Physical properties underlying observed kinematics of satellite galaxies

Wojtak, Radosław; Mamon, G. A.

doi:10.1093/mnras/sts203

Cited by 94 publications

(154 citation statements)

References 81 publications

(150 reference statements)

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“…The estimates obtained from the stacked kinematical data of galaxies in clusters (Biviano & Katgert 2004;Wojtak & Lokas 2010) and the satellite galaxies around isolated hosts (Wojtak & Mamon 2012) are fairly compatible with the spherically averaged β profiles from the simulations. We emphasise, however, that this consistency does not imply the fact that β describes the true orbital anisotropy, because stacking kinematical data introduces artificial sphericalisation of the phase-space distribution that is equivalent to measuring β in spherical shells of simulated objects.…”

Section: Observational Constraints On βsupporting

confidence: 73%

Orbital anisotropy in cosmological haloes revisited

Wojtak

Gottlöber

Klypin

2013

Monthly Notices of the Royal Astronomical Society

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The velocity anisotropy of particles inside dark matter (DM) haloes is an important physical quantity, which is required for the accurate modelling of mass profiles of galaxies and clusters of galaxies. It is typically measured using the ratio of the radialto-tangential velocity dispersions at a given distance from the halo centre. However, this measure is insufficient to describe the dynamics of realistic haloes, which are not spherical and are typically quite elongated. Studying the velocity distribution in massive DM haloes in cosmological simulations, we find that in the inner parts of the haloes the local velocity ellipsoids are strongly aligned with the major axis of the halo, the alignment being stronger for more relaxed haloes. In the outer regions of the haloes, the alignment becomes gradually weaker and the orientation is more random. These two distinct regions of different degree of the alignment coincide with two characteristic regimes of the DM density profile: a shallow inner cusp and a steep outer profile that are separated by a characteristic radius at which the density declines as ρ ∝ r −2 . This alignment of the local velocity ellipsoids requires reinterpretation of features found in measurements based on the spherically averaged ratio of the radial-to-tangential velocity dispersions. In particular, we show that the velocity distribution in the central halo regions is highly anisotropic. For cluster-size haloes with mass 10 14 − 10 15 h −1 M ⊙ , the velocity anisotropy along the major axis is nearly independent of radius and is equal to β = 1 − σ 2 perp /σ 2 radial ≈ 0.4, which is significantly larger than the previously estimated spherically averaged velocity anisotropy. The alignment of density and velocity anisotropies, and the radial trends may also have some implications for the mass modelling based on kinematical data of such objects as galaxy clusters or dwarf spheroidals, where the orbital anisotropy is a key element in an unbiased mass inference.

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Section: Observational Constraints On βsupporting

confidence: 73%

Orbital anisotropy in cosmological haloes revisited

Wojtak

Gottlöber

Klypin

2013

Monthly Notices of the Royal Astronomical Society

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“…Rodríguez-Puebla et al 2011;Wojtak & Mamon 2013). However, we do not motivate this model on 6 There is no a priori theoretical reason why ν must lie in the range [-1,1].…”

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confidence: 75%

The Tully–Fisher and mass–size relations from halo abundance matching

Desmond

Wechsler

2015

Mon. Not. R. Astron. Soc.

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The Tully-Fisher relation (TFR) expresses the connection between rotating galaxies and the dark matter haloes they inhabit, and therefore contains a wealth of information about galaxy formation. We construct a general framework to investigate whether models based on halo abundance matching are able to reproduce the observed stellar mass TFR and mass-size relation (MSR), and use the data to constrain galaxy formation parameters. Our model tests a range of plausible scenarios, differing in the response of haloes to disc formation, the relative angular momentum of baryons and dark matter, the impact of selection effects, and the abundance matching parameters. We show that agreement with the observed TFR puts an upper limit on the scatter between galaxy and halo properties, requires weak or reversed halo contraction, and favours selection effects that preferentially eliminate fast-rotating galaxies. The MSR constrains the ratio of the disc to halo specific angular momentum to be approximately in the range 0.6−1.2. We identify and quantify two problems that models of this nature face. (1) They predict too large an intrinsic scatter for the MSR, and (2) they predict too strong an anticorrelation between the TFR and MSR residuals. We argue that resolving these problems requires introducing a correlation between stellar surface density and enclosed dark matter mass. Finally, we explore the expected difference between the TFRs of central and satellite galaxies, finding that in the favoured models this difference should be detectable in a sample of ∼ 700 galaxies.

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“…Solid red line refers to quiescent galaxies at z ∼ 0. Weak lensing data are from Mandelbaum et al (2016;circles), Velander et al (2014;squares), Rodriguez-Puebla et al (2015;triangles), and Hudson et al (2015;hexagons); satellite kinematic data are from Wojtak & Mamon (2013;diamonds) and More et al (2011;pentagons); Hα data for galaxies at z ∼ 0.8 − 2.5 are from Burkert et al (2016;crosses). Blue symbols are for disc-dominated galaxies and red symbols for spheroids.…”

Section: Resultsmentioning

confidence: 99%

Stellar Mass Function of Active and Quiescent Galaxies via the Continuity Equation

Lapi

Mancuso

Bressan

et al. 2017

ApJ

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The continuity equation is developed for the stellar mass content of galaxies, and exploited to derive the stellar mass function of active and quiescent galaxies over the redshift range z ∼ 0 − 8. The continuity equation requires two specific inputs gauged on observations: (i) the star formation rate functions determined on the basis of the latest UV+far-IR/sub-mm/radio measurements; (ii) average star-formation histories for individual galaxies, with different prescriptions for discs and spheroids. The continuity equation also includes a source term taking into account (dry) mergers, based on recent numerical simulations and consistent with observations. The stellar mass function derived from the continuity equation is coupled with the halo mass function and with the SFR functions to derive the star formation efficiency and the main sequence of star-forming galaxies via the abundance matching technique. A remarkable agreement of the resulting stellar mass function for active and quiescent galaxies, of the galaxy main sequence and of the star-formation efficiency with current observations is found; the comparison with data also allows to robustly constrain the characteristic timescales for star formation and quiescence of massive galaxies, the star formation history of their progenitors, and the amount of stellar mass added by in-situ star formation vs. that contributed by external merger events. The continuity equation is shown to yield quantitative outcomes that must be complied by detailed physical models, that can provide a basis to improve the (sub-grid) physical recipes implemented in theoretical approaches and numerical simulations, and that can offer a benchmark for forecasts on future observations with multi-band coverage, as it will become routinely achievable in the era of JWST.

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Physical properties underlying observed kinematics of satellite galaxies

Cited by 94 publications

References 81 publications

Orbital anisotropy in cosmological haloes revisited

Orbital anisotropy in cosmological haloes revisited

The Tully–Fisher and mass–size relations from halo abundance matching

Stellar Mass Function of Active and Quiescent Galaxies via the Continuity Equation

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