Theoretical determination of H i vertical scale heights in the dwarf galaxies DDO 154, Ho II, IC 2574 and NGC 2366

Banerjee, Arunima; Jog, Chanda J.; Brinks, E.; Bagetakos, Ioannis

doi:10.1111/j.1365-2966.2011.18745.x

Cited by 53 publications

(61 citation statements)

References 43 publications

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“…It would be interesting to see if this holds in MOND for which the disc, by definition, must be maximal. Banerjee et al (2011) made an analysis of the scale-heights of the gas-dominated THINGS galaxies in Newtonian gravity and it is essential that a similar review is made of the same galaxies in MOND. Figure 11.…”

Section: Stellar Scale-heightsmentioning

confidence: 99%

A QUMOND galactic N-body code - I. Poisson solver and rotation curve fitting

Angus

Heyden

Famaey

et al. 2012

Monthly Notices of the Royal Astronomical Society

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Here we present a new particle‐mesh galactic N‐body code that uses the full multigrid algorithm for solving the modified Poisson equation of the quasi‐linear formulation of modified Newtonian dynamics (QUMOND). A novel approach for handling the boundary conditions using a refinement strategy is implemented and the accuracy of the code is compared with analytical solutions of Kuzmin discs. We then employ the code to compute the predicted rotation curves for a sample of five spiral galaxies from the THINGS sample. We generated static N‐body realizations of the galaxies according to their stellar and gaseous surface densities and allowed their distances, mass‐to‐light ratios (M/L values) and both the stellar and gas scale‐heights to vary in order to estimate the best‐fitting parameters. We found that NGC 3621, NGC 3521 and DDO 154 are well fitted by MOND using expected values of the distance and M/L. NGC 2403 required a moderately larger M/L than expected and NGC 2903 required a substantially larger value. The surprising result was that the scale‐height of the dominant baryonic component was well constrained by the rotation curves: the gas scale‐height for DDO 154 and the stellar scale‐height for the others. In fact, if the suggested stellar scale‐height (one‐fifth the stellar scale‐length) was used in the case of NGC 3621 and NGC 3521 it would not be possible to produce a good fit to the inner rotation curve. For each of the four stellar dominated galaxies, we calculated the vertical velocity dispersions which we found to be, on the whole, quite typical compared with observed stellar vertical velocity dispersions of face‐on spirals. We conclude that modelling the gas scale‐heights of the gas‐rich dwarf spiral galaxies will be vital in order to make precise conclusions about MOND.

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Section: Stellar Scale-heightsmentioning

confidence: 99%

A QUMOND galactic N-body code - I. Poisson solver and rotation curve fitting

Angus

Heyden

Famaey

et al. 2012

Monthly Notices of the Royal Astronomical Society

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“…Banerjee et al (2011) studied the flaring of the gas layer in four of the THINGS dwarf galaxies, again using the hydrostatic equilibrium approach. For DDO 154, the disk flares to ∼1 kpc at a radius of ∼5 kpc.…”

Section: Velocity Dispersions In Dwarf Irregular Galaxiesmentioning

confidence: 99%

Hi in the Outskirts of Nearby Galaxies

Bosma

2017

Astrophysics and Space Science Library

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The HI in disk galaxies frequently extends beyond the optical image, and can trace the dark matter there. I briefly highlight the history of high spatial resolution HI imaging, the contribution it made to the dark matter problem, and the current tension between several dynamical methods to break the disk-halo degeneracy. I then turn to the flaring problem, which could in principle probe the shape of the dark halo. Instead, however, a lot of attention is now devoted to understanding the role of gas accretion via galactic fountains. The current Λ cold dark matter theory has problems on galactic scales, such as the core-cusp problem, which can be addressed with HI observations of dwarf galaxies. For a similar range in rotation velocities, galaxies of type Sd have thin disks, while those of type Im are much thicker. After a few comments on modified Newtonian dynamics and on irregular galaxies, I close with statistics on the HI extent of galaxies.

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“…This task has been attempted only by very few authors (Narayan & Jog 2002;Harfst et al 2006;Banerjee et al 2011). The typical justification for neglecting gas self-gravity in constructing initial equilibrium models for DGs is that "the gravitational potential of DGs with M g < ∼ 10 9 M is dominated by the dark matter halo" (Mac Low & Ferrara 1999).…”

Section: Introductionmentioning

confidence: 99%

Self-gravitating equilibrium models of dwarf galaxies and the minimum mass for star formation

Vorobyov

Recchi

Hensler

2012

A&A

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Context. We constructed a series of model galaxies in rotational equilibrium consisting of gas, stars, and a fixed dark matter (DM) halo and studied how these equilibrium systems depend on the mass and form of the DM halo, gas temperature, non-thermal and rotation support against gravity, and also on the redshift of galaxy formation. For every model galaxy we found the minimum gas mass M min g required to achieve a state in which star formation (SF) is allowed according to contemporary SF criteria. The obtained M min g -M DM relations were compared against the baryon-to-DM mass relation M b -M DM inferred from the ΛCDM theory and WMAP4 data. Aims. Our aim is to construct realistic initial models of dwarf galaxies (DGs), which take into account the gas self-gravity and can be used as a basis to study the dynamical and chemical evolution of DGs. Methods. Rotating equilibria are found by solving numerically the steady-state momentum equation for the gas component in the combined gravitational potential of gas, stars, and DM halo using a forward substitution procedure. Results. We find that for a given M DM the value of M min g depends crucially on the gas temperature T g , gas spin parameter α, degree of non-thermal support σ eff , and somewhat on the redshift for galaxy formation z gf . Depending on the actual values of T g , α, σ eff , and z gf , model galaxies may have M M b , implying that they need much more gas than available to achieve a state in which SF is allowed. Conclusions. Our modeling suggests that a star-formation-allowed state is more difficult to achieve in DM halos with mass < ∼ 10 9 M than in their upper-mass counterparts, because the required gas mass often exceeds both M b and M DM . In the framework of the ΛCDM theory, this implies the existence of a critical DM halo mass below which the likelihood of star formation and hence the total stellar mass may drop substantially, in accordance with the stellar versus DM halo mass relations recently derived from the SDSS survey and millennium simulations. On the other hand, DGs that do not follow the ΛCDM trend are feasible and have recently been identified, which raises questions about the universality of the ΛCDM paradigm.

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Theoretical determination of H i vertical scale heights in the dwarf galaxies DDO 154, Ho II, IC 2574 and NGC 2366

Cited by 53 publications

References 43 publications

A QUMOND galactic N-body code - I. Poisson solver and rotation curve fitting

A QUMOND galactic N-body code - I. Poisson solver and rotation curve fitting

Hi in the Outskirts of Nearby Galaxies

Self-gravitating equilibrium models of dwarf galaxies and the minimum mass for star formation

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