Galactic stellar haloes in the CDM model

By A. Cooper, Shaun Cole, Carlos S. Frenk, Simon D. M. White, G. Lucia, A. Helmi, A. Benson, John C. Helly, Adrian Jenkins, J. Navarro and 2 more. 2009

454 citations recorded by the source corpus.

We present six simulations of galactic stellar haloes formed by the tidal disruption of accreted dwarf galaxies in a fully cosmological setting. Our model is based on the Aquarius project, a suite of high-resolution N-body simulations of individual dark matter haloes. We tag subsets of particles in these simulations with stellar populations predicted by the galform semi-analytic model. Our method self-consistently tracks the dynamical evolution and disruption of satellites from high redshift. The luminosity function (LF) and structural properties of surviving satellites, which agree well with observations, suggest that this technique is appropriate. We find that accreted stellar haloes are assembled between 1 < z < 7 from less than five significant progenitors. These progenitors are old, metal-rich satellites with stellar masses similar to the brightest Milky Way dwarf spheroidals (10^(7)–10^(8) M_⊙). In contrast to previous stellar halo simulations, we find that several of these major contributors survive as self-bound systems to the present day. Both the number of these significant progenitors and their infall times are inherently stochastic. This results in great diversity among our stellar haloes, which amplifies small differences between the formation histories of their dark halo hosts. The masses (~10^(8)–10^(9) M_⊙) and density/surface-brightness profiles of the stellar haloes (from 10 to 100 kpc) are consistent with expectations from the Milky Way and M31. Each halo has a complex structure, consisting of well-mixed components, tidal streams, shells and other subcomponents. This structure is not adequately described by smooth models. The central regions (<10 kpc) of our haloes are highly prolate (c/a ~ 0.3), although we find one example of a massive accreted thick disc. Metallicity gradients in our haloes are typically significant only where the halo is built from a small number of satellites. We contrast the ages and metallicities of halo stars with surviving satellites, finding broad agreement with recent observations.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Instrumentation

View Paper: https://www.semanticscholar.org/paper/493626d11be91b7799b210b1e75a5b055de20199

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Citations in the corpus

The Milky Way stellar halo out to 40 kpc: squashed, broken but smooth (2011, methodology): “This has been seen as vindication of modern theories of c© 2011 RAS galaxy formation, which predict that stellar haloes are built p almost exclusively from the debris of disrupting satellites (e.g. Bullock & Johnston 2005; De Lucia & Helmi 2008; Cooper et al. 2010).”
The impact of dark matter cusps and cores on the satellite galaxy population around spiral galaxies (2010, background): “In practice, this is difficult because, in spite of strong theoretical efforts (e.g. Macció et al. 2009; Cooper et al. 2009), the processes that shape the baryonic properties of satellite galaxies during their formation and later accretion are still rather uncertain.”
The Dark Matter Crisis: Falsification of the Current Standard Model of Cosmology (2012, unknown): “…Kang & Moore (2009); Koposov et al. (2009); Okamoto& Frenk (2009); Kirby et al. (2009); Shaya et al. (2009); Busha et al. (2010); Primack (2009); Macciò & Fontanot (2010); Macciò et al. (2010); Cooper et al. (2010); Deason et al. (2011); Nichols & BlandHawthorn (2011); Font et al. (2011).”
Chemical signatures of formation processes in the stellar populations of simulated galaxies (2011, background): “In particular, the masses of the disrupted satellites vary from halo to halo (e.g. Cooper et al. 2010) and these differences could be reflected in the chemical patterns.”
Subhaloes going Notts: the subhalo‐finder comparison project (2012, background): “…haloes exists within bound substructures (e.g. Gao et l. 2004; De Lucia et al. 2004; Contini et al. 2011) and a substantial part of the host halo has formed from disrupted subhalo material (e.g. Gill et al. 2004; Knebe et al. 2005; Warnick et al. 2008; Cooper et al. 2010; Libeskind et al. 2011).”
The biggest splash (2019, background): “…loose definition of a halo) can be either accreted from smaller satellites (see e.g. Johnston, Hernquist & Bolte 1996; Helmi & White 1999; Bullock & Johnston 2005; Cooper et al. 2010) or born in situ (Zolotov et al. 2009; McCarthy et al. 2012; Tissera, White & Scannapieco 2012; Cooper et al. 2015).”
The Aquila comparison project: the effects of feedback and numerical methods on simulations of galaxy formation (2011, methodology): “9 compares the stellar half-mass radii of simulated galaxies with the size of observed galaxies of similar stellar mass,5 as well as with the predictions of the GALFORM and L-GALAXIES semi-analytic models and the Milky Way, for reference.”
MULTI-ELEMENT ABUNDANCE MEASUREMENTS FROM MEDIUM-RESOLUTION SPECTRA. II. CATALOG OF STARS IN MILKY WAY DWARF SATELLITE GALAXIES (2010, background): “The individual stellar populations are difficult to disentangle, especially in the inner halo (e.g., Cooper et al. 2010).”
Using chemical tagging to redefine the interface of the Galactic disc and halo (2015, background): “Simulations of the Galactic halo (e.g. Bullock & Johnston 2005; Zolotov et al. 2009; Cooper et al. 2010) have indicated that the halo may have been constructed primarily through a combination of dissipative collapse and accretion events of massive systems.”
The missing massive satellites of the Milky Way (2012, background): “…the relatively small number of subhalos massive enough to host luminous galaxies (see, e.g., Kauffmann et al. 1993; Bullock et al. 2000; Benson et al. 2002; Somerville ⋆ Email: jie.wang@durham.ac.uk 2002; Cooper et al. 2010; Li et al. 2010; Macciò et al. 2010; Guo et al. 2011; Font et al. 2011).”
STRUCTURE AND KINEMATICS OF THE STELLAR HALOS AND THICK DISKS OF THE MILKY WAY BASED ON CALIBRATION STARS FROM SLOAN DIGITAL SKY SURVEY DR7 (2009, methodology): “Cooper et al. (2009) have also conducted simulations of the formation of stellar halos within the ΛCDM paradigm, offering a number of improvements over previous efforts.”
Ultra–Low Surface Brightness Imaging with the Dragonfly Telephoto Array (2014, background): “Detailed simulations of tidal debris around Milky Way-like galaxies (Johnston et al. 2008; Cooper et al. 2010) and elliptical galaxies (Naab et al. 2007) indicate that the majority of accreted stars live at surface brightness levels & 29 mag arcsec−2.”
The current status of galaxy formation (2012, background): “Simulations provide a convincing demonstration that we are seeing tidal disruption in action (Cooper et al., 2010).”
Local-Group tests of dark-matter concordance cosmology - Towards a new paradigm for structure formation (2010, methodology): “Cooper et al. (2010) study CDM model satellites in individual numerical models of dark matter halos computed within the Aquarius project.”
The bifurcated age–metallicity relation of Milky Way globular clusters and its implications for the accretion history of the galaxy (2013, result): “We also note the good agreement with the early estimates from Unavane, Wyse & Gilmore (1996), and again the simulations of Cooper et al. (2010) who found that MW sized galaxies could accrete 20 − 80% of their stellar halo mass from the most massive progenitor dwarf galaxy in the mass range of 107 −…”
Cosmological simulations of the formation of the stellar haloes around disc galaxies (2011, methodology): “The fact that our total (accreted+in situ) profiles show evidence for an increase in normalisation at small radii (at r ≈ 30 kpc), whereas Cooper et al. (2010) find, if anything, a slight flattening, suggests that in situ star formation also plays an important role at small radii.”
Co-formation of the disc and the stellar halo (2018, background): “Even though, crudely, the physics of the formation and evolution of the dark and the stellar halos are the same, their redshift z = 0 proper- ties may be drastically different due to the highly stochastic nature of the stellar halo accretion (see e.g. Cooper et al. 2010).”