scholarly journals AGN and Star Formation Feedback in Galaxy Outflows

2018 ◽  
Vol 14 (S342) ◽  
pp. 229-233
Author(s):  
Elisabete M. de Gouveia Dal Pino ◽  
William Clavijo-Bohórquez ◽  
Claudio Melioli
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Three Dimensional ◽  
Active Galaxies ◽  
Opening Angle ◽  
Mass Loading ◽  
Nuclear Region ◽  
Molecular Outflows ◽  
Mhd Simulations ◽  
Large Opening

AbstractLarge-scale, broad outflows are common in active galaxies. In systems where star formation coexists with an AGN, it is unclear yet the role that both play on driving the outflows. In this work we present three-dimensional radiative-cooling MHD simulations of the formation of these outflows, considering the feedback from both the AGN and supernovae-driven winds. We find that a large-opening-angle AGN wind develops fountain structures that make the expanding gas to fallback. Furthermore, it exhausts the gas near the nuclear region, extinguishing star formation and accretion within a few 100.000 yr, which establishes the duty cycle of these outflows. The AGN wind accounts for the highest speed features in the outflow with velocities around 10.000 km s−1 (as observed in UFOs), but these are not as cold and dense as required by observations of molecular outflows. The SNe-driven wind is the main responsible for the observed mass-loading of the outflows.

scholarly journals Simulations of the star-forming molecular gas in an interacting M51-like galaxy

2020 ◽  
Vol 492 (2) ◽  
pp. 2973-2995 ◽  
Author(s):  
Robin G Tress ◽  
Rowan J Smith ◽  
Mattia C Sormani ◽  
Simon C O Glover ◽  
Ralf S Klessen ◽  
...  
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Formation Rate ◽  
Three Dimensional ◽  
Molecular Gas ◽  
Secondary Importance ◽  
Star Forming ◽  
The Galaxy ◽  
Cold Star ◽  
Self Gravity

ABSTRACT We present here the first of a series of papers aimed at better understanding the evolution and properties of giant molecular clouds (GMCs) in a galactic context. We perform high-resolution, three-dimensional arepo simulations of an interacting galaxy inspired by the well-observed M51 galaxy. Our fiducial simulations include a non-equilibrium, time-dependent, chemical network that follows the evolution of atomic and molecular hydrogen as well as carbon and oxygen self-consistently. Our calculations also treat gas self-gravity and subsequent star formation (described by sink particles), and coupled supernova feedback. In the densest parts of the simulated interstellar medium (ISM), we reach sub-parsec resolution, granting us the ability to resolve individual GMCs and their formation and destruction self-consistently throughout the galaxy. In this initial work, we focus on the general properties of the ISM with a particular focus on the cold star-forming gas. We discuss the role of the interaction with the companion galaxy in generating cold molecular gas and controlling stellar birth. We find that while the interaction drives large-scale gas flows and induces spiral arms in the galaxy, it is of secondary importance in determining gas fractions in the different ISM phases and the overall star formation rate. The behaviour of the gas on small GMC scales instead is mostly controlled by the self-regulating property of the ISM driven by coupled feedback.

scholarly journals Near-infrared observations of star formation and gas flows in the NUGA galaxy NGC 1365

2019 ◽  
Vol 622 ◽  
pp. A128 ◽  
Author(s):  
Nastaran Fazeli ◽  
Gerold Busch ◽  
Mónica Valencia-S. ◽  
Andreas Eckart ◽  
Michal Zajaček ◽  
...  
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Galaxy Evolution ◽  
Large Scale ◽  
Near Infrared ◽  
Molecular Gas ◽  
Nuclear Region ◽  
Stellar Kinematics ◽  
Hydrogen Recombination ◽  
Ngc 1365

In the framework of understanding the gas and stellar kinematics and their relations to AGNs and galaxy evolution scenarios, we present spatially resolved distributions and kinematics of the stars and gas in the central ∼800 pc radius of the nearby Seyfert galaxy NGC 1365. We obtained H + K- and K-band near-infrared (NIR) integral-field observations from VLT/SINFONI. Our results reveal strong broad and narrow emission-line components of ionized gas (hydrogen recombination lines Paα and Brγ) in the nuclear region, as well as hot dust with a temperature of ∼1300 K, both typical for type-1 AGNs. From MBH − σ* and the broad components of hydrogen recombination lines, we find a black-hole mass of (5 − 10)×106 M⊙. In the central ∼800 pc, we find a hot molecular gas mass of ∼615 M⊙, which corresponds to a cold molecular gas reservoir of (2 − 8)×108 M⊙. However, there is a molecular gas deficiency in the nuclear region. The gas and stellar-velocity maps both show rotation patterns consistent with the large-scale rotation of the galaxy. However, the gaseous and stellar kinematics show deviations from pure disk rotation, which suggest streaming motions in the central < 200 pc and a velocity twist at the location of the ring which indicates deviations in disk and ring rotation velocities in accordance with published CO kinematics. We detect a blueshifted emission line split in Paα, associated with the nuclear region only. We investigate the star-formation properties of the hot spots in the circumnuclear ring which have starburst ages of ≲10 Myr and find indications for an age gradient on the western side of the ring. In addition, our high-resolution data reveal further substructure within this ring which also shows enhanced star forming activity close to the nucleus.

scholarly journals Feedback Regulated Turbulence, Magnetic Fields, and Star Formation Rates in Galactic Disks

2015 ◽  
Vol 11 (S315) ◽  
pp. 38-41
Author(s):  
Chang-Goo Kim ◽  
Eve C. Ostriker
Keyword(s):  
Star Formation ◽  
Magnetic Fields ◽  
Formation Rate ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Quasi Equilibrium ◽  
Galactic Disks ◽  
Heating Rates ◽  
Mhd Simulations ◽  
Vertical Support

AbstractWe use three-dimensional magnetohydrodynamic (MHD) simulations to investigate the quasi-equilibrium states of galactic disks regulated by star formation feedback. We incorporate effects from massive-star feedback via time-varying heating rates and supernova (SN) explosions. We find that the disks in our simulations rapidly approach a quasi-steady state that satisfies vertical dynamical equilibrium. The star formation rate (SFR) surface density self-adjusts to provide the total momentum flux (pressure) in the vertical direction that matches the weight of the gas. We quantify feedback efficiency by measuring feedback yields, ηc≡ Pc/ΣSFR (in suitable units), for each pressure component. The turbulent and thermal feedback yields are the same for HD and MHD simulations, ηth ~ 1 and ηturb ~ 4, consistent with the theoretical expectations. In MHD simulations, turbulent magnetic fields are rapidly generated by turbulence, and saturate at a level corresponding to ηmag,t ~ 1. The presence of magnetic fields enhances the total feedback yield and therefore reduces the SFR, since the same vertical support can be supplied at a smaller SFR. We suggest further numerical calibrations and observational tests in terms of the feedback yields.

scholarly journals Three-Dimensional Global MHD Simulations of Magnetised Accretion Disks and Jets

1997 ◽  
Vol 163 ◽  
pp. 443-447 ◽  
Author(s):  
R. Matsumoto ◽  
K. Shibata
Keyword(s):  
Surface Layer ◽  
Magnetic Fields ◽  
Accretion Disks ◽  
Large Scale ◽  
Three Dimensional ◽  
Maximum Speed ◽  
Jet Formation ◽  
Mhd Simulations ◽  
Avalanche Flow ◽  
Magnetic Braking

AbstractWe carried out three-dimensional global MHD simulations of jet formation from an accretion disk threaded by large-scale magnetic fields. Numerical results show that bipolar jets with maximum speed υjet ~ υKepler are created. The surface layer of the disk accretes faster than the equatorial part because magnetic braking most effectively affects that layer. Accretion proceeds along spiral channels which correspond to the surface avalanche flow appearing in previous axisymmetric simulations. Spirally shaped low β (= Pgas/Pmag < 1) regions appear in the innermost part of accretion disks where toroidal magnetic fields become dominant.

scholarly journals Stellar Explosions in High-surface Density Galaxies

2015 ◽  
Vol 11 (A29B) ◽  
pp. 232-232
Author(s):  
Evan Scannapieco ◽  
Sharanya Sur ◽  
Eve C. Ostriker
Keyword(s):  
Star Formation ◽  
Surface Density ◽  
Energy Input ◽  
Large Scale ◽  
Star Formation Rate ◽  
High Surface ◽  
Formation Rate ◽  
Three Dimensional ◽  
Velocity Dispersions ◽  
The Impact

AbstractHigh surface density, rapidly star-forming galaxies are observed to have ≈ 50 - 100 km s−1 line-of-sight velocity dispersions, which are much higher than expected from supernova driving alone, but may arise from large-scale gravitational instabilities. Using three-dimensional simulations of local regions of the interstellar medium, we explore the impact of high velocity dispersions that arise from these disk instabilities. Parametrizing disks by their surface densities and epicyclic frequencies, we conduct a series of simulations that probe a broad range of conditions. Turbulence is driven purely horizontally and on large scales, neglecting any energy input from supernovae.We find that such motions lead to strong global outflows in the highly-compact disks that were common at high redshifts, but weak or negligible mass loss in the more diffuse disks that are prevalent today. Substantial outflows are generated if the one-dimensional horizontal velocity dispersion exceeds -35 km s−1, as occurs in the dense disks that have star formation rate densities above ≈ 0.1 M⊙ yr−1 kpc−2. These outflows are triggered by a thermal runaway, arising from the inefficient cooling of hot material coupled with successive heating from turbulent driving. Thus, even in the absence of stellar feedback, a critical value of the star-formation rate density for outflow generation can arise due to a turbulent heating instability. This suggests that in strongly self-gravitating disks, outflows may be enhanced by, but need not caused by, energy input from stellar explosions.These results are explained in more detailed in Sur, Scannapieco, & Ostriker (2015).

scholarly journals The nature of a primary jet within a circumbinary disc outflow in a young stellar system

2020 ◽  
Vol 494 (2) ◽  
pp. 2299-2311
Author(s):  
Chris J R Lynch ◽  
Michael D Smith
Keyword(s):  
Ambient Medium ◽  
Stellar System ◽  
Three Dimensional ◽  
Pulse Amplitude ◽  
Young Star ◽  
Opening Angle ◽  
Molecular Outflow ◽  
Axis Alignment ◽  
Large Opening ◽  
Set Up

ABSTRACT Most stars form in binaries, and both stars may grow by accreting material from a circumbinary disc on to their own discs. We suspect that in many cases a wide molecular wind will envelope a collimated atomic jet emanating from close to an orbiting young star. This so-called circumbinary scenario is explored here in order to find common identifiable properties. The dynamical set-up is studied with three-dimensional simulations with chemistry and cooling included. We extract the properties on scales of order 100 au and compare to the co-orbital scenario in which the wind and jet sources are in orbit. We find that the rapid orbital motion generates a wide ionized sheath around the jet core with a large opening angle at the base. This is independent of the presence of the surrounding molecular outflow. However, the atomic jet is recollimated beyond ∼55 au when the molecular outflow restricts the motion of the ambient medium which, in turn, confines the jet. These physical properties are related to the optical H α imaging, providing a means of distinguishing between models. The high excitation sheath and recollimation region can be explored on these scales through the next generation of instruments. However, in general, the amount and location of the ionized material, whether in the knots or the sheath, will depend on several parameters including the orbital period, axis alignment, and pulse amplitude.

scholarly journals Three-dimensional MHD simulations of molecular cloud fragmentation regulated by gravity, ambipolar diffusion, and turbulence

2008 ◽  
Vol 4 (S259) ◽  
pp. 115-116
Author(s):  
Takahiro Kudoh ◽  
Shantanu Basu
Keyword(s):  
Star Formation ◽  
Magnetic Fields ◽  
Time Scale ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Three Dimensional ◽  
Core Formation ◽  
Mhd Simulations ◽  
Dimensional Simulation

AbstractWe find that the star formation is accelerated by the supersonic turbulence in the magnetically dominated (subcritical) clouds. We employ a fully three-dimensional simulation to study the role of magnetic fields and ion-neutral friction in regulating gravitationally driven fragmentation of molecular clouds. The time-scale of collapsing core formation in subcritical clouds is a few ×107 years when starting with small subsonic perturbations. However, it is shortened to approximately several ×106 years by the supersonic flows in the clouds. We confirm that higher-spacial resolution simulations also show the same result.

scholarly journals Following the gas flows from nuclear spirals to the accretion disk

2006 ◽  
Vol 2 (S238) ◽  
pp. 283-286
Author(s):  
Thaisa Storchi-Bergmann
Keyword(s):  
Accretion Disk ◽  
Large Scale ◽  
Active Galaxies ◽  
Stellar Disk ◽  
Recent Analysis ◽  
Nuclear Region ◽  
Gas Kinematics ◽  
Evolutionary Scenario ◽  
Optical Images ◽  
The One

AbstractA recent analysis of HST optical images of 34 nearby early-type active galaxies and of a matched sample of 34 inactive galaxies – both drawn from the Palomar survey – shows a clear excess of nuclear dusty structures (filaments, spirals and disks) in the active galaxies. This result supports the association of the dusty structures with the material which feeds the supermassive black hole (hereafter SMBH). Among the inactive galaxies there is instead an excess of nuclear stellar disks. As the active and inactive galaxies can be considered two phases of the “same” galaxy, the above findings and dust morphologies suggest an evolutionary scenario in which external material (gas and dust) is captured to the nuclear region where it settles and ends up feeding the active nucleus and replenishing the stellar disk – which is hidden by the dust in the active galaxies – with new stars. This evolutionary scenario is supported by recent gas kinematics of the inner few hundred parsecs of NGC 1097, which shows streaming motions (with velocities ∼50 km s−1) towards the nucleus along spiral arms. The implied large scale mass accretion rate is much larger than the one derived in previous studies for the nuclear accretion disk, but is just enough to accumulate one million solar masses over a few million years in the nuclear region, thus consistent with the recent finding of a young circumnuclear starburst of one million solar masses within 9 parsecs from the nucleus in this galaxy.

scholarly journals MHD simulations of supernova driven ISM turbulence

2006 ◽  
Vol 2 (S237) ◽  
pp. 415-415
Author(s):  
Oliver Gressel ◽  
Udo Ziegler
Keyword(s):  
Magnetic Fields ◽  
Dynamic Process ◽  
Large Scale ◽  
Three Dimensional ◽  
Rotational Instability ◽  
Dynamic Evolution ◽  
Mhd Simulations ◽  
Mhd Model

AbstractLarge-scale magnetic fields, that can be observed in numerous galaxies, are most likely the outcome of a dynamic process, a so-called dynamo. The favoured mechanisms for driving such a process in the ISM are supernovae (SNe) and/or magneto-rotational instability (MRI). In this work we simulate the dynamic evolution of the turbulent ISM utilising a three-dimensional MHD model.

scholarly journals Cloud G074.11+00.11: a stellar cluster in formation

2019 ◽  
Vol 630 ◽  
pp. A69
Author(s):  
Mika Saajasto ◽  
Jorma Harju ◽  
Mika Juvela ◽  
Liu Tie ◽  
Qizhou Zhang ◽  
...  
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Three Dimensional ◽  
Central Star ◽  
Small Scale ◽  
Molecular Line ◽  
Filamentary Structure ◽  
Maser Emission ◽  
Stellar Cluster ◽  
Star Forming

Context. We present molecular line and dust continuum observations of a Planck-detected cold cloud, G074.11+00.11. The cloud consists of a system of curved filaments and a central star-forming clump. The clump is associated with several infrared sources and H2O maser emission. Aims. We aim to determine the mass distribution and gas dynamics within the clump to investigate if the filamentary structure seen around the clump repeats itself on a smaller scale, and to estimate the fractions of mass contained in dense cores and filaments. The velocity distribution of pristine dense gas can be used to investigate the global dynamical state of the clump, the role of filamentary inflows, filament fragmentation, and core accretion. Methods. We used molecular line and continuum observations from single dish observatories and interferometric facilities to study the kinematics of the region. Results. The molecular line observations show that the central clump may have formed as a result of a large-scale filament collision. The central clump contains three compact cores. Assuming a distance of 2.3 kpc, based on Gaia observations and a three-dimensional extinction method of background stars, the mass of the central clump exceeds 700 M⊙, which is roughly ~25% of the total mass of the cloud. Our virial analysis suggests that the central clump and all identified substructures are collapsing. We find no evidence for small-scale filaments associated with the cores. Conclusions. Our observations indicate that the clump is fragmented into three cores with masses in the range [10, 50] M⊙ and that all three are collapsing. The presence of an H2O maser emission suggests active star formation. However, the CO lines show only weak signs of outflows. We suggest that the region is young and any processes leading to star formation have just recently begun.

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