Observational Properties of Jets in Active Galactic Nuclei

Giovannini, G.

doi:10.1023/b:astr.0000044647.04235.d4

Cited by 24 publications

(29 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…) is re-ejected back by the SMBH, as discussed above, driven mostly in the kinetic form of UFOs and relativistic jets. Such AGN outflows/jets propagate and percolate deeper into the meso-scale atmosphere and start to entrain progressively more IGrM, loading part of the surrounding gas mass and decreasing their velocity down to several 1000 km s −1 (e.g., Giovannini [272], Fiore et al [273]). The last missing tile of the self-regulated cycle is the macro AGN feedback depositiona strongly debated topic since the launch of Chandra and XMM-Newton telescopes, as their angular resolution is mostly limited to the macro scale (Figure 9, top-right inset).…”

Section: Agn Feedback and Heating Processesmentioning

confidence: 99%

Feedback from Active Galactic Nuclei in Galaxy Groups

et al. 2021

View full text Add to dashboard Cite

The co-evolution between supermassive black holes and their environment is most directly traced by the hot atmospheres of dark matter halos. The cooling of the hot atmosphere supplies the central regions with fresh gas, igniting active galactic nuclei (AGN) with long duty cycles. Outflows from the central engine tightly couple with the surrounding gaseous medium and provide the dominant heating source preventing runaway cooling by carving cavities and driving shocks across the medium. The AGN feedback loop is a key feature of all modern galaxy evolution models. Here, we review our knowledge of the AGN feedback process in the specific context of galaxy groups. Galaxy groups are uniquely suited to constrain the mechanisms governing the cooling–heating balance. Unlike in more massive halos, the energy that is supplied by the central AGN to the hot intragroup medium can exceed the gravitational binding energy of halo gas particles. We report on the state-of-the-art in observations of the feedback phenomenon and in theoretical models of the heating-cooling balance in galaxy groups. We also describe how our knowledge of the AGN feedback process impacts galaxy evolution models and large-scale baryon distributions. Finally, we discuss how new instrumentation will answer key open questions on the topic.

show abstract

Section: Agn Feedback and Heating Processesmentioning

confidence: 99%

Feedback from Active Galactic Nuclei in Galaxy Groups

et al. 2021

View full text Add to dashboard Cite

show abstract

“…In considering massive slow outflows, we are implicitly assuming that the relativistic jet entrains some ISM mass (the active mass M act , defined below) or perhaps that a wind originates from the accretion disc (Crenshaw, Kraemer & George 2003;Morganti et al 2007;Nesvadba et al 2008;Cappi et al 2009;Cappi, Giustini & Tombesi 2011;Tombesi et al 2010aTombesi et al ,b, 2012; see also the references in G11a,b). Moreover, radio jets are highly relativistic on a pc scale, but rapidly decrease to subrelativistic velocities within a few kpc from the black hole (Giovannini 2004).…”

Section: Self-regulated Mechanical Outflowsmentioning

confidence: 99%

Mechanical AGN feedback: controlling the thermodynamical evolution of elliptical galaxies

Gaspari

Brighenti

Temi

2012

Monthly Notices of the Royal Astronomical Society

170

179

View full text Add to dashboard Cite

A fundamental gap in the current understanding of galaxies concerns the thermodynamical evolution of ordinary, baryonic matter. On the one hand, radiative emission drastically decreases the thermal energy content of the interstellar plasma (ISM), inducing a slow cooling flow towards the centre. On the other hand, the active galactic nucleus (AGN) struggles to prevent the runaway cooling catastrophe, injecting huge amount of energy into the ISM. The present study intends to investigate thoroughly the role of mechanical AGN feedback in (isolated or massive) elliptical galaxies, extending and completing the mass range of tested cosmic environments. Our previously successful feedback models in galaxy clusters and groups demonstrated that AGN outflows, self‐regulated by cold gas accretion, are able to quench the cooling flow properly without destroying the cool core. Via three‐dimensional hydrodynamic simulations (flash 3.3), also including stellar evolution, we show that massive mechanical AGN outflows can indeed solve the cooling‐flow problem for the entire life of the galaxy, at the same time reproducing typical observational features and constraints such as buoyant underdense bubbles, elliptical shock cocoons, sonic ripples, dredge‐up of metals, subsonic turbulence and extended filamentary or nuclear cold gas. In order to avoid overheating and totally emptying the isolated galaxy, the frequent mechanical AGN feedback should be less powerful and efficient (ε∼ 10−4) compared with the heating required for more massive and bound ellipticals surrounded by the intragroup medium (ε∼ 10−3).

show abstract

“…On a much larger scale, relativistic radio jets are accelerated in the innermost cores of active galactic nuclei (AGN) (e.g. Giovannini 2004): their emitting component is synchrotron relativistic electrons, with a cold proton component or, most likely, a Poynting flux electromagnetic component (De Young 2006). Despite being characterized by extremely different space, time, and energy scales, it is commonly accepted that all these systems derive their energy from accretion onto a central object (Livio 1999), and the physical origin of these supersonic outflows has been related to the dynamical evolution of magnetized accretion disks around a deep gravitational well.…”

Section: Introductionmentioning

confidence: 99%

MHD simulations of jet acceleration from Keplerian accretion disks

Zanni¹,

Ferrari²,

Rosner³

et al. 2007

A&A

207

244

View full text Add to dashboard Cite

Context. Accretion disks and astrophysical jets are used to model many active astrophysical objects, such as young stars, relativistic stars, and active galactic nuclei. However, existing proposals for how these structures may transfer angular momentum and energy from disks to jets through viscous or magnetic torques do not yet provide a full understanding of the physical mechanisms involved. Thus, global stationary solutions have not explained the stability of these structures; and global numerical simulations that include both the disk and jet physics have so far been limited to relatively short time scales and narrow (and possibly astrophysically unlikely) ranges of viscosity and resistivity parameters that may be crucial to defining the coupling of the inflow-outflow dynamics. Aims. We present self-consistent, time-dependent simulations of supersonic jets launched from magnetized accretion disks, using high-resolution numerical techniques. In particular we study the effects of the disk's magnetic resistivity, parametrized through an α-prescription, in determining the properties of the inflow-outflow system. Moreover we analyze under which conditions steady state solutions of the type proposed in the self-similar models of Blandford & Payne can be reached and maintained in a self-consistent nonlinear stage. Methods. We used the resistive MHD FLASH code with adaptive mesh refinement (AMR), allowing us to follow the evolution of the structure on a long enough time scale to reach steady state. A detailed analysis of the initial configuration state is given. Results. We obtain the expected solutions within the axisymmetric (2.5 D) limit. Assuming a magnetic field around equipartition with the thermal pressure of the disk, we show how the characteristics of the disk-jet system, such as the ejection efficiency and the energetics, are affected by the anomalous resistivity acting inside the disk.

show abstract

Observational Properties of Jets in Active Galactic Nuclei

Cited by 24 publications

References 21 publications

Feedback from Active Galactic Nuclei in Galaxy Groups

Feedback from Active Galactic Nuclei in Galaxy Groups

Mechanical AGN feedback: controlling the thermodynamical evolution of elliptical galaxies

MHD simulations of jet acceleration from Keplerian accretion disks

Contact Info

Product

Resources

About