Effects of gas on the global stability of galactic disks - Radial flows

Shlosman, Isaac; Noguchi, Masafumi

doi:10.1086/173094

Cited by 126 publications

(134 citation statements)

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“…Although the sticky particle model has sucMuller ceeded in addressing some important aspects of hydrodynamical interaction in the interstellar medium, such as dynamical interaction between giant molecular clouds (e.g., Roberts & Hausman 1984 ;Combes & Gerin 1985), its weak point is considered to be an ad hoc estimate of an energy dissipation in cloud collisions (e.g., Shlosman & Noguchi 1993). On the other hand, the SPH method, which often introduces a virtual cuto † of the cooling function around 104 K (e.g., Katz 1992) and thus can investigate only warm gas components (T [ 103È104 K), cannot follow formation and evolution of cold molecular components that may well dominate the interstellar medium in very gas-rich young disk galaxies.…”

Section: Methodsmentioning

confidence: 99%

Formation of the Galactic Stellar Halo. I. Structure and Kinematics

Bekki¹

2001

ApJ

100

121

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We perform numerical simulations for the formation of the Galactic stellar halo, based on the currently favored cold dark matter theory of galaxy formation. Our numerical models, taking into account both dynamical and chemical evolution processes in a consistent manner, are aimed at explaining the observed structure and kinematics of the stellar halo in the context of hierarchical galaxy formation. The main results of the present simulations are summarized as follows : (1) Basic physical processes involved in the formation of the stellar halo, composed of metal-deÐcient stars with [Fe/H] ¹ [1.0, are described by both dissipative and dissipationless merging of subgalactic clumps and their resultant tidal disruption in the course of gravitational contraction of the Galaxy at high redshift (z [ 1). (2) The simulated halo has a density proÐle similar to the observed power-law form of o(r) D r~3.5 and also has a metallicity distribution similar to the observations. The halo shows virtually no radial gradient for stellar ages and only a small gradient for metallicities. (3) The dual nature of the halo, i.e., its inner Ñattened and outer spherical density distribution, is reproduced, at least qualitatively, by the present model. The outer spherical halo is formed via essentially dissipationless merging of small subgalactic clumps, whereas the inner Ñattened one is formed via three di †erent mechanisms, i.e., dissipative merging between larger, more massive clumps, adiabatic contraction due to the growing Galactic disk, and gaseous accretion onto the equatorial plane. Based on these results, we discuss how early pro-SV Õ T. cesses of dissipationless and dissipative merging of subgalactic clumps can reproduce plausibly and consistently the recent observational results on the Galactic stellar halo. We also present a possible scenario for the formation of the entire Galaxy structure, including bulge and disk components, in conjunction with halo formation.

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Section: Methodsmentioning

confidence: 99%

Formation of the Galactic Stellar Halo. I. Structure and Kinematics

Bekki¹

2001

ApJ

100

121

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“…Several physical mechanisms can cause a fraction of the gas in galaxies to lose angular momentum and to pile up in the very central regions. A non exhaustive list includes gas drag, dynamical friction of gas plus star clumps, tidal fields, spiral waves, winds and bars, radiation drag (e.g., Norman & Scoville 1988;Shlosman et al 1989Shlosman et al , 1990Shlosman & Noguchi 1993;Hernquist & Mihos 1995;Noguchi 1999;Umemura 2001;Kawakatu & Umemura 2002;Kawakatu et al 2003;Thompson et al 2005;Bournaud et al 2007Bournaud et al , 2011, 2011. In general the presence of clumps, which may be generated by fragmentation of gas already organized in an unstable disc or by inflow of gas and star subclumps, tends to increase the efficiency of such mechanisms.…”

Section: The Reservoirmentioning

confidence: 99%

The Coevolution of Supermassive Black Holes and Massive Galaxies at High Redshift

Lapi

Raimundo

Aversa

et al. 2014

ApJ

114

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We exploit the recent, wide samples of far-infrared (FIR) selected galaxies followed-up in X rays and of X-ray/optically selected active galactic nuclei (AGNs) followed-up in the FIR band, along with the classic data on AGN and stellar luminosity functions at high redshift z 1.5, to probe different stages in the coevolution of supermassive black holes (BHs) and host galaxies. The results of our analysis indicate the following scenario: (i) the star formation in the host galaxy proceeds within a heavily dust-enshrouded medium at an almost constant rate over a timescale 0.5 − 1 Gyr, and then abruptly declines due to quasar feedback; over the same timescale, (ii) part of the interstellar medium loses angular momentum, reaches the circum-nuclear regions at a rate proportional to the star formation and is temporarily stored into a massive reservoir/proto-torus wherefrom it can be promptly accreted; (iii) the BH grows by accretion in a self-regulated regime with radiative power that can slightly exceed the Eddington limit L/L Edd 4, particularly at the highest redshifts; (iv) for massive BHs the ensuing energy feedback at its maximum exceeds the stellar one and removes the interstellar gas, thus stopping the star formation and the fueling of the reservoir; (v) afterwards, if the latter has retained enough gas, a phase of supply-limited accretion follows exponentially declining with a timescale of about 2 e-folding times. We also discuss how the detailed properties and the specific evolution of the reservoir can be investigated via coordinated, high-resolution observations of starforming, strongly-lensed galaxies in the (sub-)mm band with ALMA and in the X-ray band with Chandra and the next generation X-ray instruments.

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“…-Large amounts of gas will destroy any triaxiality (Shlosman & Noguchi 1993). -A high stellar velocity dispersion.…”

Section: Introductionmentioning

confidence: 99%

Dark and luminous matter in the NGC 3992 group of galaxies

Bottema¹,

Verheijen²

2002

A&A

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Abstract. Detailed neutral hydrogen observations have been obtained of the large barred spiral galaxy NGC 3992 and its three small companion galaxies, UGC 6923, UGC 6940, and UGC 6969. For the main galaxy, the H i distribution is regular with a low level radial extension outside the stellar disc. However, at exactly the region of the bar, there is a pronounced central H i hole in the gas distribution. Likely gas has been transported inwards by the bar and because of the emptyness of the hole no large accretion events can have happened in recent galactic times. The gas kinematics is very regular and it is demonstrated that the influence of the bar potential on the velocity field is negligible. A precise and extended rotation curve has been derived showing some distinct features which can be explained by the non-exponential radial light distribution of NGC 3992. The decomposition of the rotation curve gives a slight preference for a sub maximal disc, though a range of disc contributions, up to a maximum disc situation fits nearly equally well. For such a maximum disc contribution, which might be expected in order to generate and maintain the bar, the required mass-to-light ratio is large but not exceptional.

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Effects of gas on the global stability of galactic disks - Radial flows

Cited by 126 publications

References 0 publications

Formation of the Galactic Stellar Halo. I. Structure and Kinematics

Formation of the Galactic Stellar Halo. I. Structure and Kinematics

The Coevolution of Supermassive Black Holes and Massive Galaxies at High Redshift

Dark and luminous matter in the NGC 3992 group of galaxies

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