Time evolution of galactic warps in prolate haloes

Ideta, Makoto; Hozumi, Shunsuke; Tsuchiya, Toshio; Takizawa, Motokazu

doi:10.1046/j.1365-8711.2000.03092.x

Cited by 30 publications

(37 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Also, there is some evidence in recent literature in favour of prolate-shaped halos. For example, Ideta et al (2000) find that prolate halo helps sustain warps better. Figure 2 shows that the scaleheight upto 16 kpc radius remains almost unaffected by the change in halo shape and the effect of shape is prominent only beyond 20 kpc.…”

Section: Shape Of the Halomentioning

confidence: 99%

Constraints on the halo density profile using HI flaring in the outer Galaxy

Narayan¹,

Saha²,

Jog³

2005

A&A

View full text Add to dashboard Cite

Abstract. The observed flaring of HI disk in the outer region of galaxies has been used in the past to determine the shape of the dark matter halo. Previous studies based on this concept suggest a slightly oblate halo (axis ratio ∼0.8) for our Galaxy. We reinvestigate this problem by calculating the HI scaleheight in the outer Galaxy to a larger radial distance, and by studying its dependence on the shape and the density profile of the halo. We find that a simple isothermal infinite halo of any shape-oblate or prolate, is not able to account for the observed flaring. Instead we show that a spherical halo with density falling faster than isothermal halo in the outer region provides a better fit to the observed HI flaring as well as the observed rotation curve of our Galaxy. These halos have about 95% of their mass within a few hundreds of kpc for R • = 8.5 kpc and Θ • = 220 km s −1 , the central density and core radius can be constrained to the range ρ • = 0.035−0.06 M pc −3 and R c = 8−10 kpc. Our claim for such "finite-sized" spherical halos is supported by recent literature on numerical simulation studies of halo formation as well as analyses of SDSS data.

show abstract

Section: Shape Of the Halomentioning

confidence: 99%

Constraints on the halo density profile using HI flaring in the outer Galaxy

Narayan¹,

Saha²,

Jog³

2005

A&A

View full text Add to dashboard Cite

show abstract

“…This model requires a halo that is much more massive than the disc, an extremely high accretion rate (3 disc masses in 0.9 Gyr; Jiang & Binney 1999) and, in this scenario, after a sufficiently long time, the angular momentum of the Galaxy to become parallel to the direction of the falling matter causing the warp to decay. It is difficult to understand why the warps are so frequent in this scenario but this difficulty might be overcome by including a prolate halo (Ideta et al 2000), which would prolong the warp's existence. Also, it is difficult to understand how a low-density halo can retain the accreted intergalactic matter.…”

Section: Introductionmentioning

confidence: 99%

Warps and correlations with intrinsic parameters of galaxies in the visible and radio

Castro-Rodríguez

López-Corredoira

Sánchez-Saavedra

et al. 2002

A&A

View full text Add to dashboard Cite

Abstract. From a comparison of the different parameters of warped galaxies in the radio, and especially in the visible, we find that: a) No large galaxy (large mass or radius) has been found to have high amplitude in the warp, and there is no correlation of size/mass with the degree of asymmetry of the warp. b) The disc density and the ratio of dark to luminous mass show an opposing trend: smaller values give more asymmetric warps in the inner radii (optical warps) but show no correlation with the amplitude of the warp; however, in the external radii is there no correlation with asymmetry. c) A third anticorrelation appears in a comparison of the amplitude and degree of asymmetry in the warped galaxies. Hence, it seems that very massive dark matter haloes have nothing to do with the formation of warps but only with the degree of symmetry in the inner radii, and are unrelated to the warp shape for the outermost radii. Denser discs show the same dependence.

show abstract

“…Cosmological simulations demonstrate that dark matter halos are inclined to be more frequently prolate than oblate (Dubinski & Carlberg 1991;Warren et al 1992). In addition, prolate halos can be supported from the standpoint of the longevity of galactic warps; Ideta et al (2000) have shown that a warped structure persists for a long time in a prolate halo, while it disappears quickly in an oblate halo.…”

mentioning

confidence: 99%

Bar Dissolution in Prolate Halos

Ideta

Hozumi

2000

The Astrophysical Journal

View full text Add to dashboard Cite

The time evolution of barred structures is examined under the influence of the external forces exerted by a spherical halo and by prolate halos. In particular, galaxy disks are placed in the plane including the major axis of prolate halos, whose configuration is often found in cosmological simulations. N-body disks in fixed external halo fields are simulated, so that bars are formed via dynamical instability. In the subsequent evolution, the bars in prolate halos dissolve gradually with time, while the bar pattern in a spherical halo remains almost unchanged to the end of the simulation. The decay times of the bars suggest that they can be destroyed in a time smaller than a Hubble time. Our results indicate that this dissolution process could occur in real barred galaxies, if they are surrounded by massive dark prolate halos, and the configuration adopted here is not unusual from the viewpoint of galaxy formation. For a prolate halo model, an additional simulation that is restricted to two-dimensional inplane motions has also ended up with similar bar dissolution. This means that the vertical motions of disk stars do not play an essential role in the bar dissolution demonstrated here.

show abstract

Time evolution of galactic warps in prolate haloes

Cited by 30 publications

References 28 publications

Constraints on the halo density profile using HI flaring in the outer Galaxy

Constraints on the halo density profile using HI flaring in the outer Galaxy

Warps and correlations with intrinsic parameters of galaxies in the visible and radio

Bar Dissolution in Prolate Halos

Contact Info

Product

Resources

About