NGC 4138: A Case Study in Counterrotating Disk Formation

Thakar, Aniruddha R.; Ryden, Barbara S.; Jore, Katherine P.; Broeils, A. H.

doi:10.1086/303915

Cited by 52 publications

(58 citation statements)

References 39 publications

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“…Thus the jet has to be fed from incoming particles with retrograde orbits in the accretion disk. There is evidence for the existence of substantial counterrotating parts of accretion disks (Koide et al 2000;Thakar et al 1997), and such counterrotations could explain the viscosity inducing the instabilities which trigger the falling of matter towards the ergosphere. It is now known (Mirabel & Rodriguez 1994, 1999Mirabel 2006) that there is a close connection between instabilities in the accretion disk and the genesis of jets for quasars and microquasars.…”

Section: Resultsmentioning

confidence: 99%

Kerr geodesics, the Penrose process and jet collimation by a black hole

Gariel

MacCallum²,

Marcilhacy

et al. 2010

A&A

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Aims. We re-examine the possibility that astrophysical jet collimation may arise from the geometry of rotating black holes and the presence of high-energy particles resulting from a Penrose process, without the help of magnetic fields. Methods. Our analysis uses the Weyl coordinates, which are revealed better adapted to the desired shape of the jets. We numerically integrate the 2D-geodesics equations. Results. We give a detailed study of these geodesics and give several numerical examples. Among them are a set of perfectly collimated geodesics with asymptotes ρ = ρ 1 parallel to the z-axis, with ρ 1 only depending on the ratios, where a and M are the parameters of the Kerr black hole, E the particle energy and Q the Carter's constant.

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Section: Resultsmentioning

confidence: 99%

Kerr geodesics, the Penrose process and jet collimation by a black hole

Gariel

MacCallum²,

Marcilhacy

et al. 2010

A&A

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“…This leaves us with the possibility of the acquisition of small gas clouds coming either from the environment or from the internal reservoir inside the galaxy itself. When external gas is captured in distinct clouds, it settles onto the galaxy disk in a relatively short time (∼ 1 Gyr, Thakar et al 1997;Algorry et al 2014;Mapelli et al 2015). In this case, NGC 1366 could be an object caught at an intermediate stage of the acquisition process, before its configuration becomes stable.…”

Section: Discussionmentioning

confidence: 99%

Kinematic and stellar population properties of the counter-rotating components in the S0 galaxy NGC 1366

Morelli

Pizzella

Coccato

et al. 2017

A&A

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Context. Many disk galaxies host two extended stellar components that rotate in opposite directions. The analysis of the stellar populations of the counter-rotating components provides constraints on the environmental and internal processes that drive their formation. Aims. The S0 NGC 1366 in the Fornax cluster is known to host a stellar component that is kinematically decoupled from the main body of the galaxy. Here we successfully separated the two counter-rotating stellar components to independently measure the kinematics and properties of their stellar populations. Methods. We performed a spectroscopic decomposition of the spectrum obtained along the galaxy major axis and separated the relative contribution of the two counter-rotating stellar components and of the ionized-gas component. We measured the line-strength indices of the two counter-rotating stellar components and modeled each of them with single stellar population models that account for the α/Fe overabundance. Results. We found that the counter-rotating stellar component is younger, has nearly the same metallicity, and is less α/Fe enhanced than the corotating component. Unlike most of the counter-rotating galaxies, the ionized gas detected in NGC 1366 is neither associated with the counter-rotating stellar component nor with the main galaxy body. On the contrary, it has a disordered distribution and a disturbed kinematics with multiple velocity components observed along the minor axis of the galaxy. Conclusions. The different properties of the counter-rotating stellar components and the kinematic peculiarities of the ionized gas suggest that NGC 1366 is at an intermediate stage of the acquisition process, building the counter-rotating components with some gas clouds still falling onto the galaxy.

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“…These in turn have now proliferated, and it seems likely that both of the main contenders, sudden acquisition of a small galaxy coming out of left field or gradual infall of contrary-minded gas, will work (Thakar et al 1997). Both can also trigger starbursts (Coziol et al 1997).…”

Section: A Few Things That Go Backwardmentioning

confidence: 99%

Astrophysics in 1997

Trimble¹,

McFadden²

1998

PUBL ASTRON SOC PAC

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ABSTRACT. Martian marvels, a gamma-ray burster with a redshift, Galileo converses with Ganymede, a record galactic redshift of 4.92, and much else. Fiscal 1997 was definitely an exciting year for astronomers. We have tried hard to hit all the obvious highlights, but also to report more gradual progress on traditional problems of understanding planets, stars, galaxies, and the universe. Though the year was saddened by the loss of many valued colleagues, we nevertheless indulge in occasional soupçons of frivolity.

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NGC 4138: A Case Study in Counterrotating Disk Formation

Cited by 52 publications

References 39 publications

Kerr geodesics, the Penrose process and jet collimation by a black hole

Kerr geodesics, the Penrose process and jet collimation by a black hole

Kinematic and stellar population properties of the counter-rotating components in the S0 galaxy NGC 1366

Astrophysics in 1997

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