ALMA Imaging of a Galactic Molecular Outflow in NGC 4945

We present the ALMA detection of molecular outflowing gas in the central regions of NGC 4945, one of the nearest starbursts and also one of the nearest hosts of an active galactic nucleus (AGN). We detect four outflow plumes in CO J = 3 − 2 at ∼0.″3 resolution that appear to correspond to molecular gas located near the edges of the known ionized outflow cone and its (unobserved) counterpart behind the disk. The fastest and brightest of these plumes has emission reaching observed line-of-sight projected velocities of over 450 km s−1 beyond systemic, equivalent to an estimated physical outflow velocity v ≳ 600 km s−1 for the fastest emission. Most of these plumes have corresponding emission in HCN or HCO+ J = 4 − 3. We discuss a kinematic model for the outflow emission where the molecular gas has the geometry of the ionized gas cone and shares the rotation velocity of the galaxy when ejected. We use this model to explain the velocities we observe, constrain the physical speed of the ejected material, and account for the fraction of outflowing gas that is not detected due to confusion with the galaxy disk. We estimate a total molecular mass outflow rate M ̇ mol ∼ 20 M ⊙ yr−1 flowing through a surface within 100 pc of the disk midplane, likely driven by a combination of the central starburst and AGN.

Point-wise Self-similar Solution for Spiral Shocks in an Accretion Disk with Mass Outflow in a Binary

We examine the properties of spiral shocks from a steady, adiabatic, non-axisymmetric accretion disk around a compact star in a binary. We first incorporate all possible influences from a binary through adopting the Roche potential and Coriolis forces in the basic conservation equations. In this paper, we assume spiral shocks to be point-wise and self-similar, and that the flow is in vertical hydrostatic equilibrium to simplify the study. We also investigate mass outflow due to shock compression and apply it to an accreting white dwarf in a binary. We find that our model will be beneficial for overcoming the ad hoc assumption of an optically thick wind generally used in studies of the progenitors of supernovae Ia.

Reducing the Outflow of CBRN Soldiers from the Perspective of Motivation

Outflow itself and the turnover of personnel are natural phenomena and occur in any organisation. The motivational factors influencing outflow can be classified as financial, medical and psychological factors. Compared with the two other factors, the psychological factor is the most complex one. In the research, the author examined these psychological factors among the soldiers of the HDF 93rd CBRN Battalion in 2008 and in 2018 and compared the differences. The author also analysed the relationship between salary-motivated outflow and age, defining a key amount that should be taken into consideration in order to prevent the mass outflow.

A maximum X-ray luminosity scale of disc-dominated tidal destruction events

We develop a model describing the dynamical and observed properties of disc-dominated TDEs around black holes with the lowest masses (M ≲ few × 106M⊙). TDEs around black holes with the lowest masses are most likely to reach super-Eddington luminosities at early times in their evolution. By assuming that the amount of stellar debris which can form into a compact accretion disc is set dynamically by the Eddington luminosity, we make a number of interesting and testable predictions about the observed properties of bright soft-state X-ray TDEs and optically bright, X-ray dim TDEs. We argue that TDEs around black holes of the lowest masses will expel the vast majority of their gravitationally bound debris into a radiatively driven outflow. A large-mass outflow will obscure the innermost X-ray producing regions, leading to a population of low black hole mass TDEs which are only observed at optical & UV energies. TDE discs evolving with bolometric luminosities comparable to their Eddington luminosity will have near constant (i.e. black hole mass independent) X-ray luminosities, of order LX, max ≡ LM ∼ 1043 − 1044 erg/s. The range of luminosity values stems primarily from the range of allowed black hole spins. A similar X-ray luminosity limit exists for X-ray TDEs in the hard (Compton scattering dominated) state, and we therefore predict that the X-ray luminosity of the brightest X-ray TDEs will be at the scale LM(a) ∼ 1043 − 1044 erg/s, independent of black hole mass and accretion state. These predictions are in strong agreement with the properties of the existing population (∼40 sources) of observed TDEs.

Gauging the effect of Supermassive Black Holes feedback on Quasar host galaxies

In order to gauge the role that active galactic nuclei (AGN) play in the evolution of galaxies via the effect of kinetic feedback in nearby QSO 2’s (z ∼ 0.3), we observed eight such objects with bolometric luminosities $L_{bol} \sim 10^{46}\rm {erg\, s^{-1}}$ using Gemini GMOS-IFU’s. The emission lines were fitted with at least two Gaussian curves, the broadest of which we attributed to gas kinetically disturbed by an outflow. We found that the maximum extent of the outflow ranges from ∼1 to 8 kpc, being ∼ 0.5 ± 0.3 times the extent of the [O iii] ionized gas region. Our ‘default’ assumptions for the gas density (obtained from the [S ii] doublet) and outflow velocities resulted in peak mass outflow rates of $\dot{M}_{out}^{{\tt def}}\sim$ 3 – 30 $\rm {M_{\odot }}\, yr^{-1}$ and outflow power of $\dot{E}_{out}^{{\tt def}}\sim \, 10^{41}$ – 1043 erg s−1. The corresponding kinetic coupling efficiencies are $\varepsilon _f^{{\tt def}}=\dot{E}_{out}^{{\tt def}}/L_{bol}\, \sim 7\times 10^{-4}$ – 0.5 %, with the average efficiency being only 0.06 % (0.01 % median), implying little feedback powers from ionized gas outflows in the host galaxies. We investigated the effects of varying assumptions and calculations on $\dot{M}_{out}$ and $\dot{E}_{out}$ regarding the ionized gas densities, velocities, masses and inclinations of the outflow relative to the plane of the sky, resulting in average uncertainties of one dex. In particular, we found that better indicators of the [O iii] emitting gas density than the default [S ii] line ratio, such as the [Ar iv]λλ4711,40 line ratio, result in almost an order of magnitude decrease in the ϵf.

Carbon-chain molecule survey toward four low-mass molecular outflow sources

We performed a carbon-chain molecule (CCM) survey toward four low-mass outflow sources, IRAS 04181+2655 (I04181), HH211, L1524, and L1598, using the 13.7 m telescope at the Purple Mountain Observatory (PMO) and the 65 m Tian Ma Radio telescope at the Shanghai Observatory. We observed the following hydrocarbons (C2H, C4H, c–C3H2), HC2n+1N (n = 1, 2), CnS (n = 2, 3), and SO, HNC, N2H+. Hydrocarbons and HC3N were detected in all the sources, except for L1598, which had a marginal detection of C4H and a non-detection of HC3N (J = 2–1). HC5N and CCCS were only detected in I04181 and L1524, whereas SO was only detected in HH211. L1598 exhibits the lowest detection rate of CCMs and is generally regarded to be lacking in CCMs source. The ratio of N(HC3N/N(N2H+)) increases with evolution in low-mass star-forming cores. I04181 and L1524 are carbon-chain-rich star-forming cores that may possibly be characterized by warm carbon-chain chemistry. In I04181 and L1524, the abundant CCCS can be explained by shocked carbon-chain chemistry. In HH211, the abundant SO suggests that SO is formed by sublimated S+. In this study, we also mapped HNC, C4H, c–C3H2, and HC3N with data from the PMO. We also find that HNC and NH3 are concentrated in L1524S and L1524N, respectively. Furthermore, we discuss the chemical differences between I04181SE and I04181W. The co-evolution between linear hydrocarbon and cyanopolyynes can be seen in I04181SE.

The spacecraft wake as a tool to detect cold ions: Turning a problem into a feature

<p>Wakes behind scientific spacecraft caused by supersonic drifting ions is common in collisionless plasmas. Such wakes change the local plasma conditions and disturb in situ observations of the geophysical plasma parameters. We concentrate on observations of the electric field with double-probe instruments. Sometimes the wake effects are caused by the spacecraft body, are minor and easy to detect, and can be compensated for in a reasonable way. We show an example from the Cluster spacecraft in the solar wind. Sometimes the effects are caused by an electrostatic structure around a positively charged spacecraft causing an enhanced wake and major effects on the local plasma. Here observations of the geophysical electric field with the double-probe technique becomes impossible. Rather, the wake can be used to detect the presence of cold positive ions. Together with other instruments, also the cold ion flux can be estimated. We discuss such examples from the Cluster spacecraft in the magnetospheric lobes. For an intermediate range of parameters, when the drift energy of the ions is comparable to the equivalent charge of the spacecraft, also the charged wire booms of a double-probe instrument must be taken into account to extract useful information from the observations. We show an example from the MMS spacecraft near the magnetopause. With understanding of the physics causing wakes behind spacecraft, the local effects can sometimes be compensated for. When this is not possible, sometimes entirely new geophysical parameters can be estimated. An example is the flux of cold positive ions, constituting a major part of the mass outflow from planet Earth, using electric and magnetic field instruments on a spacecraft charged due to photoionization</p><p> </p>

Simulating the formation of η Carinae’s surrounding nebula through unstable triple evolution and stellar merger-induced eruption

ABSTRACT η Carinae is an extraordinary massive star famous for its 19th century Great Eruption and the surrounding Homunculus nebula ejected in that event. The cause of this eruption has been the centre of a long-standing mystery. Recent observations, including light-echo spectra of the eruption, suggest that it most likely resulted from a stellar merger in an unstable triple system. Here we present a detailed set of theoretical calculations for this scenario; from the dynamics of unstable triple systems and the mass ejection from close binary encounters, to the mass outflow from the eruption caused by the stellar merger and the post-merger wind phase. In our model the bipolar post-merger wind is the primary agent for creating the Homunculus, as it sweeps up external eruption ejecta into a thin shell. Our simulations reproduce many of the key aspects of the shape and kinematics of both the Homunculus nebula and its complex surrounding structure, providing strong support for the merger-in-a-triple scenario.

Unravelling the physics of multiphase AGN winds through emission line tracers

ABSTRACT Observations of emission lines in active galactic nuclei (AGNs) often find fast (∼1000 km s−1) outflows extending to kiloparsec scales, seen in ionized, neutral atomic and molecular gas. In this work we present radiative transfer calculations of emission lines in hydrodynamic simulations of AGN outflows driven by a hot wind bubble, including non-equilibrium chemistry, to explore how these lines trace the physical properties of the multiphase outflow. We find that the hot bubble compresses the line-emitting gas, resulting in higher pressures than in the ambient interstellar medium or that would be produced by the AGN radiation pressure. This implies that observed emission line ratios such as [O iv]$_{25 \, \rm {\mu m}}$ / [Ne ii]$_{12 \, \rm {\mu m}}$, [Ne v]$_{14 \, \rm {\mu m}}$ / [Ne ii]$_{12 \, \rm {\mu m}}$, and [N iii]$_{57 \, \rm {\mu m}}$ / [N ii]$_{122 \, \rm {\mu m}}$ constrain the presence of the bubble and hence the outflow driving mechanism. However, the line-emitting gas is under-pressurized compared to the hot bubble itself, and much of the line emission arises from gas that is out of pressure, thermal and/or chemical equilibrium. Our results thus suggest that assuming equilibrium conditions, as commonly done in AGN line emission models, is not justified if a hot wind bubble is present. We also find that ≳50 per cent of the mass outflow rate, momentum flux, and kinetic energy flux of the outflow are traced by lines such as [N ii]$_{122 \, \rm {\mu m}}$ and [Ne iii]$_{15 \, \rm {\mu m}}$ (produced in the 10$^{4} \, \rm {K}$ phase) and [C ii]$_{158 \, \rm {\mu m}}$ (produced in the transition from 10$^{4} \, \rm {K}$ to 100 K).