Constrained simulations of the Local Group: on the radial distribution of substructures

Libeskind, Noam I.; Yepes, Gustavo; Knebe, Alexander; Gottlöber, Stefan; Hoffman, Yehuda; Knollmann, Steffen R.

doi:10.1111/j.1365-2966.2009.15766.x

Cited by 95 publications

(140 citation statements)

References 59 publications

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“…These simulations have been presented by Gottloeber et al (2010) and several aspects of them have been reported and discussed in recent work (e.g., Libeskind et al 2010;Knebe et al 2011;Di Cintio et al 2012;Benítez-Llambay et al 2013. We discuss briefly the main features relevant to our analysis below and refer the interested reader to those papers for details.…”

Section: The Clues Simulationmentioning

confidence: 93%

Mergers and the outside-in formation of dwarf spheroidals

Benítez-Llambay¹,

Navarro²,

Abadi³

et al. 2015

Mon. Not. R. Astron. Soc.

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We use a cosmological simulation of the formation of the Local Group to explore the origin of age and metallicity gradients in dwarf spheroidal galaxies. We find that a number of simulated dwarfs form "outside-in", with an old, metal-poor population that surrounds a younger, more concentrated metal-rich component, reminiscent of dwarf spheroidals like Sculptor or Sextans. We focus on a few examples where stars form in two populations distinct in age in order to elucidate the origin of these gradients. The spatial distributions of the two components reflect their diverse origin; the old stellar component is assembled through mergers, but the young population forms largely in situ. The older component results from a first episode of star formation that begins early but is quickly shut off by the combined effects of stellar feedback and reionization. The younger component forms when a late accretion event adds gas and reignites star formation. The effect of mergers is to disperse the old stellar population, increasing their radius and decreasing their central density relative to the young population. We argue that dwarf-dwarf mergers offer a plausible scenario for the formation of systems with multiple distinct populations and, more generally, for the origin of age and metallicity gradients in dwarf spheroidals.

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Section: The Clues Simulationmentioning

confidence: 93%

Mergers and the outside-in formation of dwarf spheroidals

Benítez-Llambay¹,

Navarro²,

Abadi³

et al. 2015

Mon. Not. R. Astron. Soc.

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“…CLUES runs evolve realizations of the local Universe that mimic their large-scale mass distribution and the tidal fields operating on them. These simulations have been presented in Gottloeber et al (2010) and different aspects of them have been reported in recent work (eg., Libeskind et al 2010;Di Cintio et al 2012;Knebe et al 2011;Benítez-Llambay et al 2013;Yepes et al 2014). We include here a brief description for completeness; full details may be consulted in the above references or in the webpage 3 of the project.…”

Section: Numerical Simulationsmentioning

confidence: 99%

The imprint of reionization on the star formation histories of dwarf galaxies

Benitez-Llambay

Navarro

Abadi

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We explore the impact of cosmic reionization on nearby isolated dwarf galaxies using a compilation of star formation histories estimated from deep HST data and a cosmological hydrodynamical simulation of the Local Group. The nearby dwarfs show a wide diversity of star formation histories; from ancient systems that have largely completed their star formation ∼ 10 Gyr ago to young dwarfs that have formed the majority of their stars in the past ∼ 5 Gyr to two-component systems characterized by the overlap of comparable numbers of old and young stars. Taken as an ensemble, star formation in nearby dwarfs dips to lower-thanaverage rates at intermediate times (4 < t/Gyr < 8), a feature that we trace in the simulation to the effects of cosmic reionization. Reionization heats the gas and drives it out of the shallow potential wells of low mass halos, affecting especially those below a sharp mass threshold that corresponds to a virial temperature of ∼ 2 × 10 4 K at z reion . The loss of baryons leads to a sharp decline in the star forming activity of early-collapsing systems, which, compounded by feedback from early star formation, empties halos of gas and leaves behind systems where a single old stellar component prevails. In halos below the threshold at z reion , reionization heating leads to a delay in the onset of star formation that lasts until the halo grows massive enough to allow some of the remaining gas to cool and form stars. Young stellar components therefore dominate in dwarfs whose halos assemble late and thus form few stars before reionization. Two-component systems may be traced to late mergers of individual examples of the two aforementioned cases. The relative dearth of intermediate-age stars in nearby dwarfs might thus be the clearest signature yet identified of the imprint of cosmic reionization on the star formation history of dwarf galaxies.

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“…Only particles between 5 h −1 Mpc and 80 h −1 Mpc from the observer, which is placed at the right distance from the Virgo cluster, are taken into account. A proper description of the density field in the innermost 5 h −1 Mpc, although affected by random density fluctuations at this scale, would require a higher resolution simulation to be resolved properly (as in Libeskind et al 2010). Thus this region empty of massive large structures is not considered here.…”

Section: Constrained Simulations Of the Local Universementioning

confidence: 99%

DARK MATTER DECAY AND ANNIHILATION IN THE LOCAL UNIVERSE: CLUES FROM FERMI

Cuesta

Jeltema

Zandanel

et al. 2010

ApJ

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We present all-sky simulated Fermi maps of γ -rays from dark matter (DM) decay and annihilation in the local universe. The DM distribution is obtained from a constrained cosmological simulation of the neighboring large-scale structure provided by the CLUES project. The DM fields of density and density squared are then taken as an input for the Fermi observation simulation tool to predict the γ -ray photon counts that Fermi would detect in 5 years of an all-sky survey for given DM models. Signal-to-noise ratio (S/N) sky maps have also been obtained by adopting the current Galactic and isotropic diffuse background models released by the Fermi Collaboration. We point out the possibility for Fermi to detect a DM γ -ray signal in local extragalactic structures. In particular, we conclude here that Fermi observations of nearby clusters (e.g., Virgo and Coma) and filaments are expected to give stronger constraints on decaying DM compared to previous studies. As an example, we find a significant S/N in DM models with a decay rate fitting the positron excess as measured by PAMELA. This is the first time that DM filaments are shown to be promising targets for indirect detection of DM. On the other hand, the prospects for detectability of annihilating DM in local extragalactic structures are less optimistic even with extreme cross-sections. We make the DM density and density squared maps publicly available online.

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Constrained simulations of the Local Group: on the radial distribution of substructures

Cited by 95 publications

References 59 publications

Mergers and the outside-in formation of dwarf spheroidals

Mergers and the outside-in formation of dwarf spheroidals

The imprint of reionization on the star formation histories of dwarf galaxies

DARK MATTER DECAY AND ANNIHILATION IN THE LOCAL UNIVERSE: CLUES FROM FERMI

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