scholarly journals Mechanical heating by active galaxies

2005 ◽  
Vol 363 (1828) ◽  
pp. 655-665 ◽  
Author(s):  
Mitchell C. Begelman ◽  
Mateusz Ruszkowski
Keyword(s):  
Active Galactic Nuclei ◽  
Excess Entropy ◽  
Galactic Nuclei ◽  
Active Galaxies ◽  
Clusters Of Galaxies ◽  
Heating Mechanism ◽  
Central Regions ◽  
Radiative Losses ◽  
Analytic Models

Jets and winds are significant channels for energy loss from accreting black holes. These outflows mechanically heat their surroundings, through shocks as well as gentler forms of heating. We discuss recent efforts to understand the nature and distribution of mechanical heating by central active galactic nuclei (AGN) in clusters of galaxies, using numerical simulations and analytic models. Specifically, we will discuss whether the relatively gentle ‘effervescent heating’ mechanism can compensate for radiative losses in the central regions of clusters, and account for the excess entropy observed at larger radii. J. Binney (2005 Phil. Trans. R. Soc. A , 363 , 739−749, doi: 10.1098/rsta.2004.1520) discusses the possible role of violent, episodic heating by AGN in clusters.

scholarly journals Relativistic Iron Kα Emission in Seyfert Galaxies

1997 ◽  
Vol 159 ◽  
pp. 36-39
Author(s):  
K. Nandra
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Relativistic Effects ◽  
Seyfert Galaxies ◽  
Active Galaxies ◽  
Line Profiles ◽  
Central Black Hole ◽  
Gaussian Profile ◽  
Central Regions ◽  
Excellent Description

AbstractEvidence is presented for widespread relativistic effects in the central regions of active galactic nuclei (AGN). A sample of 18 Seyfert 1 galaxies observed by ASCA show iron Kα emission which is resolved, with mean full width at half maximum (FWHM) ~ 50,000 km s−1 for a Gaussian profile. However, many of the line profiles are asymmetric. A strong red wing is indicative of gravitational redshifts close to a central black hole, and accretion-disk models provide an excellent description of the data. Such observations probe the innermost regions of AGN, and arguably provide the best evidence yet obtained for the existence of supermassive black holes in the centers of active galaxies.

scholarly journals Induced Starburst and Nuclear Activity: Faith, Facts and Theory

1990 ◽  
Vol 124 ◽  
pp. 689-704 ◽  
Author(s):  
Isaac Shlosman
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Host Galaxies ◽  
Galactic Disks ◽  
Nuclear Activity ◽  
Gravitational Instabilities ◽  
Physical Understanding ◽  
Central Regions ◽  
Axisymmetric Perturbations

AbstractThe problem of the origin of starburst and nuclear (nonstellar) activity in galaxies is reviewed. A physical understanding of mechanism(s) that induce both types of activity requires one to address the following issues: 1) what is the source of fuel that powers starbursts and active galactic nuclei? and 2) how it is channeled towards the central regions of host galaxies? As a possible clue, we examine the role of non-axisymmetric perturbations of galactic disks and analyze their potential triggers. Global gravitational instabilities in the gas on scales ~ 100 pc appear to be crucial for fueling the active galactic nuclei.

scholarly journals Wolf-Rayet stars in Active Galactic Nuclei

1999 ◽  
Vol 193 ◽  
pp. 760-761
Author(s):  
Robin J.R. Williams ◽  
John E. Dyson ◽  
Judith J. Perry
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Active Galaxies ◽  
Emission Lines ◽  
Supply Rate ◽  
Stellar Cluster ◽  
Uv Emission ◽  
Ram Pressure

Starbursts, black holes and AGN have strong observational links, as discussed elsewhere in these proceedings. Perry & Dyson (1985 (PD), see also Perry 1994) studied the role of shocks around supernovae and stellar wind bubbles in the nuclei of active galaxies. Both the ejecta and the ambient ISM are initially shocked to high temperatures. PD found that while the shocked gas is maintained at high pressure by ram pressure, it cools rapidly, to then produce the observed optical and UV emission lines. The mass supply rate from the nuclear starburst, inferred from the strength of the emission lines, tallies well with that required by an accreting black hole to generate the observed luminosity. A symbiosis between a starburst stellar cluster and an accreting black hole naturally generates the observational features associated with QSOs.

scholarly journals Hot gaseous atmospheres of rotating galaxies observed with XMM–Newton

2020 ◽  
Vol 499 (4) ◽  
pp. 5163-5174
Author(s):  
A Juráňová ◽  
N Werner ◽  
P E J Nulsen ◽  
M Gaspari ◽  
K Lakhchaura ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Active Galactic Nuclei ◽  
Spiral Galaxy ◽  
Galactic Nuclei ◽  
X Ray ◽  
Hot Gas ◽  
Heating And Cooling ◽  
Theoretical Predictions ◽  
Central Regions ◽  
Gaseous Atmospheres

ABSTRACT X-ray emitting atmospheres of non-rotating early-type galaxies and their connection to central active galactic nuclei have been thoroughly studied over the years. However, in systems with significant angular momentum, processes of heating and cooling are likely to proceed differently. We present an analysis of the hot atmospheres of six lenticulars and a spiral galaxy to study the effects of angular momentum on the hot gas properties. We find an alignment between the hot gas and the stellar distribution, with the ellipticity of the X-ray emission generally lower than that of the optical stellar emission, consistent with theoretical predictions for rotationally supported hot atmospheres. The entropy profiles of NGC 4382 and the massive spiral galaxy NGC 1961 are significantly shallower than the entropy distribution in other galaxies, suggesting the presence of strong heating (via outflows or compressional) in the central regions of these systems. Finally, we investigate the thermal (in)stability of the hot atmospheres via criteria such as the TI- and C-ratio, and discuss the possibility that the discs of cold gas present in these objects have condensed out of the hot atmospheres.

scholarly journals Understanding the origin of radio outflows in Seyfert galaxies using radio polarimetry

2019 ◽  
Vol 15 (S356) ◽  
pp. 247-251
Author(s):  
Biny Sebastian ◽  
Preeti Kharb ◽  
Christopher P. O’ Dea ◽  
Jack F. Gallimore ◽  
Stefi A. Baum ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Radio Emission ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Seyfert Galaxy ◽  
Seyfert Galaxies ◽  
Starburst Galaxies ◽  
Galactic Magnetic Fields ◽  
5 Ghz

AbstractThe role of starburst winds versus active galactic nuclei (AGN) jets/winds in the formation of the kiloparsec scale radio emission seen in Seyferts is not yet well understood. In order to be able to disentangle the role of various components, we have observed a sample of Seyfert galaxies exhibiting kpc-scale radio emission suggesting outflows, along with a comparison sample of starburst galaxies, with the EVLA B-array in polarimetric mode at 1.4 GHz and 5 GHz. The Seyfert galaxy NGC 2639, shows highly polarized secondary radio lobes, not observed before, which are aligned perpendicular to the known pair of radio lobes. The additional pair of lobes represent an older epoch of emission. A multi-epoch multi-frequency study of the starburst-Seyfert composite galaxy NGC 3079, reveals that the jet together with the starburst superwind and the galactic magnetic fields might be responsible for the well-known 8-shaped radio lobes observed in this galaxy. We find that many of the Seyfert galaxies in our sample show bubble-shaped lobes, which are absent in the starburst galaxies that do not host an AGN.

scholarly journals The Role of Active Galactic Nuclei in the Quenching of Massive Galaxies in the SQuIGG$\vec{L}$E Survey

2020 ◽  
Vol 899 (1) ◽  
pp. L9
Author(s):  
Jenny E. Greene ◽  
David Setton ◽  
Rachel Bezanson ◽  
Katherine A. Suess ◽  
Mariska Kriek ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Massive Galaxies

Commission N°48: High Energy Astrophysics (Astrophysique Des Hautes Energies)

1988 ◽  
Vol 20 (1) ◽  
pp. 671-675
Author(s):  
C.J. Cesarsky ◽  
R.A. Sunyaev ◽  
G.W. Clark ◽  
R. Giacconi ◽  
Vin-Yue Qu ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Supernova Remnants ◽  
Cataclysmic Variables ◽  
Galactic Nuclei ◽  
High Energy ◽  
Clusters Of Galaxies ◽  
High Energy Astrophysics ◽  
X Ray ◽  
X Ray Binaries ◽  
Imaging Telescopes

The european X-ray observatory (EXOSAT), which was launched in 1983 and which finished operations in April 1986, has brought a rich harvest of results in the period 1984-1987, surveyed here. The EXOSAT payload consisted of three sets of instruments: two low energy imaging telescopes (LE:E<2 KeV), a medium-energy experiment (ME:E=l-50KeV) and a gas scintillation proportional counter (GSPC:E=2-20KeV). Over most of the energy range covered, EXOSAT was not more sensitive than its predecessor, the american EINSTEIN satellite. But the EINSTEIN satellite is far from having exhausted the treasures of the X-ray sky. And EXOSAT, thanks to its elliptical 90-hour orbit, had the extra advantage of being able to make long, continuous observations of interesting objects, lasting up to 72 hours. Thus, EXOSAT was very well suited for variability studies, and many of its most important findings are in this area. EXOSAT observations sample a vide range of astrophysical sources: X-ray binaries, cataclysmic variables and active stars; supernova remnants and the interstellar medium; active galactic nuclei, and clusters of galaxies. Among the highlights, let us mention:

scholarly journals MAGNETIC FIELD EFFECTS NEAR THE LAUNCHING REGION OF ASTROPHYSICAL JETS

2010 ◽  
Vol 19 (06) ◽  
pp. 729-739 ◽  
Author(s):  
E. M. DE GOUVEIA DAL PINO ◽  
G. KOWAL ◽  
L. H. S. KADOWAKI ◽  
P. PIOVEZAN ◽  
A. LAZARIAN
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Magnetic Energy ◽  
Galactic Nuclei ◽  
Young Stellar Objects ◽  
Magnetic Field Effects ◽  
Astrophysical Jets ◽  
Stellar Objects ◽  
Fundamental Properties

One of the fundamental properties of astrophysical magnetic fields is their ability to change topology through reconnection and in doing so, to release magnetic energy, sometimes violently. In this work, we review recent results on the role of magnetic reconnection and associated heating and particle acceleration in jet/accretion disk systems, namely young stellar objects (YSOs), microquasars, and active galactic nuclei (AGNs).

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