Rüstungskontrolle

Krause, Joachim

doi:10.1007/978-3-322-85140-6_42

Cited by 32 publications

(71 citation statements)

References 5 publications

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“…Interestingly, Jackson, Tadhunter & Sparks (1998) found a ring of young stars around the centre of Cygnus A, the most powerful radio source at low redshift (z = 0.056). They argue that the blue condensations are almost certainly due to young stars and not caused by scattering of the obscured quasar; the continuum energy distribution can be modelled by starburst activity much less than 1 Gyr ago, possibly an instantaneous burst with t ≤ 10 Myr, which is compatible with the radio source age of ∼10 7 yr (Krause 2005). Privon et al (2012) derive an overall SFR of 10-70 M yr −1 for Cygnus A.…”

Section: Comparison To Observationsmentioning

confidence: 87%

“…The most direct consequence of the blast wave is the formation of a cavity in the disc centre since the bow shock pushes intermediate density gas outwards. The expansion can be approximated by a spherical shape, and assuming a constant energy input by the jet, the blast wave evolution can then be described by the one given in Krause (2005), keeping in mind the expectable deviations due to the inhomogeneities in the disc. The blast wave expands until it leaves the disc vertically, and then venting its high pressure efficiently though this channel since the weaker density contrast there results in a faster jet propagation.…”

Section: Phase A: Formation Of a Central Cavitymentioning

confidence: 99%

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Jet-induced star formation in gas-rich galaxies

Gaibler¹,

Khochfar

Krause³

et al. 2012

Monthly Notices of the Royal Astronomical Society

244

261

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This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. ?? 2012 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. The version of record is available online at doi:10.1111/j.1365-2966.2012.21479.x.Feedback from active galactic nuclei (AGN) has become a major component in simulations of galaxy evolution, in particular for massive galaxies. AGN jets have been shown to provide a large amount of energy and are capable of quenching cooling flows. Their impact on the host galaxy, however, is still not understood. Subgrid models of AGN activity in a galaxy evolution context so far have been mostly focused on the quenching of star formation. To shed more light on the actual physics of the ???radio mode??? part of AGN activity, we have performed simulations of the interaction of a powerful AGN jet with the massive gaseous disc (1011 M) of a high-redshift galaxy. We spatially resolve both the jet and the clumpy, multi-phase interstellar medium (ISM) and include an explicit star formation model in the simulation. Following the system over more than 107 yr, we find that the jet activity excavates the central region, but overall causes a significant change to the shape of the density probability distribution function and hence the star formation rate due to the formation of a blast wave with strong compression and cooling in the ISM. This results in a ring- or disc-shaped population of young stars. At later times, the increase in star formation rate also occurs in the disc regions further out since the jet cocoon pressurizes the ISM. The total mass of the additionally formed stars may be up to 1010 M for one duty cycle. We discuss the details of this jet-induced star formation (positive feedback) and its potential consequences for galaxy evolution and observable signatures

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Section: Comparison To Observationsmentioning

confidence: 87%

Section: Phase A: Formation Of a Central Cavitymentioning

confidence: 99%

Jet-induced star formation in gas-rich galaxies

Gaibler¹,

Khochfar

Krause³

et al. 2012

Monthly Notices of the Royal Astronomical Society

244

261

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show abstract

“…This inflow motion could be associated with backflow of gas that was accelerated by Cen A's jet and after producing a bow shock is flowing back at the side of the jet cocoon, although on much larger scales, this phenomenon is seen in jet simulations (e.g., Krause 2005). As the gas is flowing back, it is reionized by radiation from the central source.…”

Section: Gas Kinematicsmentioning

confidence: 94%

The Central Parsecs of Centaurus A: High‐excitation Gas, a Molecular Disk, and the Mass of the Black Hole

Neumayer

Cappellari

Reunanen

et al. 2007

ApJ

144

242

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We present two-dimensional gas-kinematic maps of the central region in Centaurus A. The adaptive optics (AO) assisted SINFONI data from the VLT have a resolution of 0.12 00 in K band. The ionized gas species (Br, [Fe ii], [Si vi]) show a rotational pattern that is increasingly overlaid by nonrotational motion for higher excitation lines in the direction of Cen A's radio jet. The emission lines of molecular hydrogen (H 2 ) show regular rotation and no distortion due to the jet. The molecular gas seems to be well settled in the gravitational potential of the stars and the central supermassive black hole, and we thus use it as a tracer to model the mass in the central AE1.5 00 . These are the first AO integral-field observations on the nucleus of Cen A, enabling us to study the regularity of the rotation around the black hole, well inside the radius of influence, and to determine the inclination angle of the gas disk in a robust way. The gas kinematics are best modeled through a tilted-ring model that describes the warped gas disk; its mean inclination angle is $34 and the mean position angle of the major axis is $155 . The best-fit black hole mass is M BH ¼ (4:5 þ1:7 À1:0 ) ; 10 7 M (3 error), based on a kinematically hot disk model where the velocity dispersion is included through the Jeans equation. This black hole mass estimate is somewhat lower than, but consistent with, the mass values previously derived from ionized gas kinematics. It is also consistent with the stellar dynamical measurement from the same AO observations, which we present in a separate paper. It brings Cen A into agreement with the M BH -relation.

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“…It is becoming increasingly clear, from both observational and theoretical works, that radio sources have a significant impact on their environment. They push aside the intracluster gas, producing X-ray cavities (Carilli, Perley & Harris 1994;Alexander 2002;Smith et al 2002;Zanni et al 2003;Krause 2005;McNamara et al 2005;Nulsen et al 2005). The associated heating is relevant to the cooling flow problem (e.g.…”

Section: Introductionmentioning

confidence: 99%

Chemical enrichment of the intracluster medium by FR II radio sources

Heath¹,

Krause²,

Alexander³

2007

Monthly Notices of the Royal Astronomical Society

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D. Heath, M. Krause, and P. Alexander, 'Chemical enrichment of the intracluster medium by FR II radio sources', Monthly Notices of the Royal Astronomical Society, Vol. 374, pp. 787-792, December 2006, the version of record is available online at doi: 10.1111/j.1365-2966.2006.11191.xWe present 2D axisymmetric hydrodynamic simulations investigating the long-term effect of Fanaroff-Riley type II radio galaxies on the metal distribution of the surrounding intracluster medium (ICM). A light jet is injected into a cooling flow atmosphere for 10-30 Myr. We then follow the subsequent evolution for 3 Gyr on a spherical grid spanning 3 Mpc in radius. A series of passive tracer particles were placed in an annulus about the cluster core to simulate metal carrying clouds in order to calculate the metallicity (Z) as a function of time and radial distance from the cluster centre. The jet has a significant effect on the ICM over the entire 3-Gyr period. By the end of the simulations, the jets produced metallicities of ~10 per cent of the initial metallicity of the cluster core throughout much of the cluster. The jets transport the metals not only in mixing regions, but also through upweilling ICM behind the jet, enriching the cluster over both long and short distances

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Rüstungskontrolle

Cited by 32 publications

References 5 publications

Jet-induced star formation in gas-rich galaxies

Jet-induced star formation in gas-rich galaxies

The Central Parsecs of Centaurus A: High‐excitation Gas, a Molecular Disk, and the Mass of the Black Hole

Chemical enrichment of the intracluster medium by FR II radio sources

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