The structure of Andromeda II dwarf spheroidal galaxy

Pino, Andrés del; Łokas, Ewa L.; Hidalgo, S. L.; Fouquet, Sylvain

doi:10.1093/mnras/stx1195

Cited by 18 publications

(18 citation statements)

References 45 publications

(84 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Also, [57] shows that smaller galaxies tend to be more spherically symmetric and that dark matter distribution is more spherically symmetric than stellar distribution. Finally, although rotations are detected in several individual objects (see, e.g., [40, [58][59][60]), spectroscopic observations [61][62][63][64][65] show the absence of rotations with velocities comparable with the observed velocity dispersions in dSphs.…”

Section: Methodsmentioning

confidence: 99%

New Model of Density Distribution for Fermionic Dark Matter Halos

Rudakovskyi

Savchenko

2018

Ukr. J. Phys.

View full text Add to dashboard Cite

PACSIn this paper, we formulate a new model of density distribution for halos made of warm dark matter (WDM) particles. The model is described by a single microphysics parameter the mass (or, equivalently, the maximal value of the initial phase-space density distribution) of dark matter particles. Given the WDM particle mass and the parameters of a dark matter density profile at the halo periphery, this model predicts the inner density profile. In case of initial Fermi-Dirac distribution, we successfully reproduce cored dark matter profiles from N -body simulations. Also, we calculate the core radii of warm dark matter halos of dwarf spheroidal galaxies for particle masses mfd = 100, 200, 300 and 400 eV. K e y w o r d s: Dark matter: warm, cold; dark matter halo profile; cores; Navarro-Frenk-White profileThe nature of dark matter the largest gravitating substance in the Universe is not yet identified. Usual (left-handed) neutrinos the only natural dark matter candidate within the Standard Model of particle physics are too light to form the observed large-scale structure of the Universe [1] and the densest dark matter-dominated objects, dwarf spheroidals (dSphs) [2]. So far, many extensions of the Standard Model containing a viable dark matter candidate have been proposed; see, e.g., reviews [3][4][5][6]. In terms of their initial velocities, valid dark matter candidates can be split in two groups 1 (see, e.g., [9]):• cold dark matter (CDM), composed of particles with small (non-relativistic) initial velocities [10,11]; c A.V. RUDAKOVSKYI, D.O. SAVCHENKO, 2018 1 Note that, for some specific dark matter particle candidates, their initial velocity spectrum can be approximated by a mixture of 'cold ' and 'warm' components [7, 8].• warm dark matter (WDM), composed of particles with large (relativistic) initial velocities [12,13].Density distribution of CDM haloes is often described by the Navarro-Frenk-White (NFW) profile [14,15] ρ nfw (r) = ρ s r s r 1 + r rs 2 . (1) Its parameters ρ s and r s are connected with the halo mass M 200 (the mass within the sphere of radius R 200 , within which the average density is 200 times larger than the critical density ρ crit of the Universe) and halo concentration parameter c 200 = R 200 /r s .The phase-space density for CDM haloes becomes infinite towards the halo centre; see, e.g., [16]. For WDM, this is not true: its maximal phase-space density f max is finite at early times and does not increase during halo formation [17]. Usually, density distri-

show abstract

Section: Methodsmentioning

confidence: 99%

New Model of Density Distribution for Fermionic Dark Matter Halos

Rudakovskyi

Savchenko

2018

Ukr. J. Phys.

View full text Add to dashboard Cite

show abstract

“…In both cases, prolate rotation has been argued to be evidence for a recent merger. For example, the peculiar kinematics of And II may be due to a merger at z ∼ 1.75 (Amorisco, Evans & van de Ven 2014;Lokas et al 2014;del Pino et al 2017b;Fouquet et al 2017). In Phoenix, the spatial distribution of the young stars is aligned with the rotation axis/minor axis that is further evidence for a recent merger (Kacharov et al 2017).…”

Section: Search For Rotationmentioning

confidence: 99%

Multiple chemodynamic stellar populations of the Ursa Minor dwarf spheroidal galaxy

Pace

Kaplinghat

Kirby

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present a Bayesian method to identify multiple (chemodynamic) stellar populations in dwarf spheroidal galaxies (dSphs) using velocity, metallicity, and positional stellar data without the assumption of spherical symmetry. We apply this method to a new Keck/Deep Imaging Multi-Object Spectrograph (DEIMOS) spectroscopic survey of the Ursa Minor (UMi) dSph. We identify 892 likely members, making this the largest UMi sample with line-of-sight velocity and metallicity measurements. Our Bayesian method detects two distinct chemodynamic populations with high significance (in logarithmic Bayes factor, ln B ∼ 33). The metal-rich ([Fe/H] = −2.05 ± 0.03) population is kinematically colder (radial velocity dispersion of $\sigma _v=4.9_{-1.0}^{+0.8} \, \mathrm{km} \, \mathrm{s}^{-1}$) and more centrally concentrated than the metal-poor ($[{\rm Fe/H}]=-2.29_{-0.06}^{+0.05}$) and kinematically hotter population ($\sigma _v =11.5_{-0.8}^{+0.9}\, \mathrm{km} \, \mathrm{s}^{-1}$). Furthermore, we apply the same analysis to an independent Multiple Mirror Telescope (MMT)/Hectochelle data set and confirm the existence of two chemodynamic populations in UMi. In both data sets, the metal-rich population is significantly flattened (ϵ = 0.75 ± 0.03) and the metal-poor population is closer to spherical ($\epsilon =0.33_{-0.09}^{+0.12}$). Despite the presence of two populations, we are able to robustly estimate the slope of the dynamical mass profile. We found hints for prolate rotation of order ${\sim}2 \, \mathrm{km} \, \mathrm{s}^{-1}$ in the MMT data set, but further observations are required to verify this. The flattened metal-rich population invalidates assumptions built into simple dynamical mass estimators, so we computed new astrophysical dark matter annihilation (J) and decay profiles based on the rounder, hotter metal-poor population and inferred $\log _{10}{(J(0{^{\circ}_{.}}5)/{\rm GeV^{2} \, cm^{-5}})}\approx 19.1$ for the Keck data set. Our results paint a more complex picture of the evolution of UMi than previously discussed.

show abstract

“…The full description and clustering process is described in del Pino et al (2017b), their section 3.…”

Section: Observationsmentioning

confidence: 99%

“…del Pino et al (2017b) found that approximately 40% of the stars may be part of different substructures, with 985 stars classified into 24 possible circular streams using a MCS = 13. This could indicate that Fornax is a rather complex system with various rotating components and its spheroidal shape is the superposition of stellar components with distinct kinematics (see their figure 13).…”

Section: Tidal Stirring Modelmentioning

confidence: 99%

Detection of Chemo-Kinematical Structures in Leo I

Jara¹,

M.²,

J.³

et al. 2022

Preprint

View full text Add to dashboard Cite

A variety of formation models for dwarf spheroidal (dSph) galaxies have been proposed in the literature, but these generally have not been quantitatively compared with observations. We make use of a new spectroscopic data-set for the Milky Way dSph Leo I, combining 288 stars observed with Magellan/IMACS and existing Keck/DEIMOS data to provide velocity and metallicity measurements for 953 Leo I member stars. We search for chemodynamical patterns in this data-set, mock galaxies consisting of pure random motions, and simulated dwarfs formed via the dissolving star cluster and tidal stirring models. In the Leo I data, we report the detection of 14 candidate streams of stars that may have originated in disrupted star clusters. The angular momentum vectors of these streams are randomly oriented, consistent with the lack of rotation in Leo I. These results are consistent with the predictions of the dissolving cluster model. In contrast, we find fewer candidate stream signals in mock data-sets that lack coherent motions ∼ 99% of the time. The chemodynamical analysis of the tidal stirring simulation produces streams that share a common orientation, which is inconsistent with the Leo I data.

show abstract

The structure of Andromeda II dwarf spheroidal galaxy

Cited by 18 publications

References 45 publications

New Model of Density Distribution for Fermionic Dark Matter Halos

New Model of Density Distribution for Fermionic Dark Matter Halos

Multiple chemodynamic stellar populations of the Ursa Minor dwarf spheroidal galaxy

Detection of Chemo-Kinematical Structures in Leo I

Contact Info

Product

Resources

About