scholarly journals Dense gas formation and destruction in a simulated Perseus-like galaxy cluster with spin-driven black hole feedback

2019 ◽  
Vol 631 ◽  
pp. A60 ◽  
Author(s):  
R. S. Beckmann ◽  
Y. Dubois ◽  
P. Guillard ◽  
P. Salome ◽  
V. Olivares ◽  
...  
Keyword(s):  
Black Hole ◽  
Adaptive Mesh Refinement ◽  
Large Scale ◽  
Nearby Galaxy ◽  
Dense Gas ◽  
Cluster Galaxy ◽  
Spin Evolution ◽  
Local Ratio ◽  
Hydrodynamical Simulations ◽  
The Impact

Context. Extended filamentary Hα emission nebulae are a striking feature of nearby galaxy clusters but the formation mechanism of the filaments, and the processes which shape their morphology remain unclear. Aims. We conduct an investigation into the formation, evolution and destruction of dense gas in the centre of a simulated, Perseus-like, cluster under the influence of a spin-driven jet. The jet is powered by the supermassive black hole (SMBH) located in the cluster’s brightest cluster galaxy. We particularly study the role played by condensation of dense gas from the diffuse intracluster medium, and the impact of direct uplifting of existing dense gas by the jets, in determining the spatial distribution and kinematics of the dense gas. Methods. We present a hydrodynamical simulation of an idealised Perseus-like cluster using the adaptive mesh refinement code RAMSES. Our simulation includes a SMBH that self-consistently tracks its spin evolution via its local accretion, and in turn drives a large-scale jet whose direction is based on the black hole’s spin evolution. The simulation also includes a live dark matter (DM) halo, a SMBH free to move in the DM potential, star formation and stellar feedback. Results. We show that the formation and destruction of dense gas is closely linked to the SMBH’s feedback cycle, and that its morphology is highly variable throughout the simulation. While extended filamentary structures readily condense from the hot intra-cluster medium, they are easily shattered into an overly clumpy distribution of gas during their interaction with the jet driven outflows. Condensation occurs predominantly onto infalling gas located 5−15 kpc from the centre during quiescent phases of the central AGN, when the local ratio of the cooling time to free fall time falls below 20, i.e. when tcool/tff <  20. Conclusions. We find evidence for both condensation and uplifting of dense gas, but caution that purely hydrodynamical simulations struggle to effectively regulate the cluster cooling cycle and produce overly clumpy distributions of dense gas morphologies, compared to observation.

scholarly journals The Bardeen–Petterson effect in accreting supermassive black hole binaries: a systematic approach

2020 ◽  
Vol 496 (3) ◽  
pp. 3060-3075 ◽  
Author(s):  
Davide Gerosa ◽  
Giovanni Rosotti ◽  
Riccardo Barbieri
Keyword(s):  
Black Hole ◽  
Systematic Investigation ◽  
Stationary Solutions ◽  
Evolutionary Stage ◽  
Black Hole Binaries ◽  
Frame Dragging ◽  
Supermassive Black Hole ◽  
Complete Alignment ◽  
Hydrodynamical Simulations ◽  
The Impact

ABSTRACT Disc-driven migration is a key evolutionary stage of supermassive black hole binaries hosted in gas-rich galaxies. Besides promoting the inspiral, viscous interactions tend to align the spins of the black holes with the orbital angular momentum of the disc. We present a critical and systematic investigation of this problem, also known as the Bardeen–Petterson effect. We design a new iterative scheme to solve the non-linear dynamics of warped accretion discs under the influence of both relativistic frame dragging and binary companion. We characterize the impact of the disc ‘critical obliquity’, which marks regions of the parameter space where stationary solutions do not exist. We find that black hole spins reach either complete alignment or a critical configuration. Reaching the critical obliquity might imply that the disc breaks as observed in hydrodynamical simulations. Our findings are important to predict the spin configurations with which supermassive black hole binaries enter their gravitational-wave driven regime and become detectable by LISA.

scholarly journals The BAHAMAS project: effects of dynamical dark energy on large-scale structure

2020 ◽  
Vol 498 (2) ◽  
pp. 1576-1592 ◽  
Author(s):  
Simon Pfeifer ◽  
Ian G McCarthy ◽  
Sam G Stafford ◽  
Shaun T Brown ◽  
Andreea S Font ◽  
...  
Keyword(s):  
Dark Energy ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Large Scale Structure ◽  
Scale Structure ◽  
The Bahamas ◽  
Wide Range ◽  
Hydrodynamical Simulations ◽  
The Impact ◽  
Dynamical Dark Energy

ABSTRACT In this work, we consider the impact of spatially uniform but time-varying dark energy (or ‘dynamical dark energy’, DDE) on large-scale structure in a spatially flat universe, using large cosmological hydrodynamical simulations that form part of the BAHAMAS project. As DDE changes the expansion history of the universe, it impacts the growth of structure. We explore variations in DDE that are constrained to be consistent with the cosmic microwave background. We find that DDE can affect the clustering of matter and haloes at the $\sim 10{{\ \rm per\ cent}}$ level (suppressing it for so-called freezing models, while enhancing it for thawing models), which should be distinguishable with upcoming large-scale structure surveys. DDE cosmologies can also enhance or suppress the halo mass function (with respect to Lambda cold dark matter) over a wide range of halo masses. The internal properties of haloes are minimally affected by changes in DDE, however. Finally, we show that the impact of baryons and associated feedback processes is largely independent of the change in cosmology and that these processes can be modelled separately to typically better than a few per cent accuracy.

scholarly journals The Transition and Adoption to Modern Programming Concepts for Scientific Computing in Fortran

2007 ◽  
Vol 15 (1) ◽  
pp. 27-44 ◽  
Author(s):  
Charles D. Norton ◽  
Viktor K. Decyk ◽  
Boleslaw K. Szymanski ◽  
Henry Gardner
Keyword(s):  
Design Patterns ◽  
Adaptive Mesh Refinement ◽  
Large Scale ◽  
Object Oriented ◽  
Adaptive Mesh ◽  
Particle Simulation ◽  
Programming Techniques ◽  
Early Exploration ◽  
The Impact ◽  
Development Applications

This paper describes our experiences in the early exploration of modern concepts introduced in Fortran90 for large-scale scientific programming. We review our early work in expressing object-oriented concepts based on the new Fortran90 constructs – foreign to most programmers at the time – our experimental work in applying them to various applications, the impact on the WG5/J3 standards committees to consider formalizing object-oriented constructs for later versions of Fortran, and work in exploring how other modern programming techniques such as Design Patterns can and have impacted our software development. Applications will be drawn from plasma particle simulation and finite element adaptive mesh refinement for solid earth crustal deformation modeling.

scholarly journals On the phase-space structure of galaxy clusters from cosmological simulations

2020 ◽  
Vol 500 (3) ◽  
pp. 3462-3480
Author(s):  
I Marini ◽  
A Saro ◽  
S Borgani ◽  
G Murante ◽  
E Rasia ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Power Law ◽  
Space Structure ◽  
Cluster Galaxy ◽  
Phase Space Structure ◽  
Formation And Evolution ◽  
Hydrodynamical Simulations ◽  
Intracluster Light ◽  
Inner Region ◽  
The Impact

ABSTRACT Cosmological N-body simulations represent an excellent tool to study the formation and evolution of dark matter (DM) haloes and the mechanisms that have originated the universal profile at the largest mass scales in the Universe. In particular, the combination of the velocity dispersion σv with the density ρ can be used to define the pseudo-entropy $S(r)=\sigma _\mathrm{v}^2/\rho ^{\, 2/3}$, whose profile is well described by a simple power law $S\propto \, r^{\, \alpha }$. We analyse a set of cosmological hydrodynamical re-simulations of massive galaxy clusters and study the pseudo-entropy profiles as traced by different collisionless components in simulated galaxy clusters: DM, stars, and substructures. We analyse four sets of simulations, exploring different resolution and physics (N-body and full hydrodynamical simulations) to investigate convergence and the impact of baryons. We find that baryons significantly affect the inner region of pseudo-entropy profiles as traced by substructures, while DM particles profiles are characterized by an almost universal behaviour, thus suggesting that the level of pseudo-entropy could represent a potential low-scatter mass-proxy. We compare observed and simulated pseudo-entropy profiles and find good agreement in both normalization and slope. We demonstrate, however, that the method used to derive observed pseudo-entropy profiles could introduce biases and underestimate the impact of mergers. Finally, we investigate the pseudo-entropy traced by the stars focusing our interest in the dynamical distinction between intracluster light and the stars bound to the brightest cluster galaxy: the combination of these two pseudo-entropy profiles is well described by a single power law out to almost the entire cluster virial radius.

scholarly journals Intermittent planet migration and the formation of multiple dust rings and gaps in protoplanetary discs

2020 ◽  
Vol 493 (4) ◽  
pp. 5892-5912 ◽  
Author(s):  
Gaylor Wafflard-Fernandez ◽  
Clément Baruteau
Keyword(s):  
Large Scale ◽  
Continuum Emission ◽  
Post Processing ◽  
Dust Trapping ◽  
Time Migration ◽  
Gap Opening ◽  
Pressure Maximum ◽  
Hydrodynamical Simulations ◽  
The Impact ◽  
Protoplanetary Discs

ABSTRACT A key challenge for protoplanetary discs and planet formation models is to be able to make a reliable connection between observed structures in the discs emission, like bright and dark rings or asymmetries, and the supposed existence of planets triggering these structures. The observation of N dark rings of emission is often interpreted as evidence for the presence of N planets which clear dust gaps around their orbit and form dust-trapping pressure maxima in the disc. The vast majority of the models that studied the impact of planets on the dynamics of dust and gas in a protoplanetary disc assumed planets on fixed orbits. Here, we go a different route and examine how the large-scale inward migration of a single planet structures the dust content of a massive disc. In many circumstances, the migration of a partial gap-opening planet with a mass comparable to Saturn is found to run away intermittently. By means of 2D gas and dust hydrodynamical simulations, we show that intermittent runaway migration can form multiple dust rings and gaps across the disc. Each time migration slows down, a pressure maximum forms beyond the planet gap that traps the large dust. Post-processing of our simulations results with 3D dust radiative transfer calculations confirms that intermittent runaway migration can lead to the formation of multiple sets of bright and dark rings of continuum emission in the (sub)millimeter beyond the planet location.

scholarly journals Imprint of baryons and massive neutrinos on velocity statistics

2020 ◽  
Vol 644 ◽  
pp. A170
Author(s):  
Joseph Kuruvilla ◽  
Nabila Aghanim ◽  
Ian G. McCarthy
Keyword(s):  
Active Galactic Nuclei ◽  
Large Scale ◽  
Galactic Nuclei ◽  
Microwave Background ◽  
Velocity Statistics ◽  
Sunyaev Zel'dovich Effect ◽  
Massive Neutrinos ◽  
Hydrodynamical Simulations ◽  
The Impact ◽  
Velocity Bias

We explored the impact of baryonic effects (namely stellar and active galactic nuclei feedback) on the moments of pairwise velocity using the Illustris-TNG, EAGLE, cosmo-OWLS, and BAHAMAS suites of cosmological hydrodynamical simulations. The assumption that the mean pairwise velocity of the gas component follows that of the dark matter is studied here at small separations, and we find that even at pair separations of 10–20 h−1Mpc, there is a 4–5% velocity bias. At smaller separations, it gets larger with varying strength depending on the sub-grid prescription. By isolating different physical processes, our findings suggest that the large-scale velocity bias is mainly driven by stellar rather than active galactic nuclei feedback. If unaccounted for, this velocity offset could possibly bias cosmological constraints from the kinetic Sunyaev-Zel’dovich effect in future cosmic microwave background (CMB) surveys. Furthermore, we examined how the first and the second moment of the pairwise velocity are affected by both the baryonic and the neutrino free-streaming effects for both the matter and gas components. For both moments, we were able to disentangle the effects of baryonic processes from those of massive neutrinos; and for pair separations below 20 h−1Mpc, we find that these moments of the pairwise velocity decrease with increasing neutrino mass. Our work thus sets out a way in which the pairwise velocity statistics can be utilised to constrain the summed mass of neutrinos from future CMB surveys and peculiar velocity surveys.

scholarly journals Cosmic ray feedback from supernovae in dwarf galaxies

2020 ◽  
Vol 638 ◽  
pp. A123 ◽  
Author(s):  
Gohar Dashyan ◽  
Yohan Dubois
Keyword(s):  
Star Formation ◽  
Diffusion Coefficients ◽  
Adaptive Mesh Refinement ◽  
Large Scale ◽  
Dwarf Galaxies ◽  
Cosmic Ray ◽  
Adaptive Mesh ◽  
Galactic Winds ◽  
Mass Outflow ◽  
Hydrodynamical Simulations

The regulation of the baryonic content in dwarf galaxies is a long-standing problem. Supernovae (SNe) are supposed to play a key role in forming large-scale galactic winds by removing important amounts of gas from galaxies. SNe are efficient accelerators of non-thermal particles, so-called cosmic rays (CRs), which can substantially modify the dynamics of the gas and conditions to form large-scale galactic winds. We investigate how CR injection by SNe impacts the star formation and the formation of large-scale winds in dwarf galaxies, and whether it can produce galaxy star-formation rates (SFR) and wind properties closer to observations. We ran CR magneto-hydrodynamical simulations of dwarf galaxies at high resolution (9 pc) with the adaptive mesh refinement code RAMSES. Those disc galaxies are embedded in isolated halos of mass of 1010 and 1011 M⊙, and CRs are injected by SNe. We included CR isotropic and anisotropic diffusion with various diffusion coefficients, CR radiative losses, and CR streaming. The injection of CR energy into the interstellar medium smooths out the highest gas densities, which reduces the SFR by a factor of 2–3. Mass outflow rates are significantly greater with CR diffusion, by 2 orders of magnitudes for the higher diffusion coefficients. Without diffusion and streaming, CRs are inefficient at generating winds. CR streaming alone allows for the formation of winds but which are too weak to match observations. The formation of galactic winds strongly depends on the diffusion coefficient: for low coefficients, CR energy stays confined in high density regions where CR energy losses are highest, and higher coefficients, which allow for a more efficient leaking of CRs out of dense gas, produce stronger winds. CR diffusion leads to colder and denser winds than without CRs, and brings outflow rates and mass loading factors much closer to observations.

Central kiloparsec of NGC 1326 observed with SINFONI

2020 ◽  
Vol 638 ◽  
pp. A53
Author(s):  
Nastaran Fazeli ◽  
Gerold Busch ◽  
Andreas Eckart ◽  
Françoise Combes ◽  
Persis Misquitta ◽  
...  
Keyword(s):  
Black Hole ◽  
Galaxy Evolution ◽  
Near Infrared ◽  
Velocity Fields ◽  
Molecular Gas ◽  
Nearby Galaxy ◽  
Stellar Content ◽  
Stellar Rotation ◽  
Supermassive Black Hole ◽  
Integral Field Spectrograph

Gas inflow processes in the vicinity of galactic nuclei play a crucial role in galaxy evolution and supermassive black hole growth. Exploring the central kiloparsec of galaxies is essential to shed more light on this subject. We present near-infrared H- and K-band results of the nuclear region of the nearby galaxy NGC 1326, observed with the integral-field spectrograph SINFONI mounted on the Very Large Telescope. The field of view covers 9″ × 9″ (650 × 650 pc2). Our work is concentrated on excitation conditions, morphology, and stellar content. The nucleus of NGC 1326 was classified as a LINER, however in our data we observed an absence of ionised gas emission in the central r ∼ 3″. We studied the morphology by analysing the distribution of ionised and molecular gas, and thereby detected an elliptically shaped, circum-nuclear star-forming ring at a mean radius of 300 pc. We estimate the starburst regions in the ring to be young with dominating ages of < 10 Myr. The molecular gas distribution also reveals an elongated east to west central structure about 3″ in radius, where gas is excited by slow or mild shock mechanisms. We calculate the ionised gas mass of 8 × 105 M⊙ completely concentrated in the nuclear ring and the warm molecular gas mass of 187 M⊙, from which half is concentrated in the ring and the other half in the elongated central structure. The stellar velocity fields show pure rotation in the plane of the galaxy. The gas velocity fields show similar rotation in the ring, but in the central elongated H2 structure they show much higher amplitudes and indications of further deviation from the stellar rotation in the central 1″ aperture. We suggest that the central 6″ elongated H2 structure might be a fast-rotating central disc. The CO(3–2) emission observations with the Atacama Large Millimeter/submillimeter Array reveal a central 1″ torus. In the central 1″ of the H2 velocity field and residual maps, we find indications for a further decoupled structure closer to a nuclear disc, which could be identified with the torus surrounding the supermassive black hole.

Impact of COVID-19 on Nuclear Medicine in Germany, Austria and Switzerland: An International Survey in April 2020

2020 ◽  
Vol 59 (04) ◽  
pp. 294-299 ◽  
Author(s):  
Lutz S. Freudenberg ◽  
Ulf Dittmer ◽  
Ken Herrmann
Keyword(s):  
Nuclear Medicine ◽  
Health Systems ◽  
Personal Protective Equipment ◽  
Large Scale ◽  
Diagnostic Procedures ◽  
Protective Equipment ◽  
Current Crisis ◽  
Web Based ◽  
Public Versus Private ◽  
The Impact

Abstract Introduction Preparations of health systems to accommodate large number of severely ill COVID-19 patients in March/April 2020 has a significant impact on nuclear medicine departments. Materials and Methods A web-based questionnaire was designed to differentiate the impact of the pandemic on inpatient and outpatient nuclear medicine operations and on public versus private health systems, respectively. Questions were addressing the following issues: impact on nuclear medicine diagnostics and therapy, use of recommendations, personal protective equipment, and organizational adaptations. The survey was available for 6 days and closed on April 20, 2020. Results 113 complete responses were recorded. Nearly all participants (97 %) report a decline of nuclear medicine diagnostic procedures. The mean reduction in the last three weeks for PET/CT, scintigraphies of bone, myocardium, lung thyroid, sentinel lymph-node are –14.4 %, –47.2 %, –47.5 %, –40.7 %, –58.4 %, and –25.2 % respectively. Furthermore, 76 % of the participants report a reduction in therapies especially for benign thyroid disease (-41.8 %) and radiosynoviorthesis (–53.8 %) while tumor therapies remained mainly stable. 48 % of the participants report a shortage of personal protective equipment. Conclusions Nuclear medicine services are notably reduced 3 weeks after the SARS-CoV-2 pandemic reached Germany, Austria and Switzerland on a large scale. We must be aware that the current crisis will also have a significant economic impact on the healthcare system. As the survey cannot adapt to daily dynamic changes in priorities, it serves as a first snapshot requiring follow-up studies and comparisons with other countries and regions.

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