Dynamical Centers and Noncircular Motions in Things Galaxies: Implications for Dark Matter Halos

Trachternach, C.; Blok, W. J. G. de; Walter, Fabian; Brinks, E.; Kennicutt, Robert C.

doi:10.1088/0004-6256/136/6/2720

Cited by 136 publications

(171 citation statements)

References 45 publications

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“…They find that that the ellipticity of the potential in the plane of the disk is most likely between 0 and ∼0.06. This is in good agreement with what Trachternach et al (2008) found observationally for a sample of 18 dwarf and spiral galaxies from the THINGS survey de Blok et al 2008), but in disagreement with results from CDM simulations which predict more elongated potentials (e.g., Frenk et al 1988;Hayashi & Navarro 2006). The smaller scatter in the observed BTF relation (e.g., McGaugh 2005), means that it can be used to put similar constraints on lower mass galaxies as well.…”

Section: Introductionsupporting

confidence: 80%

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The baryonic Tully-Fisher relation and its implication for dark matter halos

Trachternach

Blok²,

McGaugh

et al. 2009

A&A

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Context. The baryonic Tully-Fisher relation (BTF) is a fundamental relation between baryonic mass and maximum rotation velocity. It can be used to estimate distances, as well as to constrain the properties of dark matter and its relation with the visible matter. Aims. In this paper, we explore if extremely low-mass dwarf galaxies follow the same BTF relation as high-mass galaxies. We quantify the scatter in the BTF relation and use this to constrain the allowed elongations of dark matter halo potentials. Methods.We obtained H i synthesis data of 11 dwarf galaxies and derive several independent estimates for the maximum rotation velocity. Results. Constructing a BTF relation using data from the literature for the high-mass end, and galaxies with detected rotation from our sample for the low-mass end results in a BTF with a scatter of 0.33 mag. Conclusions. This scatter constrains the ellipticities of the potentials in the plane of the disks of the galaxies to an upper limit of 0−0.06, indicating that dwarf galaxies are at most only mildly tri-axial. Our results indicate that the BTF relation is a fundamental relation which all rotationally dominated galaxies seem to follow.

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Section: Introductionsupporting

confidence: 80%

“…Frenk et al 1988;Hayashi & Navarro 2006). Trachternach et al (2008) also find that the elongation does not increase towards the center of the galaxies. The tightly correlated BTF relation presented in this paper constrains the ellipticity of galaxy potentials using a different method, but reaches similar results.…”

Section: The Scatter Of the Btfmentioning

confidence: 74%

The baryonic Tully-Fisher relation and its implication for dark matter halos

Trachternach

Blok²,

McGaugh

et al. 2009

A&A

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122

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“…We just briefly note that in NGC 7793 the value of the inclination angle fitted by de Blok et al (2008) is low and presents large variations in adjacent radii, which results in a poorly constrained rotation curve. In NGC 2976 the amplitude of the non-circular motions (Trachternach et al 2008) is correlated with the amplitude of the fit residuals.…”

Section: Distancesmentioning

confidence: 97%

THINGS about MOND

Gentile

Famaey

Blok

2011

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We present an analysis of 12 high-resolution galactic rotation curves from The HI Nearby Galaxy Survey (THINGS) in the context of modified Newtonian dynamics (MOND). These rotation curves were selected to be the most reliable for mass modelling, and they are the highest quality rotation curves currently available for a sample of galaxies spanning a wide range of luminosities. We fit the rotation curves with the "simple" and "standard" interpolating functions of MOND, and we find that the "simple" function yields better results. We also redetermine the value of a 0 , and find a median value very close to the one determined in previous studies, a 0 = (1.22 ± 0.33) × 10 −8 cm s −2 . Leaving the distance as a free parameter within the uncertainty of its best independently determined value leads to excellent quality fits for 75% of the sample. Among the three exceptions, two are also known to give relatively poor fits in Newtonian dynamics plus dark matter. The remaining case (NGC 3198) presents some tension between the observations and the MOND fit, which might, however, be explained by the presence of non-circular motions, by a small distance, or by a value of a 0 at the lower end of our best-fit interval, 0.9 × 10 −8 cm s −2 . The best-fit stellar M/L ratios are generally in remarkable agreement with the predictions of stellar population synthesis models. We also show that the narrow range of gravitational accelerations found to be generated by dark matter in galaxies is consistent with the narrow range of additional gravity predicted by MOND.

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“…The IB(s)m galaxy NGC 2366 forms part of "The H i Nearby Galaxy Survey" (THINGS, Walter et al 2008). Its peculiar kinematics were the subject of several recent publications Oh et al 2008;Trachternach et al 2008;van Eymeren et al 2009a, hereafter dB08, Oh08, CT08, and vE09a). The SB(s)m galaxy NGC 4861 was studied by Wilcots et al (1996) and Thuan et al (2004).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Non-circular motions and the cusp-core discrepancy in dwarf galaxies

Eymeren

Trachternach

Koribalski

et al. 2009

A&A

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Context. The cusp-core discrepancy is one of the major problems in astrophysics. It results from comparing the observed mass distribution of galaxies with the predictions of cold dark matter simulations. The latter predict a cuspy density profile in the inner parts of galaxies, whereas observations of dwarf and low surface brightness galaxies show a constant-density core. Aims. We want to determine the shape of the dark matter potential in the nuclear regions of a sample of six nearby irregular dwarf galaxies. Methods. In order to quantify the amount of non-circular motions that could potentially affect a mass decomposition, we first perform a harmonic decomposition of the H i Hermite velocity fields of all sample galaxies. We then decompose the H i rotation curves into different mass components by fitting NFW and pseudo-isothermal halo models to the H i rotation curves using a χ 2 minimisation. We model the minimum-disc, the minimum-disc + gas, and the maximum-disc cases.Results. The non-circular motions are in all cases studied here of the order of only a few km s −1 (generally corresponding to less than 25% of the local rotation velocity), which means that they do not significantly affect the rotation curves. The observed rotation curves can better be described by the cored pseudo-isothermal halo than by the NFW halo. The slopes of the dark matter density profiles confirm this result and are in good agreement with previous studies. The quality of the fits can often be improved when including baryons, which suggests that they contribute significantly to the inner part of the density profile of dwarf galaxies.

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Dynamical Centers and Noncircular Motions in Things Galaxies: Implications for Dark Matter Halos

Cited by 136 publications

References 45 publications

The baryonic Tully-Fisher relation and its implication for dark matter halos

The baryonic Tully-Fisher relation and its implication for dark matter halos

THINGS about MOND

Non-circular motions and the cusp-core discrepancy in dwarf galaxies

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