An analytical model for spherical galaxies and bulges

Hernquist, Lars

doi:10.1086/168845

Cited by 2,886 publications

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“…The SE filament may have a similar velocity gradient obscured by an orientation close to the line of sight. Table 1. galaxy, expressed in terms of the total mass and effective radius, that reproduces a de Vaucouleurs surface brightness profile (Hernquist 1990). The velocity of a gas blob that free-falls in this potential is given by…”

Section: Molecular Gas Clouds In Gravitational Free-fall?mentioning

confidence: 99%

ALMA observations of cold molecular gas filaments trailing rising radio bubbles in PKS 0745−191

Russell

McNamara

Fabian

et al. 2016

Mon. Not. R. Astron. Soc.

105

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We present ALMA observations of the CO(1-0) and CO(3-2) line emission tracing filaments of cold molecular gas in the central galaxy of the cluster PKS 0745-191. The total molecular gas mass of 4.6±0.3×10 9 M , assuming a Galactic X CO factor, is divided roughly equally between three filaments each extending radially 3 − 5 kpc from the galaxy centre. The emission peak is located in the SE filament ∼ 1 arcsec (2 kpc) from the nucleus. The velocities of the molecular clouds in the filaments are low, lying within ±100 km s −1 of the galaxy's systemic velocity. Their FWHMs are less than 150 km s −1 , which is significantly below the stellar velocity dispersion. Although the molecular mass of each filament is comparable to a rich spiral galaxy, such low velocities show that the filaments are transient and the clouds would disperse on < 10 7 yr timescales unless supported, likely by the indirect effect of magnetic fields. The velocity structure is inconsistent with a merger origin or gravitational free-fall of cooling gas in this massive central galaxy. If the molecular clouds originated in gas cooling even a few kpc from their current locations their velocities would exceed those observed. Instead, the projection of the N and SE filaments underneath X-ray cavities suggests they formed in the updraft behind bubbles buoyantly rising through the cluster atmosphere. Direct uplift of the dense gas by the radio bubbles appears to require an implausibly high coupling efficiency. The filaments are coincident with low temperature X-ray gas, bright optical line emission and dust lanes indicating that the molecular gas could have formed from lifted warmer gas that cooled in situ.

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Section: Molecular Gas Clouds In Gravitational Free-fall?mentioning

confidence: 99%

ALMA observations of cold molecular gas filaments trailing rising radio bubbles in PKS 0745−191

Russell

McNamara

Fabian

et al. 2016

Mon. Not. R. Astron. Soc.

105

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“…Thus, the (M/L) D I S K as well as the dark matter (DM) halo properties -central density ρ 0 and core radius r 0 , are free parameters. The DM halo can be either a pseudo-isothermal sphere (Begeman 1987), a NFW profile (Navarro et al 1996), or a Hernquist (1990) profile.…”

Section: Observations and Main Kinematical Resultsmentioning

confidence: 99%

Numerical Simulations of KPG 302 (NGC 3893/96)

Rosado¹,

Gabbasov²,

Fuentes-Carrera³

2010

Proc. IAU

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Abstract. We present the results of numerical simulations on the M51-type galaxy pair KPG 302 (NGC 3893/96) taking as boundary conditions for these simulations the results of our observations on the kinematics of this pair. The observations allow us to deduce the different components of each galaxy in the pair (stellar disk and bulge, dark matter halo) as well as the geometry of the encounter at the present time. The numerical simulations were carried out using GADGET2 numerical code including gas. We describe in detail how the numerical simulations are being done. We succeeded to reproduce the actual conditions of the pair, in particular, the granddesign spiral arms of NGC 3893 (the main galaxy of the pair) when the numerical simulations include gas, consider a parabolic direct collision and multiple passages.

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“…Formula (1), known as generalised isochrones potential formula, was proposed in 1973 (Kuzmin et al (1973, p. 301)). Its special case was rediscovered in 1990 (Hernquist (1990)) so that it has often been cited as the Hernquist formula. The density expression corresponding to (1) in the special case r b → 0 is…”

Section: Density and Potential Formulaementioning

confidence: 99%

Mass Distribution and Gravitational Potential of the Milky Way

Ninković

2017

Open Astronomy

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Models of mass distribution in the Milky Way are discussed where those yielding the potential analytically are preferred. It is noted that there are three main contributors to the Milky Way potential: bulge, disc and dark halo. In the case of the disc the Miyamoto-Nagai formula, as simple enough, has shown as a very good solution, but it has not been able to satisfy all requirements. Therefore, improvements, such as adding new terms or combining several Miyamoto-Nagai terms, have been attempted. Unlike the disc, in studying the bulge and dark halo the flattening is usually neglected, which offers the possibility of obtaining an exact solution of the Poisson equation. It is emphasized that the Hernquist formula, used very often for the bulge potential, is a special case of another formula and the properties of that formula are analysed. In the case of the dark halo, the slopes of its cumulative mass for the inner and outer parts are explained through a new formalism presented here for the first time.

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An analytical model for spherical galaxies and bulges

Cited by 2,886 publications

References 0 publications

ALMA observations of cold molecular gas filaments trailing rising radio bubbles in PKS 0745−191

ALMA observations of cold molecular gas filaments trailing rising radio bubbles in PKS 0745−191

Numerical Simulations of KPG 302 (NGC 3893/96)

Mass Distribution and Gravitational Potential of the Milky Way

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