Satellite galaxies as better tracers of the Milky Way halo mass

AbstractThe inference of the Milky Way halo mass requires modelling the phase space structure of dynamical tracers, with different tracers following different models and having different levels of sensitivity to the halo mass. For steady-state models, deviations from steady-state in the tracer distribution lead to an irreducible stochastic bias. This bias is small for satellite galaxies and dark matter particles, but as large as a factor of 2 for halo stars. This is consistent with the picture that satellite galaxies closely trace the underlying phase space distribution of dark matter particles, while halo stars are less phase-mixed. As a result, the use of only ~100 satellite galaxies can achieve a significantly higher accuracy than that achievable with a much larger sample of halo stars.

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Frequency maps as a probe of secular evolution in the Milky Way

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314011211 ◽

2012 ◽

Vol 10 (H16) ◽

pp. 349-349

Author(s):

Monica Valluri

Keyword(s):

Dark Matter ◽

Distribution Function ◽

Phase Space ◽

Milky Way ◽

Space Distribution ◽

Compact Representation ◽

Phase Space Distribution ◽

Secular Evolution ◽

Halo Stars ◽

Stellar Halo

AbstractThe frequency analysis of the orbits of halo stars and dark matter particles from a cosmological hydrodynamical simulation of a disk galaxy from the MUGS collaboration (Stinson et al. 2010) shows that even if the shape of the dark matter halo is nearly oblate, only about 50% of its orbits are on short-axis tubes, confirming a previous result: under baryonic condensation all orbit families can deform their shapes without changing orbital type (Valluri et al. 2010). Orbits of dark matter particles and halo stars are very similar reflecting their common accretion origin and the influence of baryons. Frequency maps provide a compact representation of the 6-D phase space distribution that also reveals the history of the halo (Valluri et al. 2012). The 6-D phase space coordinates for a large population of halo stars in the Milky Way that will be obtained from future surveys can be used to reconstruct the phase-space distribution function of the stellar halo. The similarity between the frequency maps of halo stars and dark matter particles (Fig. 1) implies that reconstruction of the stellar halo distribution function can reveal the phase space distribution of the unseen dark matter particles and provide evidence for secular evolution. MV is supported by NSF grant AST-0908346 and the Elizabeth Crosby grant.

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The Phase Space Structure of Dark Matter Halos

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3994 ◽

2020 ◽

Author(s):

Han Aung ◽

Daisuke Nagai ◽

Eduardo Rozo ◽

Rafael García

Keyword(s):

Dark Matter ◽

Phase Space ◽

Density Profile ◽

Outer Boundary ◽

Space Structure ◽

Space Distribution ◽

Dark Matter Halo ◽

Dark Matter Halos ◽

Sharp Drop ◽

Phase Space Structure

Abstract The phase space structure of dark matter halos can be used to measure the mass of the halo, infer mass accretion rates, and probe the effects of modified gravity. Previous studies showed that the splashback radius can be measured in position space using a sharp drop in the density profile. Using N-body simulations, we model the distribution of the kinematically distinct infalling and orbiting populations of subhalos and halos. We show that the two are mixed spatially all the way to redge, which extends past the splashback radius defined by the drop in the spherically averaged density profile. This edge radius can be interpreted as a radius which contains a fixed fraction of the apocenters of dark matter particles. Our results highlight the possibility of measuring the outer boundary of a dark matter halo using its phase space structure and provide a firm theoretical foundation to the satellite galaxy model adopted in the companion paper (Tomooka et al. 2020), where we analyzed the phase space distribution of SDSS redMaPPer clusters.

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Constraining the Milky Way Mass Profile with Phase-space Distribution of Satellite Galaxies

The Astrophysical Journal ◽

10.3847/1538-4357/ab84f0 ◽

2020 ◽

Vol 894 (1) ◽

pp. 10 ◽

Cited By ~ 6

Author(s):

Zhao-Zhou Li ◽

Yong-Zhong Qian ◽

Jiaxin Han ◽

Ting S. Li ◽

Wenting Wang ◽

...

Keyword(s):

Phase Space ◽

Milky Way ◽

Space Distribution ◽

Phase Space Distribution ◽

Mass Profile ◽

Satellite Galaxies

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Phase-space structure analysis of self-gravitating collisionless spherical systems

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833460 ◽

2018 ◽

Vol 621 ◽

pp. A8 ◽

Cited By ~ 2

Author(s):

A. Halle ◽

S. Colombi ◽

S. Peirani

Keyword(s):

Steady State ◽

Phase Space ◽

Spiral Structure ◽

Mean Field ◽

Space Structure ◽

Space Distribution ◽

Coarse Grained ◽

Quasi Steady State ◽

Mean Field Limit ◽

Relaxation Phase

In the mean field limit, isolated gravitational systems often evolve towards a steady state through a violent relaxation phase. One question is to understand the nature of this relaxation phase, in particular the role of radial instabilities in the establishment/destruction of the steady profile. Here, through a detailed phase-space analysis based both on a spherical Vlasov solver, a shell code, and a N-body code, we revisit the evolution of collisionless self-gravitating spherical systems with initial power-law density profiles ρ(r) ∝ rn, 0 ≤ n ≤ −1.5, and Gaussian velocity dispersion. Two sub-classes of models are considered, with initial virial ratios η = 0.5 (“warm”) and η = 0.1 (“cool”). Thanks to the numerical techniques used and the high resolution of the simulations, our numerical analyses are able, for the first time, to show the clear separation between two or three well-known dynamical phases: (i) the establishment of a spherical quasi-steady state through a violent relaxation phase during which the phase-space density displays a smooth spiral structure presenting a morphology consistent with predictions from self-similar dynamics, (ii) a quasi-steady-state phase during which radial instabilities can take place at small scales and destroy the spiral structure but do not change quantitatively the properties of the phase-space distribution at the coarse grained level, and (iii) relaxation to a non-spherical state due to radial orbit instabilities for n ≤ −1 in the cool case.

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Self-consistent phase-space distribution function for the anisotropic dark matter halo of the Milky Way

Physical Review D ◽

10.1103/physrevd.89.063531 ◽

2014 ◽

Vol 89 (6) ◽

Cited By ~ 33

Author(s):

Mattia Fornasa ◽

Anne M. Green

Keyword(s):

Dark Matter ◽

Distribution Function ◽

Phase Space ◽

Milky Way ◽

Space Distribution ◽

Dark Matter Halo ◽

Phase Space Distribution ◽

Self Consistent

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FOLLOWING THE COSMIC EVOLUTION OF PRISTINE GAS. I. IMPLICATIONS FOR MILKY WAY HALO STARS

The Astrophysical Journal ◽

10.3847/1538-4357/834/1/23 ◽

2016 ◽

Vol 834 (1) ◽

pp. 23 ◽

Cited By ~ 19

Author(s):

Richard Sarmento ◽

Evan Scannapieco ◽

Liubin Pan

Keyword(s):

Milky Way ◽

Halo Stars ◽

Cosmic Evolution ◽

Milky Way Halo

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A comparative study of satellite galaxies in Milky Way-like galaxies from HSC, DECaLS, and SDSS

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3495 ◽

2020 ◽

Vol 500 (3) ◽

pp. 3776-3801

Author(s):

Wenting Wang ◽

Masahiro Takada ◽

Xiangchong Li ◽

Scott G Carlsten ◽

Ting-Wen Lan ◽

...

Keyword(s):

Dark Matter ◽

Milky Way ◽

Statistical Study ◽

Satellite System ◽

Large Scatter ◽

Local Universe ◽

Good Representative ◽

Luminosity Functions ◽

Satellite Galaxies ◽

Good Agreement

ABSTRACT We conduct a comprehensive and statistical study of the luminosity functions (LFs) for satellite galaxies, by counting photometric galaxies from HSC, DECaLS, and SDSS around isolated central galaxies (ICGs) and paired galaxies from the SDSS/DR7 spectroscopic sample. Results of different surveys show very good agreement. The satellite LFs can be measured down to MV ∼ −10, and for central primary galaxies as small as 8.5 < log10M*/M⊙ < 9.2 and 9.2 < log10M*/M⊙ < 9.9, which implies there are on average 3–8 satellites with MV < −10 around LMC-mass ICGs. The bright end cutoff of satellite LFs and the satellite abundance are both sensitive to the magnitude gap between the primary and its companions, indicating galaxy systems with larger magnitude gaps are on average hosted by less massive dark matter haloes. By selecting primaries with stellar mass similar to our Milky Way (MW), we discovered that (i) the averaged satellite LFs of ICGs with different magnitude gaps to their companions and of galaxy pairs with different colour or colour combinations all show steeper slopes than the MW satellite LF; (ii) there are on average more satellites with −15 < MV < −10 than those in our MW; (iii) there are on average 1.5 to 2.5 satellites with MV < −16 around ICGs, consistent with our MW; (iv) even after accounting for the large scatter predicted by numerical simulations, the MW satellite LF is uncommon at MV > −12. Hence, the MW and its satellite system are statistically atypical of our sample of MW-mass systems. In consequence, our MW is not a good representative of other MW-mass galaxies. Strong cosmological implications based on only MW satellites await additional discoveries of fainter satellites in extra-galactic systems. Interestingly, the MW satellite LF is typical among other MW-mass systems within 40 Mpc in the local Universe, perhaps implying the Local Volume is an underdense region.

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