron-rich, with a neutron-to-proton ratio n|p>>1. If a large neutron fraction is ...

Lu Ye, TP-02. A Possible Energy Mechanism for Cosmological Gamma-ray Bursts ... Hyper-Eddington Accretion and Collimated Outflow from Black Holes ...

Steady state models of magnetized accretion disks that power centrifugally driven outflows are presented. Self-similar solutions for Keplerian disks that are dominated by ambipolar diffusion are constructed and the analogous solutions for resistive disks are presented. In each case, it is shown that one can obtain steady state field configurations that ...

We combine an analytic model for anisotropic outflows and galaxy formation with numerical simulations of large-scale structure and halo formation to study the impact of galactic outflows on the evolution of the intergalactic medium (IGM). Using this algorithm, we have simulated the evolution of a comoving volume of size (15 Mpc)3 in the ?CDM universe. ...

We examine theoretically the behaviour of the inner accretion disk in GRS 1915+105 when soft X-ray dips are present in the X-ray light curve. We assume the presence of a radial shock in the accretion disk, as in some of the Two Component Advective Flow (TCAF) solutions. We discuss the behaviour of the flux tubes inside a TCAF (which we name Magnetized TCAF ...

Massive stars produce so much light that the spherically averaged radiation pressure exerted on the gas and dust around them is stronger than their gravitational attraction, a condition that has long been expected to prevent them from growing by accretion. We present three-dimensional adiation-hydrodynamic simulations of the collapse of a massive prestellar core which include ...

Nucleosynthesis could take place in the hot regions of accretion and outflow around a black hole. We here investigate possible composition changes due to nuclear reaction processes in an accretion disk by calculating a set of self-similar solutions of an advection-dominated accretion flow. We find that 26Al, 51Cr, ...

In this Letter we investigate the properties of advection-dominated accretion flows (ADAFs) fed by the evaporation of a Shakura-Sunyaev accretion disk (SSD). In our picture, the ADAF fills the central cavity evacuated by the SSD and extends beyond the transition radius into a coronal region. We find that, because of global angular momentum conservation, a ...

Formation of massive stars is an area of active research. Like low mass stars, high mass stars go through a phase of accretion and outflow. High mass outflows are distinct from low mass outflows in that the former are poorly collimated and spread out into a butterfly pattern. The Orion outflow ...

It has been clear for many years now that the process of accretion on to a compact object is largely dominated by magnetic fields. The magnetic field channels the accretion flow onto strongly magnetized stars such as magnetic white dwarfs (cataclysmic variables), and neutron stars (accreting X-ray pulsars). Magnetic fields are likely ...

We consider the spin angular momentum evolution of the accreting components of Algol-type binary stars. In wider Algols the accretion is through a disc so that the accreted material can transfer enough angular momentum to the gainer that material at its equator should be spinning at breakup. We demonstrate that even a small amount of ...

We develop an exploratory model for the outer, gravitationally unstable regions of accretion disks around massive black holes. We consider black holes of mass 10(6) to 10(10) Msun, and primeval or solar abundances. In a first step we study star formation and evolution in a purely gaseous marginally unstable disk, and we show that unstable fragments should collapse rapidly and ...

We investigate the vertical structure of neutrino-dominated accretion flows in spherical coordinates. In our calculation, the empty funnel along the rotation axis can naturally explain the neutrino annihilable ejection. The outflow is possible due to the positive Bernoulli function, and the luminosity of neutrino annihilation is enhanced by one or two ...

The supercritical wind theory of Papers II and III is applied to winds driven by accretion phenomena. An expression for the total luminosity LT is derived in terms of the accretion rate dotMT and injection radius r?. When applied specifically to accretion disks, the theory becomes the supercritical counterpart to standard subcritical ...

Accretion disks are invoked to explain a host of astrophysical phenomena, from protostellar objects to AGN. And yet the mechanism allowing accretion disks to operate are completely unknown. This proposal seeks to observe the ``smoking gun'' signature of magnetically-driven viscosity in accretion disks. ...

We propose that the disruption of subpermafrost aquifers on Mars by the thermal- or pressure-induced

It is shown that some aspects of the accretion disc physics can be experimentally simulated with the use of an array of properly directed plasma jets created by intense laser beams. For the laser energy of 1 to 3 kJ, one can create a quasi-planar disc with the Reynolds number exceeding 104 and magnetic Reynolds number in the range of 10-100. The way of seeding the disc with ...

Radiative winds and jets from luminous accretion disks/tori are reviewed. Among various models of astrophysical jets, plasma outflows emanating from accretion disks/tori and accelerated by the radiation pressure is the most promising one. Here explained are the roles of radiation pressure force and radiation drag force. Rise and fall ...

CCD photometry reveals a hot spot on the surface of the hot accretion gainer in this supergiant O type binary with a big accretion rate. This spot is as bright as 25000 Suns. The orbital period of this system is 33.108 days. The absorption-line spectrum contains multiple lines of He I, Si III and N II. The star is associated with H II region formed by ...

Local hydromagnetic simulations of accretion-disc turbulence currently provide the most convincing evidence that the origin of turbulence in discs could be the Balbus-Hawley magnetorotational instability. The main results of such calculations are highlighted with particular emphasis on the generation of large-scale magnetic fields. Comparison with mean-field dynamo theory is ...

Accretion Disks around Stars and the Process of Planet Formation National Radio Astronomy. This process is regulated by ejecting gas in "jet-like" outflows. II. Planets form later from the remnants of the disk. Planets may only form when conditions around the star are "just right." III. Planets have been

e present a new near-infrared imaging survey of 50 luminous young stellar outflow candidates. Using high spatial resolution observations in the v=1-0 S(1) line of H_2 we detect the outflows with a high success rate: 76% of the objects exhibit H_2 emission and 50% or more of the objects exhibit aligned H_2 emission features suggesting collimated ...

Young stars can produce X-rays by different mechanisms: Coronal activity, accretion shocks and shocks in outflows. We propose to observe two targets within one field-of-view (FOV): SU Aur is accreting mass from a disk and shows violent coronal activity. We will study the time evolution of stellar flares on time scales from seconds to ...

Outflowing jets are observed in a variety of astronomical objects such as accreting compact objects from X-ray binaries (XRBs) to active galactic nuclei (AGN), as well as at stellar birth and death. Yet we still do not know exactly what they are comprised of, why and how they form, or their exact relationship with the accretion ...

The accretion-induced collapse (AIC) of a white dwarf to form a neutron star can leave behind a rotationally supported disc with mass of up to ~ 0.1 Msolar. The disc is initially composed of free nucleons but as it accretes and spreads to larger radii, the free nucleons recombine to form helium, releasing sufficient energy to unbind the remaining disc. ...

The accretion-induced collapse (AIC) of a white dwarf to form a neutron star can leave behind a rotationally supported disk with mass of up to ~ 0.1 M_sun. The disk is initially composed of free nucleons but as it accretes and spreads to larger radii, the free nucleons recombine to form helium, releasing sufficient energy to unbind the remaining disk. Most ...

We present the results of three-dimensional general relativistic hydrodynamic simulations of adiabatic and spherically symmetric accretion in Kerr space-time. We consider compact objects with spin parameter |a{sub *}|{<=}1 (black holes) and with |a{sub *}|>1 (superspinars). Our full three-dimensional simulations confirm the formation of equatorial ...

We present the results of three-dimensional general relativistic hydrodynamic simulations of adiabatic and spherically symmetric accretion in Kerr space-time. We consider compact objects with spin parameter |a*|?1 (black holes) and with |a*|>1 (superspinars). Our full three-dimensional simulations confirm the formation of equatorial outflows for high ...

Observational evidence suggests long-duration, collapsar-type gamma-ray bursts (GRBs) may have been more common in the early universe. These events are thought to be powered by accretion disks around black holes (AD-BHs). While GRBs require AD-BHs, not all AD-BHs will power bursts and therefore their formation will be more common than GRBs themselves. ...

The properties of external accretion disks (disks with a central source of angular momentum) are explored both analytically and numerically. An illustrative example of the effect of a disk of material around a binary star on the stellar separation is considered. A Greens-function-type solution is considered in which an initial ring of matter is put in orbit around the central ...

We discuss transportation and redistribution of energy and angular momentum in the magnetic connection (MC) process and Blandford-Payne (BP) process. MC results in readjusting the interior viscous torque, and its effects are operative not only in but also beyond the MC region. The BP process is invoked to transfer the �excessive� angular momentum from an accretion disc. In ...

We outline recent progress in understanding the accretion of plasma to rotating magnetized stars obtained from global axisymmetric (2D) and 3D magnetohydrodynamic (MHD) simulations in three main areas: (1.) Formation of jets from disk accretion onto rotating magnetized stars: From simulations where the viscosity and magnetic diffusivity within the disk are ...

Magnetohydrodynamic models of collimated outflows produced by accretion discs around compact objects can be used for interpreting the phenomenology of active astrophysical objects as young stellar objects, microquasars, X-ray binaries, gamma-ray bursts, extended radio galaxies and active galactic nuclei. In the present work, we discuss how the strength of ...

The broad-line region (BLR) disappears in many low-luminosity active galactic nuclei (AGNs), the reason of which is still controversial. The BLRs in AGNs are believed to be associated with the outflows from the accretion disks. Most of the low-luminosity AGNs contain advection-dominated accretion flows (ADAFs) which are very hot and ...

Detailed synoptic and dynamic analyses of outflow from tornado-producing thunderstorms of 23 April 1968 were made by using conventional rawinsonde data combined with ATS III pictures. It was found that the pre-existing flow at the cirrus level over storm areas changed dramatically into outflow as the storms developed. When the storms reached their mature ...

Models of accretion disks around a star in a binary system predict that the disk will have a retrograde precession with a period a factor of ~10 times the orbital period. If the star+disk system ejects a bipolar outflow, this outflow will be subject to the effects of both the orbital motion and the precession. We present an analytic, ...

Models of accretion disks around a star in a binary system predict that the disk will have a retrograde precession with a period a factor of approx10 times the orbital period. If the star+disk system ejects a bipolar outflow, this outflow will be subject to the effects of both the orbital motion and the precession. We present an ...

Context. Extreme-ultraviolet (EUV) and X-ray photons from classical T Tauri stars are powerful ionization and heating agents that drive disk chemistry, disk instabilities, and photoevaporative flows. The mid-infrared fine-structure line of [Ne ii] at 12.81 ?m has been proposed to trace gas in disk surface layers heated and ionized by stellar X-ray and EUV radiation. Aims: We aim at locating the ...

Coronal Mass Ejection Induces Ionosphere Mass Ejection. Plasma outflows Using NASA's Polar spacecraft, researchers have found the first direct evidence that ...

A solid theoretical understanding of how inflowing, accreting plasma around black holes and other compact objects gives rise to outflowing winds and jets is still lacking, despite decades of observations. The fact that similar processes and morphologies are observed in both X-ray binaries and active galactic nuclei has led to suggestions that the ...

We show that a moderately massive disk (10/sup -5/--10/sup -2/ M/sub sun/) can cause the Lense-Thirring precession of the compact object (neutron star or black hole) at its center. The inner regions of the disk (r< or approx. =10/sup 8/ cm) align with the equator of an will precess at the same rate as the compact object. We propose that this disk-driven precession produces the 164 day period in ...

Various papers on accretion disks (ADs) and magnetic fields in astrophysics are presented. Individual topics addressed include: relevance of magnetic fields to stars and ADs, nonlinear breakup of the sun's toroidal field, accretion and particle acceleration by spiral shock wages, MHD flows in ADs and jets, slender flux tubes in ADs, magnetic fields in the ...

Black holes from stellar to galactic scales are observed to accrete material from their environments and, via an as yet unknown mechanism, produce jets of outflowing plasma. In X-ray binaries (XRBs), the systems display radically different radiative properties depending on the amount of captured gas reaching the event horizon. These modes of behavior ...

We present time-dependent models of the remnant accretion discs created during compact object mergers, focusing on the energy available from accretion at late times and the composition of the disc and its outflows. We calculate the dynamics near the outer edge of the disc, which contains the majority of the disc's mass and determines ...

A promising new diagnostic for identifying actively accreting massive young stellar objects (MYSOs) has emerged from large-scale Spitzer surveys of the Galactic plane: extended emission in the IRAC 4.5 micron band, believed to trace shocked molecular gas in active protostellar outflows. I will discuss the GLIMPSE catalog of extended 4.5 micron sources ...

A general mechanism is presented for generating pressure-driven winds that are intrinsically bipolar from objects undergoing disk accretion. The energy librated in a boundary layer shock as the disk matter impacts the central object is shown to be sufficient to eject a fraction ..beta..approx.10/sup -2/ to 10/sup -3/ of the accreted mass. These winds are ...

We present the detailed global structure of black hole accretion flows and outflows through newly performed two-dimensional radiation-magnetohydrodynamic simulations. By starting from a torus threaded with weak toroidal magnetic fields and by controlling the central density of the initial torus, ?0, we can reproduce three distinct modes of ...

As a direct consequence of the luminosity generated through accretion, quasars can eject energetic outflows at high velocities. These outflows are directly observed in Broad Absorption Line (BAL) quasars through their deep, blue-shifted absorption lines. To date, one of the main challenges in constraining the fundamental properties ...

We present for the first time axisymmetric magnetohydrodynamic simulations which show the formation of intrinsically asymmetric or one-sided outflows or jets from disc accretion on to a rotating star with a complex magnetic field. The intrinsic magnetic field of the star is assumed to consist of a superposition of an aligned dipole and an aligned ...

Symbiotic stars, which are interacting binary stars usually composed by a late type giant and a very hot/luminous white dwarf, are a powerful laboratory to investigate mass loss phenomenon relevant to a wide range of astrophysical topics: aspherical mass loss, collimated winds from accretion disks, colliding winds, mass loss induced by violent ...

A long infrared jet has been discovered by the Spitzer c2d Legacy Program in core A of L1251. It is associated with a very embedded Class 0 object with an accretion luminosity of about 0.9 L sun derived by radiative transfer model fitting to the observed spectral energy distribution. Comparing the observed Infrared Array Camera colors along the infrared jet with those ...

A long infrared jet has been discovered by the Spitzer c2d Legacy Program in core A of L1251. It is associated with a very embedded Class 0 object with an accretion luminosity of about 0.9 L {sub sun} derived by radiative transfer model fitting to the observed spectral energy distribution. Comparing the observed Infrared Array Camera colors along the infrared jet with those ...

Narrow-line Seyfert 1 (NLS1) galaxies are believed to harbor low-mass black holes accreting at high rates, and they are therefore important targets when studying the nature of black hole growth, galaxy evolution, and accretion physics. We have rigorously studied the physical properties of a sample of NLS1 galaxies. We briefly review previous findings and ...

Recently it has become apparent that proto-stellar-like outflow activity extends to the brown dwarf (BD) mass regime. While the presence of accretion appears to be the common ingredient in all objects known to drive jets fundamental questions remain unanswered. The more prominent being the exact mechanism by which jets are launched, and whether this ...

Actualistic subduction-accretion models developed from studies of subduction initiation, volcanic arc splitting, and arc-trench rollback processes in the western and southwestern Pacific suggest that refractory magmas such as boninite, high-magnesium andesite, and adakite may be key petrologic signals of `hot' subduction initiation. In the western Pacific, two types of model ...

In star formation, magnetic fields act as a cosmic angular momentum extractor that increases mass accretion rates onto protostars and, in the process, creates spectacular outflows. However, recently it has been argued that this magnetic brake is so strong that early protostellar disks-the cradles of planet formation-cannot form. Our three-dimensional ...

Narayan and Yi (1994, AAA 064.083) found that the Bernoulli parameter is a positive constant in advection-dominated accretion flows, thereby mass outflow being inevitable. We find, however, that their conclusion depends critically on their assumptions required to derive their self-similar solutions (i.e., substantial infall velocity, comparable to the ...

An extended XMM-Newton observation of the Seyfert 1 galaxy NGC 4051 has revealed a rich absorption line spectrum indicating the presence of a photoionized outflow with a wide range of velocities and ionization parameter. At low continuum fluxes an emission line spectrum is well defined with both narrow and broad emission components of several abundant metal ions. The ...

Solid recovery impact-induced volatile loss experiments on the Murchison C2M meteorite indicate that

Solid recovery impact-induced volatile loss experiments on the Murchison C2M meteorite indicate that

Over the last number of years, spectroscopic studies have strongly supported the assertion that protostellar accretion and outflow activity persist to the lowest masses. Indeed, previous to this work, the existence of three brown dwarf (BD) outflows had been confirmed by us. In this paper, we present the results of our latest ...

We study the rate at which gas accretes on to galaxies and haloes and investigate whether the accreted gas was shocked to high temperatures before reaching a galaxy. For this purpose, we use a suite of large cosmological, hydrodynamical simulations from the OverWhelmingly Large Simulations project, which uses a modified version of the smoothed particle ...

Hydromagnetic disk winds have great potential as a general theory for the production and collimation of astrophysical jets in both protostellar and black hole environments. We first review the analytic stationary theory of these outflows as well as recent numerical simulations of MHD disk winds. We then focus on simulations that we have done on winds from magnetized disks ...

Gamma-ray bursts, while rare, may be important contributors to galactic nucleosynthesis. Here we consider the types of nucleosynthesis that can occur as material is ejected from a gamma-ray burst accretion disk. We calculate the composition of material within the disk as it dissociates into protons and neutrons and then use a parameterized outflow model to ...

Aims: We seek to understand the way massive stars form. The case of a luminous YSO IRAS 17527-2439 is studied in the infrared. Methods: Imaging observations of IRAS 17527-2439 are obtained in the near-IR JHK photometric bands and in a narrow-band filter centred at the wavelength of the H2 1-0S(1) line. The continuum-subtracted H2 image is used to identify outflows. The data ...

Bipolar outflows are a common aspect of the accretion process that leads to the formation of low-mass stars like the Sun. During the most active accretion stages, jets are observed in the optical forbidden lines of abundant ions of oxygen, sulfur, etc.. These lines indicate that the jets have temperatures in the range from 5,000-10,000 ...

A continuous monitoring of the neutron star spin period in Her X-1 and its X-ray luminosity performed with Swift/BAT over the last five years revealed unexpected behavior of the pulsar that appears to switch between two different regimes of the angular momentum exchange between the neutron star and accretion disc. A smooth spin-up of the neutron star is occasionally ...

We present radiation hydrodynamics simulations of the collapse of massive pre-stellar cores. We treat frequency dependent radiative feedback from stellar evolution and accretion luminosity at a numerical resolution down to 1.27 AU. In the 2D approximation of axially symmetric simulations, it is possible for the first time to simulate the whole accretion ...

We propose a simplified model of outflow/jet driven by the Blandford-Payne (BP) process from advection-dominated accretion flows (ADAF) and derive the expressions of the BP power and disk luminosity based on the conservation laws of mass, angular momentum and energy. We fit the 2-10 keV luminosity and kinetic power of 15 active galactic nucleus (AGNs) of ...

It is now widely accepted that most galaxies undergo an active phase, during which a central super-massive black hole generates vast radiant luminosities through the gravitational accretion of gas. Winds launched from a rotating accretion disk surrounding the black hole are thought to play a critical role, allowing the disk to shed angular momentum that ...

There is a significant non-linear correlation between the Eddington ratio (Lbol/LEdd) and the Eddington-scaled kinetic power (Lkin/LEdd) of jets in low luminosity active galactic nuclei (AGNs). It is believed that these low luminosity AGNs contain advection-dominated accretion flows (ADAFs). We adopt the ADAF model developed by Li & Cao, in which the global dynamics of ...

We investigate the Green's function energy/space distribution of the relativistic particles accelerated in viscous, advection-dominated accretion disks containing standing, centrifugally-supported shock waves. The dynamical structure of the accreting gas is described using a new model for viscous, shocked disks recently reported by the authors, and a ...

Fermi-LAT has recently detected two gamma-ray bubbles disposed symmetrically with respect to the Galactic plane. The bubbles have been suggested to be in a quasi-steady state, inflated by ongoing star formation over the age of the Galaxy. Here we propose an alternative picture where the bubbles are the remnants of a large-scale wide-angle outflow from Sgr A*, the supermassive ...

{\\it Fermi}-LAT has recently detected two gamma ray bubbles disposed symmetrically with respect to the Galactic plane. The bubbles have been suggested to be in a quasi-steady state, inflated by ongoing star formation over the age of the Galaxy. Here we propose an alternative picture where the bubbles are the remnants of a large-scale wide-angle outflow from \\sgra, the SMBH ...

Using resistive magnetohydrodynamics simulation, we consider circumstellar disk formation in a strongly magnetized cloud. As the initial state, an isolated cloud core embedded in a low-density interstellar medium with a uniform magnetic field was adopted. The cloud evolution was calculated until almost all gas inside the initial cloud fell onto either the circumstellar disk or a protostar, and a ...

The observations show that less massive the galaxies are, the higher on average is their specific star formation rates (SSFR = SFR/Ms, Ms is the stellar mass). Such a trend, called the 'SSFR downsizing' (SSFR-DS) phenomenon, is seen for local and high-z (back to z~1-2) galaxy samples. We use observational data related only to disc galaxies and explore the average SSFR change with z for different ...

Deep observations with the Very Large Array of A0620-00, performed in 2005 August, resulted in the first detection of radio emission from a black hole binary at X-ray luminosities as low as 10-8.5 times the Eddington limit. The measured radio flux density, of 51 +/- 7 ?Jy at 8.5 GHz, is the lowest reported for an X-ray binary system so far, and is interpreted in terms of partially self-absorbed ...

The cosmic star formation rate is observed to drop sharply after redshift z= 2. We use two large, cosmological, smoothed particle hydrodynamics simulations to investigate how this decline is related to the evolution of gas accretion and to outflows driven by active galactic nuclei (AGN). We find that the drop in the star formation rate follows a ...

The cosmic star formation rate is observed to drop sharply after redshift z=2. We use a large, cosmological, smoothed particle hydrodynamics simulation to investigate how this decline is related to the evolution of gas accretion and to outflows driven by active galactic nuclei (AGN). We find that the drop in the star formation rate follows a corresponding ...

Active Galactic Nuclei are believed to be powered by accretion onto a Super-Massive Black Hole. In order to have material falling into the SMBH, angular momentum conservation requires a counterpart for this accretion that is fueling the SMBH in the AGN. Outflows might play an essential role in active galactic nuclei. They show common ...

We have obtained infrared colors and limiting magnitudes from 1.25-4.8 micrometers for a sample of 26 of the cm continuum radio sources located in the core of the rho Oph molecular cloud. Their colors demonstrate that the majority of the sources appear to be heavily reddened objects surrounded by circumstellar accretion disks. In these cases the radio emission most likely ...

The basic characteristics of line-driven winds from UV accretion disks were investigated analytically and numerically. Stellar winds have been compared with the outflow from a disk surrounding a supermassive black hole. It is found that in the approximation of vertically streaming radiation close to the disk photosphere, the existence of steady disk winds ...

The authors have investigated both analytically and numerically the basic characteristics of line-driven winds from UV accretion disks. Stellar winds have been compared with the outflow from a disk surrounding a supermassive black hole. The authors find that in the approximation of vertically streaming radiation close to the disk photosphere, the existence ...

The literature is full of a large number of accretion flow models, each of which claims to be the correct one. We present here the most general possible flow configuration around a black hole, different regions of which have characteristics of different models such as the Bondi flow, the Keplerian disk, the transonic flows, the thick disks, the disks with ...

Classical T Tauri stars are pre-main-sequence objects that undergo simultaneous accretion, wind outflow, and coronal X-ray emission. The impact of plasma on the stellar surface from magnetospheric accretion streams is likely to be a dominant source of energy and momentum in the upper atmospheres of these stars. This paper presents a ...

We use cosmological smoothed particle hydrodynamic simulations to study the kinematic signatures of cool gas accretion onto a pair of well-resolved galaxy halos. We find that cold-flow streams and gas-rich mergers produce a circumgalactic component of cool gas that generally orbits with high angular momentum about the galaxy halo before falling in to build the disk. This ...

Aims: Cold steady-state disk wind theory from near Keplerian accretion disks requires a large scale magnetic field at near equipartition strength. However the minimum magnetization has never been tested with time dependent simulations. We investigate the time evolution of a Shakura-Sunyaev accretion disk threaded by a weak vertical magnetic field. The ...

I present new insights about accretion and ejection physics in low-mass X-ray binaries based on high-resolution Chandra HETGS studies of accretion disk winds in the microquasar GRS 1915+105. First, using 10 years of Chandra observations to probe the long-term connection between accretion disk winds and relativistic jets, I show how ...

We consider axisymmetric viscous accretion flows where a fraction of of the viscously dissipated energy is stored in the accreting gas as entropy and a fraction 1 - f is radiated. Assuming alpha-viscosity we obtain a two-parameter family of self-similar solutions. Very few such exact self-consistent solutions are known for viscous differentially rotating ...

About half of the binary systems are close enough to each other for mass to be exchanged between them at some point in their evolution, yet the accretion mechanism in wind accreting binaries is not well understood. We study the dynamical effects of gravitational focusing by a binary companion on winds from late-type stars. In particular, we investigate the ...

We have used the Long Baseline Array to observe the Circinus Galaxy H2O megamasers on two epochs separated by 49 d. The masers were observed to be highly variable, consistent with previous studies. We observe rapid variations in the linewidth and central velocity of the maser's spectral profile. The characteristics of these spectral variations suggest that the masers have an anisotropic structure, ...

Context: The spectacular outflow of HH 46/47 is driven by HH 46 IRS 1, an embedded Class I Young Stellar Object (YSO). Although much is known about this region from extensive optical and infrared observations, the properties of its protostellar envelope and molecular outflow are poorly constrained. Aims: Our aim is to characterize the size, mass, density ...

We used the Owens Valley Millimeter Array and the Very Large Array to obtain interferometric maps at millimeter and centimeter wavelengths in both the continuum and various lines [HCO+ (1-0), H13CO+ (1-0), SiO (v=0, J=2-1) and H13CN (1-0)] toward a sample of 11 high-mass protostellar candidates. These sources are known from a previous study to be associated with dense gas and dust and to not be ...

The supercritical disk accretion flow with radiatively driven outflows is studied based on two-dimensional radiation-hydrodynamic simulations for a wide range of the mass input rate, M?input, which is the mass supplied from the outer region to the disk per unit time. The ?-prescription is adopted for the viscosity. We employ ?=0.5, as well as ?=0.1, for ...

One of the most important unresolved issues for galaxy formation theory is to understand the origin of exponential galactic disks. We use a disk galaxy evolution model to investigate whether galaxies with exponential surface brightness profiles can be produced in a cosmologically motivated framework for disk galaxy formation. Our model follows the detailed accretion, cooling, ...

Using high resolution, fully cosmological smoothed particle hydrodynamical simulations of dwarf galaxies in a Lambda cold dark matter Universe, we show how high redshift gas outflows can modify the baryon angular momentum distribution and allow pure disc galaxies to form. We outline how galactic outflows preferentially remove low angular momentum material ...

While feedback from the central supermassive black hole likely affects the host galaxy evolution in the distant universe, we can not directly observe these processes at work. We can, however, easily observe the host galaxy and AGN properties of nearby sources. Previous surveys of outflows in local AGN relied on biased samples of the UV/soft X-ray brightest sources, making ...

We measure and analyze the energy, momentum, and mass feedback efficiencies due to radiation from active galactic nuclei (AGNs) in relatively large-scale outflows (from ~0.01 to ~10 pc). Our measurements are based on the two-dimensional (axisymmetric) and time-dependent radiation-hydrodynamical simulations recently presented in Kurosawa & Proga. In that paper, we studied ...

Aims: We investigate the influence of turbulent viscosity on the collapse of a rotating molecular cloud core with axial symmetry, in particular, on the first and second collapse phase, as well as the evolution of the second (protostellar) core during its first accretion period. By using extensive numerical calculations, we monitor the intricate interactions between the newly ...

We report the completion of a large optical spectroscopic survey of radio-loud AGNs which had the goal of finding more objects with double-peaked Balmer lines. We have identified a small but distinct subclass of radio-loud AGNs whose Balmer line profiles are double-peaked and can be fitted with a model of emission from a relativistic circular disk. These objects stand out not just because of their ...

We explore explosions of massive stars, which are triggered via the quark-hadron phase transition during the early post-bounce phase of core-collapse supernovae. We construct a quark equation of state, based on the bag model for strange quark matter. The transition between the hadronic and the quark phases is constructed applying Gibbs conditions. The resulting quark-hadron hybrid equations of ...

Models have shown that quasars are a crucial ingredient in the evolution of massive galaxies. Outflows play a key role in the story of quasars and their host galaxies, by helping regulate the accretion process, the star-formation rate and mass of the host galaxy (i.e., feedback). The prescription for modeling outflows as a contributor ...

As part of an extensive study of the physical properties of active galactic nuclei (AGNs) we report high spatial resolution near-IR integral-field spectroscopy of the narrow-line region (NLR) and coronal-line region (CLR) of seven Seyfert galaxies. These measurements elucidate for the first time the two-dimensional spatial distribution and kinematics of the recombination line Br? and ...

Mass outflows driven by stars and active galactic nuclei (AGNs) are a key element in many current models of galaxy evolution. They may produce the observed black-hole-galaxy mass relation and regulate and quench both star formation in the host galaxy and black hole accretion. However, observational evidence of such feedback processes through ...

The fine structure of the region of formation of a protostar in the dense molecular cloud OMC-1 of the Orion Nebula was studied during a period of enhanced activity in 1998-1999, with an angular resolution of 50 �as and a velocity resolution of ? v = 0.053 km/s. Inclusions of ice granules in the bipolar outflow were detected and identified. The velocity of the ...

We show how accretion rate governs the physical properties of broad-line, narrow-line, and lineless active galactic nuclei (AGNs). We avoid the systematic errors plaguing previous studies of AGN accretion rate by using accurate accretion luminosities from well-sampled multiwavelength SEDs from the Cosmic Evolution Survey (COSMOS), and ...

We perform axisymmetric relativistic magnetohydrodynamic simulations to investigate the acceleration and collimation of jets and outflows from disks around compact objects. Newtonian gravity is added to the relativistic treatment in order to establish the physical boundary condition of an underlying accretion disk in centrifugal and pressure equilibrium. ...

A promising new diagnostic for identifying actively accreting massive young stellar objects (MYSOs) has emerged from large-scale Spitzer Space Telescope surveys of the Galactic plane: extended emission in the IRAC 4.5 micron band, believed to trace shocked molecular gas in active protostellar outflows. I present the GLIMPSE I catalog of extended 4.5 micron ...

The formation of low mass stars takes place with the assistance of an accretion disk that transports gas and dust from the envelope of the system to the star, and a jet that removes angular momentum and allows accretion to proceed. In the radio, these ionized jets can be studied very close to the star via the thermal (free-free) emission they produce and ...

The black holes in the hearts of bright elliptical galaxies are commonly observed to be associated with powerful relativistic jets. The mechanism by which material entering the accretion radius is converted into jet power remains the subject of much debate. At the same time, the interplay between the relativistic jet and the interstellar/intergalactic medium is the topic of ...

Ultraviolet resonance lines appear to be powerful tools for diagnostics and study of the outflows from cataclysmic variable stars. The origin of these winds and their geometry are not known at present. In order to compare observed lines from the IUE database with synthetic line profiles from accretion disk winds, we have developed a numerical radiation ...

Interferometric observations of the inner accretion flow around Sgr A* as well as spectroscopic observations of relativistically broadened iron lines from AGN carry the potential of mapping the spacetimes of astrophysical black holes. This potential will be realized only if the radiation from the inner accretion flow can be identified and distinguished ...

We calculate the emission from relativistic flows in black hole systems using a fully general relativistic radiative transfer formulation, with flow structures obtained by general relativistic magneto-hydrodynamic simulations. We consider thermal free-free emission and thermal synchrotron emission. Bright filament-like features protrude (visually) from the accretion disk ...

Using wetlands as sink of nutrients, phosphorus in particular, is becoming an increasingly attractive alternative to conventional wastewater treatment technology. In this paper, we briefly review the mechanism of phosphorus retention in wetlands, as well as previous modeling efforts. ABayesian method is then proposed for estimating the long-term phosphorus accretion rate in ...

Accretion onto a black hole can produce enormous power which has a profound influence on its surroundings. The power is emitted in the form of radiation or as a matter outflow such as a jet. Observational evidence of the accretion flow in the immediate vicinity of the black hole where the power is released, and of its effects on both ...

Aims: We examine an Infrared Dark Cloud (IRDC) at high spatial resolution as a means to study rotation, outflow, and infall at the onset of massive star formation. Methods: The IRDC 18223-3 was observed at 1.1 mm and 1.3 mm with the Submillimeter Array (SMA) and follow-up short spacing information was obtained with the IRAM 30 m telescope. Additional data were taken at 3 mm ...

Accretion disks are invoked to explain a host of astrophysical phenomena, from protostellar objects to AGN. And yet the mechanism allowing accretion disks to operate are completely unknown. This proposal seeks to observe the smoking gun signature of magnetically--driven viscosity in accretion disks. ...

Cold steady-state disk wind theory from near Keplerian accretion disks requires a large scale magnetic field at near equipartition strength. However the minimum magnetization has never been tested. We investigate the time evolution of an accretion disk threaded by a weak vertical magnetic field. The strength of the field is such that the disk magnetization ...

(LAMAS) Reveals Small�Scale Outflow Structure in Quasars # W. A. Barkhouse, P. J. Green, et al. 2006, Ap Tracing the Accretion History of the Red Galaxy Population # J. D. Silverman, P. J. Green, et al. 2005 Ap. Green, et al. 2005 ApJ, 618, 123 Hard X�Ray Emitting Active Galactic Nuclei Selected by the Chandra

(LAMAS) Reveals Small-Scale Outflow Structure in Quasars W. A. Barkhouse, P. J. Green, et al. 2006, Ap Tracing the Accretion History of the Red Galaxy Population J. D. Silverman, P. J. Green, et al. 2005 Ap. Green, et al. 2005 ApJ, 618, 123 Hard X-Ray Emitting Active Galactic Nuclei Selected by the Chandra

Cygnus X-1 was observed in the high state at the conjunction orbital phase (0) with the Chandra High Energy Transmission Grating (HETG). Strong and asymmetric absorption lines of cighly ionized species were detected, such as Fe xxv, Fe XXIV, Fe XXIII, Si ...

The outbursts of dwarf novae are suggested as being due to the liberation of energy in the accretion disk surrounding the white dwarf component following unstable mass outflow by the red companion. The periodicities observed in dwarf novae near maximum light are shown to be consistent with periodic eclipses of temperature fluctuations in the ...

Active galactic nuclei are the most powerful, long-lived objects in the Universe. Recent data confirm the theoretical idea that the power source is accretion into a massive black hole. The common occurrence of obscuration and outflows probably means that the contribution of active galactic nuclei to the power density of the Universe has been generally ...

Highly ionized fast accretion disc winds have been suggested as an explanation for a variety of observed absorption and emission features in the X-ray spectra of active galactic nuclei. Simple estimates have suggested that these flows may be massive enough to carry away a significant fraction of the accretion energy and could be involved in creating the ...

We present the results of a uniform and systematic search for blueshifted Fe K absorption lines in the X-ray spectra of five bright broad-line radio galaxies observed with Suzaku. We detect, for the first time in radio-loud active galactic nuclei (AGNs) at X-rays, several absorption lines at energies greater than 7 keV in three out of five sources, namely, 3C 111, 3C 120, and 3C 390.3. The lines ...

The sawtooth mode of convection of Earth's magnetosphere is a 2- to 4-hour planetary-scale oscillation powered by the solar wind-magnetosphere-ionosphere (SW-M-I) interaction. Using global simulations of geospace, we have shown that ionospheric O(+) outflows can generate sawtooth oscillations. As the outflowing ions fill the inner magnetosphere, their ...

The sawtooth mode of convection of Earth�s magnetosphere is a 2- to 4-hour planetary-scale oscillation powered by the solar wind�magnetosphere�ionosphere (SW-M-I) interaction. Using global simulations of geospace, we have shown that ionospheric O+ outflows can generate sawtooth oscillations. As the outflowing ions fill the inner magnetosphere, their ...

Using data from the Rossi X-Ray Timing Explorer, we investigate the spectral evolution along a "Z" track and a "?" track on the hardness-intensity diagrams of the first transient Z source XTE J1701�462. The spectral analyses suggest that the inner disk radius depends on the mass accretion rate, in agreement with the model prediction, R_in \\propto {\\dot{M}_disk}^{2/7}, for ...

In the last several years, multiwavelength monitoring programs have allowed us to develop a general description of the observational characteristics of accreting black holes as they journey through their outburst cycles. Driven seemingly to a large extent by the accretion rate, these sources display an almost predictable series of physical changes which ...

Jets and outflows are observed around a wide variety of accreting objects and seem to be a near-ubiquitous feature of accretion disks. Large-scale magnetic fields are often thought necessary for jet formation, but a longstanding puzzle is that the turbulence which is responsible for inward disk accretion should be ...

We perform multidimensional radiative transfer simulations to compute spectra for a hydrodynamical simulation of a line-driven accretion disc wind from an active galactic nucleus. The synthetic spectra confirm expectations from parametrized models that a disc wind can imprint a wide variety of spectroscopic signatures including narrow absorption lines, broad emission lines and ...

Detached, symbiotic binaries are generally assumed to interact via Bondi-Hoyle-Littleton (BHL) wind accretion. However, the accretion rates and outflow geometries that result from this mass-transfer mechanism cannot adequately explain the observations of the nearest and best studied symbiotic binary, Mira, or the formation of some ...

Stars with masses in the range 1-8 solar masses (M(\\circ)) live ordinary lives for approximately 10(9)-10(10) years, but die extraordinary deaths. First, during their death throes as asymptotic giant branch (AGB) stars they eject, over 10(4)-10(5) years, half or more of their mass in slowly expanding, spherical winds, and then, in a short (a few 100-1,000 years) and poorly understood phase, they ...

The self-sustained turbulence that develops in magnetized accretion disks is suppressed in the weakly ionized, quiescent disks of close binary stars. Because accretion still proceeds during quiescence, another viscosity mechanism operates in these systems. An anticorrelation of the recurrence times of SU UMa dwarf novae with their mass ratio supports ...

Accretional temperature profiles for Saturn�s large moon Titan are used to determine the conditions needed for accretion to avoid global melting as a function of the timing, duration, and nebular conditions of Titan�s accretion. We find that Titan can accrete undifferentiated in a �gas-starved� disk even ...

Many accreting neutron stars do so intermittently; that is, the accretion ceases for long quiescent intervals. During the accretion outburst, reactions are induced in the crust by the continual accumulation of matter. These reactions heat the crust out of thermal equilibrium with the core, and when ...

Many accreting neutron stars do so intermittently; that is, the accretion ceases for long quiescent intervals. During the accretion outburst, reactions are induced in the crust by the continual accumulation of matter. These reactions heat the crust out of thermal equilibrium with the core, and when ...

Mergers of supermassive black hole binaries release peak power of up to approximately 10(57) erg s(-1) in gravitational waves (GWs). As the GWs propagate through ambient gas, they induce shear and a small fraction of their power is dissipated through viscosity. The dissipated heat appears as electromagnetic (EM) radiation, providing a prompt EM counterpart to the GW signal. ...

The collapse of rotating magnetized molecular cloud cores is studied with axisymmetric magnetohydrodynamic (MHD) simulations. Because of the change of the equation of state of the interstellar gas, molecular cloud cores experience several phases during the collapse. In the earliest isothermal runaway collapse (n<~1010 H2 cm-3), a pseudodisk is formed, and it continues to contract until an ...