The RAVE survey: constraining the local Galactic escape speed

Smith, M. C.; Ruchti, G.; Helmi, Amina; Wyse, Rosemary F. Ġ.; Fulbright, Jon P.; Freeman, K. C.; Navarro, Julio F.; Seabroke, G. M.; Steinmetz, Matthias; Williams, M.; Bienaymé, O.; Binney, James; Bland-Hawthorn, Joss; Dehnen, Walter; Gibson, Brad K.; Gilmore, G.; Grebel, Eva K.; Munari, U.; Parker, Quentin A.; Scholz, R.‐D.; Siebert, A.; Watson, Fred; Zwitter, T.

doi:10.1111/j.1365-2966.2007.11964.x

Cited by 596 publications

(467 citation statements)

References 56 publications

(73 reference statements)

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“…For example, Smith et al (2007) used this as a critical assumption for their technique to estimate the mass of the Galaxy.…”

Section: Discussionmentioning

confidence: 99%

“…However, in the real Milky Way the escape speed is still uncertain to a considerable degree since neither the total mass (1−2 × 10 12 M , e.g. Smith et al 2007;Xue et al 2008;Guo et al 2010;Boylan-Kolchin et al 2011;Przybilla et al 2010b) nor the global shape of the gravitational potential (Law et al 2009) is measured accurately. Moreover, the asymmetry of the Galaxy introduces a direction dependency.…”

Section: Observable Properties From the Simulationsmentioning

confidence: 99%

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Kinematics in galactic tidal tails

Piffl¹,

Williams²,

Steinmetz³

2011

A&A

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Context. Recent observations of stars with unusually high radial velocities in the Galactic stellar halo have raised new interest in so-called hypervelocity stars. Traditionally, it is assumed that the velocities of these stars could only come from an interaction with the supermassive black hole in the Galactic center. It was suggested that stars stripped off a disrupted satellite galaxy could reach similar velocities and leave the Galaxy. Aims. In this work we study the kinematics of tidal debris stars in detail to investigate the implications of the new scenario and the probability that the observed sample of hypervelocity stars could partly develop out of such a galaxy collision. Methods. We used a suite of N-body simulations following the encounter of a satellite galaxy with its Milky Way-type host galaxy to gather statistics on the properties of stripped-off stars. We study especially the orbital energy distribution of this population. Results. We quantify the typical pattern in angular and phase space formed by the debris stars. We further develop a simple stripping model to predict the kinematics of stripped-off stars. We show that the distribution of orbital energies in the tidal debris takes a typical form that can be described quite accurately by a simple function. Based on this we develop a method predicting the energy distribution that allows us to evaluate the significance and the implications of highvelocity stars in satellite tidal debris. Conclusions. Generally the tidal collisions of satellite galaxy produce stars that escape into intragalactic space even if the satellite itself is on a bound orbit. The main parameters determining the maximum energy kick a tidal debris star can get is the initial mass of the satellite and only to a lower extent its orbit. Main contributors to an unbound stellar population created in this way are massive satellites (M sat > 10 9 M ). We thus expect intragalactic stars to have a metallicity higher than the surviving satellite population of the Milky Way. However, the probability that the observed HVS population is significantly contaminated by tidal debris stars appears low in light of our results.

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“…For example, Smith et al (2007) used this as a critical assumption for their technique to estimate the mass of the Galaxy.…”

Section: Discussionmentioning

confidence: 99%

Section: Observable Properties From the Simulationsmentioning

confidence: 99%

Kinematics in galactic tidal tails

Piffl¹,

Williams²,

Steinmetz³

2011

A&A

Self Cite

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show abstract

“…The gaussian priors and the astrophysical likelihood are given in details in [87]. Only in the case of Maxwellian velocity distribution we do not vary the astrophysical observable in their allowed range but keep them fixed at their mean values, which arev 0 = 230 kms −1 [97,98], v esc = 544 kms −1 [99,100] andρ = 0.4 GeVcm −3 [101,102].…”

Section: Experiments Mcmc Parameter Priormentioning

confidence: 99%

Asymmetric inelastic inert doublet dark matter from triplet scalar leptogenesis

Arina

Sahu

2012

Nuclear Physics B

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Abstract. The nature of dark matter (DM) particles and the mechanism that provides their measured relic abundance are currently unknown. In this paper we investigate inert scalar and vector like fermion doublet DM candidates with a charge asymmetry in the dark sector, which is generated by the same mechanism that provides the baryon asymmetry, namely baryogenesis-via-leptogenesis induced by decays of scalar triplets. At the same time the model gives rise to neutrino masses in the ballpark of oscillation experiments via type II seesaw. We discuss possible sources of depletion of asymmetry in the DM and visible sectors and solve the relevant Boltzmann equations for quasi-equilibrium decay of triplet scalars. A Monte-Carlo-Markov-Chain analysis is performed for the whole parameter space. The survival of the asymmetry in the dark sector leads to inelastic scattering off nuclei. We then apply bayesian statistic to infer the model parameters favoured by the current experimental data, in particular the DAMA annual modulation and Xenon100 exclusion limit. The latter strongly disfavours asymmetric scalar doublet DM of mass O( TeV) as required by DM-DM oscillations, while an asymmetric vector like fermion doublet DM with mass around 100 GeV is a good candidate for DAMA annual modulation yet satisfying the constraints from Xenon100 data.

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“…In the solar neighbourhood, the potential can also be analysed by measuring the Galactic escape speed of high velocity stars (e.g., Smith et al 2007;Famaey et al 2007a), the force perpendicular to the Galactic plane (e.g., Oort 1960;Crézé et al 1998;Siebert et al 2003;Nipoti et al 2007;Holmberg & Flynn 2000, 2004, the coupling between the three components of the velocity distribution in the solar neighbourhood (e.g., Bienaymé 1999), or the orientation of the velocity ellipsoid above the Galactic plane (Ollongren 1962;Hori & Liu 1963;Lynden-Bell 1962;Siebert et al 2008). In the future, much progress is still expected to be made in our understanding of the Galactic potential with the advent of the JASMINE and GAIA missions.…”

Section: Introductionmentioning

confidence: 99%

Galactic kinematics with modified Newtonian dynamics

Bienaymé

Famaey

et al. 2009

A&A

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We look for observational signatures that could discriminate between Newtonian and modified Newtonian (MOND) dynamics in the Milky Way, in view of the advent of large astrometric and spectroscopic surveys. Indeed, a typical signature of MOND is an apparent disk of "phantom" dark matter, which is uniquely correlated with the visible disk-density distribution. Due to this phantom dark disk, Newtonian models with a spherical halo have different signatures from MOND models close to the Galactic plane. The models can thus be differentiated by measuring dynamically (within Newtonian dynamics) the disk surface density at the solar radius, the radial mass gradient within the disk, or the velocity ellipsoid tilt angle above the Galactic plane. Using the most realistic possible baryonic mass model for the Milky Way, we predict that, if MOND applies, the local surface density measured by a Newtonist will be approximately 78 M /pc 2 within 1.1 kpc of the Galactic plane, the dynamically measured disk scale-length will be enhanced by a factor of 1.25 with respect to the visible disk scale-length, and the local vertical tilt of the velocity ellipsoid at 1 kpc above the plane will be approximately 6 degrees. None of these tests can be conclusive for the present-day accuracy of Milky Way data, but they will be of prime interest with the advent of large surveys such as GAIA.

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The RAVE survey: constraining the local Galactic escape speed

Cited by 596 publications

References 56 publications

Kinematics in galactic tidal tails

Kinematics in galactic tidal tails

Asymmetric inelastic inert doublet dark matter from triplet scalar leptogenesis

Galactic kinematics with modified Newtonian dynamics

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