A Milky Way with a massive, centrally concentrated thick disc:   new Galactic mass models for orbit computations

Pouliasis, E.; Matteo, P. Di; Haywood, M.

doi:10.1051/0004-6361/201527346

Cited by 60 publications

(68 citation statements)

References 50 publications

(87 reference statements)

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“…where R is the radius in the galactocentric cylindrical coordinates, and R d , z d are the characteristic scales of the profile. Whenever we fix the baryonic components of this model in our analyses, we set all the parameters at the same values used by [1], as described in [10], with M bulge = 1.067 × = 0.8 kpc for the disks. The same parametric setting is used for the mean values of the Gaussian priors when we allow the baryonic components to vary in the fits.…”

Section: Baryonic Model B1mentioning

confidence: 99%

“…The same parametric setting is used for the mean values of the Gaussian priors when we allow the baryonic components to vary in the fits. The chosen values of the baryonic components are motivated by several observations, among which [10] used the local baryonic surface and volume densities of the Milky Way. The used observations are based on different studies [9,[13][14][15][16][17].…”

Section: Baryonic Model B1mentioning

confidence: 99%

“…Defining η as the parameter γ for the gNFW profile and α for the Einasto profile, the connection between the varied dark matter quantities of our analyses, {M 200 , c 200 , η}, and a given dark matter profile ρ DM (r, r s , ρ 0 , η), is made through Eqs. (9), (10) and…”

Section: Dark Matter Profilesmentioning

confidence: 99%

See 2 more Smart Citations

On the estimation of the local dark matter density using the rotation curve of the Milky Way

Salas

Malhan

Freese

et al. 2019

J. Cosmol. Astropart. Phys.

132

136

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The rotation curve of the Milky Way is commonly used to estimate the local dark matter density ρDM, . However, the estimates are subject to the choice of the distribution of baryons needed in this type of studies. In this work we explore several Galactic mass models that differ in the distribution of baryons and dark matter, in order to determine ρDM, . For this purpose we analyze the precise rotation curve measurements of the Milky Way up to ∼ 25 kpc from the Galactic centre obtained from Gaia DR2 [1]. We find that the estimated value of ρDM, stays robust to reasonable changes in the spherical dark matter halo. However, we show that ρDM, is affected by the choice of the model for the underlying baryonic components. In particular, we find that ρDM, is mostly sensitive to uncertainties in the disk components of the Galaxy. We also show that, when choosing one particular baryonic model, the estimate of ρDM, has an uncertainty of only about 10% of its best-fit value, but this uncertainty gets much bigger when we also consider the variation of the baryonic model. In particular, the rotation curve method does not allow to exclude the presence of an additional very thin component, that can increase ρDM, by more than a factor of 8. Therefore, we conclude that exclusively using the rotation curve of the Galaxy is not enough to provide a robust estimate of ρDM, . For all the models that we study without the presence of an additional thin component, our resulting estimates of the local dark matter density take values in the range ρDM, 0.3-0.4 GeV/cm 3 , consistent with many of the estimates in the literature.

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Section: Baryonic Model B1mentioning

confidence: 99%

Section: Baryonic Model B1mentioning

confidence: 99%

See 1 more Smart Citation

On the estimation of the local dark matter density using the rotation curve of the Milky Way

Salas

Malhan

Freese

et al. 2019

J. Cosmol. Astropart. Phys.

132

136

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“…With these quantities, the LSR has positive LZ = 1902 kpc km s −1 . To calculate the potential energy, we used model 2 from Pouliasis et al (2017) for the gravitational potential, which yields 230 km s −1 for the circular velocity at 8.2 kpc. With this potential and the above velocity, the LSR has Etot = −1.72 × 10 5 km 2 s −2 .…”

Section: Radial Velocity Measurementsmentioning

confidence: 99%

Local RR Lyrae stars: native and alien

Zinn

Chen

Layden

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Measurements of [Fe/H] and radial velocity are presented for 89 RR Lyrae (RRL) candidates within 6 kpc of the Sun. After the removal of two suspected non-RRL, these stars were added to an existing database, which yielded 464 RRL with [Fe/H] on a homogeneous scale. Using data from the Gaia satellite (Data Release 2), we calculated the positions and space velocities for this sample. These data confirm the existence of a thin-disc of RRL with [α/Fe]∼ solar. The majority of the halo RRL with large total energies have near zero angular momenta about the Z axis. Kinematically these stars closely resemble the Gaia-Sausage/Gaia-Enceladus stars that others have proposed are debris from the merger of a large galaxy with the Milky Way. The metallicity and period distributions of the RRL and their positions in the period-amplitude diagram suggest that this disrupted galaxy was as massive as the Large Magellanic Cloud and possibly greater.

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“…The derived NFW halo parameters from our escape velocity measurement. Here, we assume a bulge and 2-component disc potential as given inPouliasis et al (2017) (also used inEilers et al 2018). The gray filled contour shows the 68% confidence, and the solid gray line shows the 95% confidence region.…”

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confidence: 99%

The local high-velocity tail and the Galactic escape speed

Deason

Fattahi

Belokurov

et al. 2019

Monthly Notices of the Royal Astronomical Society

117

124

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We model the fastest moving (v tot > 300 km s −1 ) local (D 3 kpc) halo stars using cosmological simulations and 6-dimensional Gaia data. Our approach is to use our knowledge of the assembly history and phase-space distribution of halo stars to constrain the form of the high velocity tail of the stellar halo. Using simple analytical models and cosmological simulations, we find that the shape of the high velocity tail is strongly dependent on the velocity anisotropy and number density profile of the halo stars -highly eccentric orbits and/or shallow density profiles have more extended high velocity tails. The halo stars in the solar vicinity are known to have a strongly radial velocity anisotropy, and it has recently been shown the origin of these highly eccentric orbits is the early accretion of a massive (M star ∼ 10 9 M ⊙ ) dwarf satellite. We use this knowledge to construct a prior on the shape of the high velocity tail. Moreover, we use the simulations to define an appropriate outer boundary of 2r 200 , beyond which stars can escape. After applying our methodology to the Gaia data, we find a local (r 0 = 8.3 kpc) escape speed of v esc (r 0 ) = 528 +24 −25 km s −1 . We use our measurement of the escape velocity to estimate the total Milky Way mass, and dark halo concentration: M 200,tot = 1.00 +0.31 −0.24 × 10 12 M ⊙ , c 200 = 10.9 +4.4 −3.3 . Our estimated mass agrees with recent results in the literature that seem to be converging on a Milky Way mass of M 200,tot ∼ 10 12 M ⊙ .

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A Milky Way with a massive, centrally concentrated thick disc: new Galactic mass models for orbit computations

Cited by 60 publications

References 50 publications

On the estimation of the local dark matter density using the rotation curve of the Milky Way

On the estimation of the local dark matter density using the rotation curve of the Milky Way

Local RR Lyrae stars: native and alien

The local high-velocity tail and the Galactic escape speed

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