ENRICHMENT OF<i>r</i>-PROCESS ELEMENTS IN DWARF SPHEROIDAL GALAXIES IN CHEMO-DYNAMICAL EVOLUTION MODEL

Hirai, Yutaka; Ishimaru, Yuhri; Saitoh, Takayuki R.; Fujii, Michiko S.; Hidaka, Jun; Kajino, Toshitaka

doi:10.1088/0004-637x/814/1/41

Cited by 117 publications

(136 citation statements)

References 147 publications

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“…Eichler et al 1989;Freiburghaus et al 1999;Wanajo et al 2014;Rosswog 2015;Just et al 2015;Hirai et al 2015;Wu et al 2016;Beniamini et al 2016b). These elements were previously thought to be synthesized primarily in SNe.…”

Section: Heavy R-process Elementsmentioning

confidence: 99%

Formation of Double Neutron Star Systems

Tauris

Krämer

Freire

et al. 2017

ApJ

593

674

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Double neutron star (DNS) systems represent extreme physical objects and the endpoint of an exotic journey of stellar evolution and binary interactions. Large numbers of DNS systems and their mergers are anticipated to be discovered using the Square-Kilometre-Array searching for radio pulsars and high-frequency gravitational wave detectors (LIGO/VIRGO), respectively. Here we discuss all key properties of DNS systems, as well as selection effects, and combine the latest observational data with new theoretical progress on various physical processes with the aim of advancing our knowledge on their formation. We examine key interactions of their progenitor systems and evaluate their accretion history during the high-mass X-ray binary stage, the common envelope phase and the subsequent Case BB mass transfer, and argue that the first-formed NSs have accreted at most ∼ 0.02 M ⊙ . We investigate DNS masses, spins and velocities, and in particular correlations between spin period, orbital period and eccentricity. Numerous Monte Carlo simulations of the second supernova (SN) events are performed to extrapolate pre-SN stellar properties and probe the explosions. All known close-orbit DNS systems are consistent with ultra-stripped exploding stars. Although their resulting NS kicks are often small, we demonstrate a large spread in kick magnitudes which may, in general, depend on the past interaction history of the exploding star and thus correlate with the NS mass. We analyze and discuss NS kick directions based on our SN simulations. Finally, we discuss the terminal evolution of close-orbit DNS systems until they merge and possibly produce a short γ-ray burst.

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Section: Heavy R-process Elementsmentioning

confidence: 99%

Formation of Double Neutron Star Systems

Tauris

Krämer

Freire

et al. 2017

ApJ

593

674

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“…1999; Argast et al 2004;Hirai et al 2015), possibly followed by a so-called "kilonova" (e.g., Metzger et al 2010;Barnes & Kasen 2013;Tanaka & Hotokezaka 2013). However, to produce a double NS system a massive binary must survive two SN explosions.…”

Section: Introductionmentioning

confidence: 99%

Light-curve and spectral properties of ultrastripped core-collapse supernovae leading to binary neutron stars

Moriya

Mazzali

Tominaga

et al. 2016

Mon. Not. R. Astron. Soc.

103

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We investigate light-curve and spectral properties of ultra-stripped core-collapse supernovae. Ultra-stripped supernovae are the explosions of heavily stripped massive stars which lost their envelopes via binary interactions with a compact companion star. They eject only ∼ 0.1 M ⊙ and may be the main way to form double neutronstar systems which eventually merge emitting strong gravitational waves. We follow the evolution of an ultra-stripped supernova progenitor until iron core collapse and perform explosive nucleosynthesis calculations. We then synthesize light curves and spectra of ultra-stripped supernovae using the nucleosynthesis results and present their expected properties. Ultra-stripped supernovae synthesize ∼ 0.01 M ⊙ of radioactive 56 Ni, and their typical peak luminosity is around 10 42 erg s −1 or −16 mag. Their typical rise time is 5 − 10 days. Comparing synthesized and observed spectra, we find that SN 2005ek, some of the so-called calcium-rich gap transients, and SN 2010X may be related to ultra-stripped supernovae. If these supernovae are actually ultra-stripped supernovae, their event rate is expected to be about 1 per cent of core-collapse supernovae. Comparing the double neutron-star merger rate obtained by future gravitational-wave observations and the ultra-stripped supernova rate obtained by optical transient surveys identified with our synthesized light-curve and spectral models, we will be able to judge whether ultra-stripped supernovae are actually a major contributor to the binary neutron star population and provide constraints on binary stellar evolution.

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“…On the other hand, outflows remove metals from galaxies and tend to slow down the growth of their metal content at later time. These ingredients are usually included in the simulation of dwarf galaxies, but with different levels of complexity and different numerical methods, including one-zone models (e.g., Carigi et al 2002;Lanfranchi & Matteucci 2003, 2004Fenner et al 2006;Gibson 2007;Lanfranchi & Matteucci 2010;Lanfranchi et al 2006;Vincenzo et al 2014;Homma et al 2015;Kobayashi et al 2015;Ural et al 2015a), semi-analytical models (e.g., Romano & Starkenburg 2013;Romano et al 2015), and hydrodynamical simulations (e.g., Kawata et al 2006;Marcolini et al 2008;Revaz et al 2009;Pilkington et al 2012;Revaz & Jablonka 2012;Hirai et al 2015;Revaz et al 2016).…”

mentioning

confidence: 99%

The Impact of Modeling Assumptions in Galactic Chemical Evolution Models

Côté

O’Shea

Ritter

et al. 2017

ApJ

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We use the OMEGA galactic chemical evolution code to investigate how the assumptions used for the treatment of galactic inflows and outflows impact numerical predictions. The goal is to determine how our capacity to reproduce the chemical evolution trends of a galaxy is affected by the choice of implementation used to include those physical processes. In pursuit of this goal, we experiment with three different prescriptions for galactic inflows and outflows and use OMEGA within a Markov Chain Monte Carlo code to recover the set of input parameters that best reproduces the chemical evolution of nine elements in the dwarf spheroidal galaxy Sculptor. This provides a consistent framework for comparing the best-fit solutions generated by our different models. Despite their different degrees of intended physical realism, we found that all three prescriptions can reproduce in an almost identical way the stellar abundance trends observed in Sculptor. This result supports the similar conclusions originally claimed by Romano & Starkenburg (2013) for Sculptor. While the three models have the same capacity to fit the data, the best values recovered for the parameters controlling the number of Type Ia supernovae and the strength of galactic outflows, are substantially different and in fact mutually exclusive from one model to another. For the purpose of understanding how a galaxy evolves, we conclude that only reproducing the evolution of a limited number of elements is insufficient and can lead to misleading conclusions. More elements or additional constraints such as the galaxy's star formation efficiency and the gas fraction are needed in order to break the degeneracy between the different modeling assumptions. Our results show that the successes and failures of chemical evolution models are predominantly driven by the input stellar yields, rather than by the complexity of the galaxy model itself. Simple models such as OMEGA are therefore sufficient to test and validate stellar yields. OMEGA is part of the NuGrid chemical evolution package and is publicly available online at http://nugrid.github.io/NuPyCEE.

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ENRICHMENT OFr-PROCESS ELEMENTS IN DWARF SPHEROIDAL GALAXIES IN CHEMO-DYNAMICAL EVOLUTION MODEL

Cited by 117 publications

References 147 publications

Formation of Double Neutron Star Systems

Formation of Double Neutron Star Systems

Light-curve and spectral properties of ultrastripped core-collapse supernovae leading to binary neutron stars

The Impact of Modeling Assumptions in Galactic Chemical Evolution Models

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