Satellite galaxies as better tracers of the Milky Way halo mass

Han, Jiaxin; Wang, Wenting; Li, Zhaozhou

doi:10.1017/s1743921319008020

Cited by 2 publications

(4 citation statements)

References 15 publications

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“…The use of the data-inferred distribution of orbits in place of a gridded library significantly simplifies the inference of the potential, at the cost of losing the flexibility to handle missing dimensions in the data. This method has been used to study the dynamical state of simulated MW halos in [172,173,390]. Their analyses have revealed a stochastic scatter in the best-fit mass and concentration parameters, which can be as large as a factor of 2 when halo stars are used as tracers.…”

Section: Free-form Distribution Functionsmentioning

confidence: 99%

“…While the stochastic bias using stars is large, the bias using dark matter particles is much smaller, σ M ∼ 20%. It is also shown that satellite galaxies have a dynamical state close to dark matter particles, and are thus expected to be better dynamical tracers than halo stars [173].…”

Section: Free-form Distribution Functionsmentioning

confidence: 99%

“…In the presence of phase correlations, the number of independent tracer particles is smaller than the actual number of tracers. This leads to stochastic biases in the parameter estimates, the distribution of which are determined 000000-33 [173], the dynamical state of satellite galaxies is found to be close to that of dark matter particles. As a result, satellite galaxies exhibit a smaller stochastic bias compared to halo stars, as shown in Fig.…”

Section: The Role Of Numerical Simulationsmentioning

confidence: 99%

“…For a fair comparison between satellites and dark matter, the blue dashed ellipse (σ DMsat ) shows the total scatter associated with dark matter particles down-sampled to the have the same number as that of satellites. Figure reproduced from [173].…”

Section: The Role Of Numerical Simulationsmentioning

confidence: 99%

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The mass of our Milky Way

Wang¹,

Han²,

Cautun³

et al. 2020

Sci. China Phys. Mech. Astron.

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122

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We perform an extensive review of the numerous studies and methods used to determine the total mass of the Milky Way. We group the various studies into seven broad classes according to their modeling approaches. The classes include: i) estimating Galactic escape velocity using high velocity objects; ii) measuring the rotation curve through terminal and circular velocities; iii) modeling halo stars, globular clusters and satellite galaxies with the Spherical Jeans equation and iv) with phase-space distribution functions; v) simulating and modeling the dynamics of stellar streams and their progenitors; vi) modeling the motion of the Milky Way, M31 and other distant satellites under the framework of Local Group timing argument; and vii) measurements made by linking the brightest Galactic satellites to their counterparts in simulations. For each class of methods, we introduce their theoretical and observational background, the method itself, the sample of available tracer objects, model assumptions, uncertainties, limits and the corresponding measurements that have been achieved in the past. Both the measured total masses within the radial range probed by tracer objects and the extrapolated virial masses are discussed and quoted. We also discuss the role of modern numerical simulations in terms of helping to validate model assumptions, understanding systematic uncertainties and calibrating the measurements. While measurements in the last two decades show a factor of two scatters, recent measurements using Gaia DR2 data are approaching a higher precision. We end with a detailed discussion of future developments in the field, especially as the size and quality of the observational data will increase tremendously with current and future surveys. In such cases, the systematic uncertainties will be dominant and thus will necessitate a much more rigorous testing and characterization of the various mass determination methods.

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Section: Free-form Distribution Functionsmentioning

confidence: 99%

Section: Free-form Distribution Functionsmentioning

confidence: 99%

Section: The Role Of Numerical Simulationsmentioning

confidence: 99%

Section: The Role Of Numerical Simulationsmentioning

confidence: 99%

See 2 more Smart Citations

The mass of our Milky Way

Wang¹,

Han²,

Cautun³

et al. 2020

Sci. China Phys. Mech. Astron.

Self Cite

122

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What to expect from dynamical modelling of cluster haloes – I. The information content of different dynamical tracers

Han

Wang

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Using hydrodynamical simulations, we study how well the underlying gravitational potential of a galaxy cluster can be modelled dynamically with different types of tracers. In order to segregate different systematics and the effects of varying estimator performances, we first focus on applying a generic minimal assumption method (oPDF) to model the simulated haloes using the full 6-D phasespace information. We show that the halo mass and concentration can be recovered in an ensemble unbiased way, with a stochastic bias that varies from halo to halo, mostly reflecting deviations from steady state in the tracer distribution. The typical systematic uncertainty is ∼0.17 dex in the virial mass and ∼0.17 dex in the concentration as well when dark matter particles are used as tracers. The dynamical state of satellite galaxies are close to that of dark matter particles, while intracluster stars are less in a steady state, resulting in a ∼ 0.26 dex systematic uncertainty in mass. Compared with galactic haloes hosting Milky-Way-like galaxies, cluster haloes show a larger stochastic bias in the recovered mass profiles. We also test the accuracy of using intracluster gas as a dynamical tracer modelled through a generalised hydrostatic equilibrium equation, and find a comparable systematic uncertainty in the estimated mass to that using dark matter. Lastly, we demonstrate that our conclusions are largely applicable to other steady-state dynamical models including the spherical Jeans equation, by quantitatively segregating their statistical efficiencies and robustness to systematics. We also estimate the limiting number of tracers that leads to the systematics-dominated regime in each case.

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Satellite galaxies as better tracers of the Milky Way halo mass

Cited by 2 publications

References 15 publications

The mass of our Milky Way

The mass of our Milky Way

What to expect from dynamical modelling of cluster haloes – I. The information content of different dynamical tracers

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