scholarly journals The role of faint population III supernovae in forming CEMP stars in ultra-faint dwarf galaxies

2021 ◽  
Author(s):  
Myoungwon Jeon ◽  
Volker Bromm ◽  
Gurtina Besla ◽  
Jinmi Yoon ◽  
Yumi Choi
Keyword(s):  
Milky Way ◽  
Dwarf Galaxies ◽  
Mass Resolution ◽  
Explosion Energy ◽  
High Carbon ◽  
Cosmological Simulations ◽  
Carbon Abundance ◽  
The Absolute ◽  
Zoom In

Abstract CEMP-no stars, a subset of carbon enhanced metal poor (CEMP) stars ($\rm [C/Fe]\ge 0.7$ and $\rm [Fe/H]\lesssim -1$) have been discovered in ultra-faint dwarf (UFD) galaxies, with Mvir ≈ 108 M⊙ and M* ≈ 103 − 104 M⊙ at z = 0, as well as in the halo of the Milky Way (MW). These CEMP-no stars are local fossils that may reflect the properties of the first (Pop III) and second (Pop II) generation of stars. However, cosmological simulations have struggled to reproduce the observed level of carbon enhancement of the known CEMP-no stars. Here we present new cosmological hydrodynamic zoom-in simulations of isolated UFDs that achieve a gas mass resolution of mgas ≈ 60 M⊙. We include enrichment from Pop III faint supernovae (SNe), with ESN = 0.6 × 1051 erg, to understand the origin of CEMP-no stars. We confirm that Pop III and Pop II stars are mainly responsible for the formation of CEMP and C-normal stars respectively. New to this study, we find that a majority of CEMP-no stars in the observed UFDs and the MW halo can be explained by Pop III SNe with normal explosion energy (ESN = 1.2 × 1051 erg) and Pop II enrichment, but faint SNe might also be needed to produce CEMP-no stars with $\rm [C/Fe]\gtrsim 2$, corresponding to the absolute carbon abundance of $\rm A(C)\gtrsim 6.0$. Furthermore, we find that while we create CEMP-no stars with high carbon ratio $\rm [C/Fe]\approx 3-4$, by adopting faint SNe, it is still challenging to reproduce CEMP-no stars with extreme level of carbon abundance of $\rm A(C)\approx 7.0-7.5$, observed both in the MW halo and UFDs.

scholarly journals Star formation histories of dwarf galaxies in the FIRE simulations: dependence on mass and Local Group environment

2019 ◽  
Vol 489 (4) ◽  
pp. 4574-4588 ◽  
Author(s):  
Shea Garrison-Kimmel ◽  
Andrew Wetzel ◽  
Philip F Hopkins ◽  
Robyn Sanderson ◽  
Kareem El-Badry ◽  
...  
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Near Field ◽  
Stellar Mass ◽  
Group Environment ◽  
Zoom In ◽  
The Individual ◽  
Star Formation Histories

ABSTRACT We study star formation histories (SFHs) of 500 dwarf galaxies (stellar mass $M_\ast =10^5\!-\!10^9\, \rm {M}_\odot$) from FIRE-2 cosmological zoom-in simulations. We compare dwarfs around individual Milky Way (MW)-mass galaxies, dwarfs in Local Group (LG)-like environments, and true field (i.e. isolated) dwarf galaxies. We reproduce observed trends wherein higher mass dwarfs quench later (if at all), regardless of environment. We also identify differences between the environments, both in terms of ‘satellite versus central’ and ‘LG versus individual MW versus isolated dwarf central.’ Around the individual MW-mass hosts, we recover the result expected from environmental quenching: central galaxies in the ‘near field’ have more extended SFHs than their satellite counterparts, with the former more closely resemble isolated (true field) dwarfs (though near-field centrals are still somewhat earlier forming). However, this difference is muted in the LG-like environments, where both near-field centrals and satellites have similar SFHs, which resemble satellites of single MW-mass hosts. This distinction is strongest for M* = 106–$10^7\, \rm {M}_\odot$ but exists at other masses. Our results suggest that the paired halo nature of the LG may regulate star formation in dwarf galaxies even beyond the virial radii of the MW and Andromeda. Caution is needed when comparing zoom-in simulations targeting isolated dwarf galaxies against observed dwarf galaxies in the LG.

Transisi Kepemimpinan Dalam Alkitab

2016 ◽  
Vol 1 (1) ◽  
pp. 16-38
Author(s):  
Jonathan Octavianus
Keyword(s):  
New Testament ◽  
Old Testament ◽  
Jesus Christ ◽  
Transition Time ◽  
People Of God ◽  
The Absolute

As every epoch there are there a transition time, on Old Testament like Moses with Joshua, Joshua selected by God an supported fully by Moses, Conversely Moses have liberally to be changed. Like Elijah to Elisha too.Pattern on New Testament there are an examples of transition time too, like Jesus Christ to His Disciples, an transition from Paul to his successor Timothy. This is a heart and soul a big leader, and shall all leadership owners shepherd in church, Christian institution, etc.Which most be remembered in transition of leadership, that people of God leadership, about who will lead, who continue leadership, like a principle in biblical, hence a role of God, is determinant an anoint man which be selected the absolute God choice and constitute all other, but a succession router leader is which have been selected His own. An can be anointed in front of believers.

scholarly journals The role of mergers and interactions in driving the evolution of dwarf galaxies over cosmic time

2020 ◽  
Vol 500 (4) ◽  
pp. 4937-4957 ◽  
Author(s):  
G Martin ◽  
R A Jackson ◽  
S Kaviraj ◽  
H Choi ◽  
J E G Devriendt ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Large Fraction ◽  
Structural Evolution ◽  
Cosmic Time ◽  
Stellar Mass ◽  
High Mass ◽  
Key Drivers ◽  
Mass Assembly

ABSTRACT Dwarf galaxies (M⋆ < 109 M⊙) are key drivers of mass assembly in high-mass galaxies, but relatively little is understood about the assembly of dwarf galaxies themselves. Using the NewHorizon cosmological simulation (∼40 pc spatial resolution), we investigate how mergers and fly-bys drive the mass assembly and structural evolution of around 1000 field and group dwarfs up to z = 0.5. We find that, while dwarf galaxies often exhibit disturbed morphologies (5 and 20 per cent are disturbed at z = 1 and z = 3 respectively), only a small proportion of the morphological disturbances seen in dwarf galaxies are driven by mergers at any redshift (for 109 M⊙, mergers drive under 20 per cent morphological disturbances). They are instead primarily the result of interactions that do not end in a merger (e.g. fly-bys). Given the large fraction of apparently morphologically disturbed dwarf galaxies which are not, in fact, merging, this finding is particularly important to future studies identifying dwarf mergers and post-mergers morphologically at intermediate and high redshifts. Dwarfs typically undergo one major and one minor merger between z = 5 and z = 0.5, accounting for 10 per cent of their total stellar mass. Mergers can also drive moderate star formation enhancements at lower redshifts (3 or 4 times at z = 1), but this accounts for only a few per cent of stellar mass in the dwarf regime given their infrequency. Non-merger interactions drive significantly smaller star formation enhancements (around two times), but their preponderance relative to mergers means they account for around 10 per cent of stellar mass formed in the dwarf regime.

scholarly journals The Absolute as the Meeting Point Between Speculation and Fiction

2020 ◽  
Vol 3 (1) ◽  
pp. 349-357 ◽  
Author(s):  
Daina Habdankaitė
Keyword(s):  
Science Fiction ◽  
Significant Role ◽  
Meeting Point ◽  
Weird Fiction ◽  
Weak Points ◽  
The Absolute

AbstractThe article investigates Meillassoux’s notion of the absolute in relationship with the Kantian and Hegelian philosophical systems. The absolute, as independent of subjective consciousness, is showcased as the meeting point of speculation and fiction. By looking into Meillassoux’s notions of speculation and some works of weird fiction, it is argued that the significant role of imagination as well as a deferred temporality is what facilitates the discussion of both speculation and fiction as faculties able to transcend the limitations that are projected by the correlationist mind. Through a reading of Lovecraftian fiction, both the strong and weak points of Meillassoux’s argumentation in After Finitude and Science Fiction and Extro-Science Fiction are identified, proving the latter to be a less successful way of grasping the chaotic real.

Unraveling the Role of Zinc on Bimetallic Fe5C2–ZnO Catalysts for Highly Selective Carbon Dioxide Hydrogenation to High Carbon α-Olefins

ACS Catalysis ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 2121-2133
Author(s):  
Chao Zhang ◽  
Chenxi Cao ◽  
Yulong Zhang ◽  
Xianglin Liu ◽  
Jing Xu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
High Carbon ◽  
Carbon Dioxide Hydrogenation

scholarly journals The mass of the Milky Way out to 100 kpc using halo stars

2020 ◽  
Author(s):  
Alis J Deason ◽  
Denis Erkal ◽  
Vasily Belokurov ◽  
Azadeh Fattahi ◽  
Facundo A Gómez ◽  
...  
Keyword(s):  
Distribution Function ◽  
Mass Concentration ◽  
Milky Way ◽  
Function Analysis ◽  
Large Magellanic Cloud ◽  
Systematic Bias ◽  
Cosmological Simulations ◽  
Halo Stars ◽  
Systematic Effects ◽  
Mass Estimate

Abstract We use a distribution function analysis to estimate the mass of the Milky Way out to 100 kpc using a large sample of halo stars. These stars are compiled from the literature, and the vast majority ($\sim \! 98\%$) have 6D phase-space information. We pay particular attention to systematic effects, such as the dynamical influence of the Large Magellanic Cloud (LMC), and the effect of unrelaxed substructure. The LMC biases the (pre-LMC infall) halo mass estimates towards higher values, while realistic stellar halos from cosmological simulations tend to underestimate the true halo mass. After applying our method to the Milky Way data we find a mass within 100 kpc of M( < 100kpc) = 6.07 ± 0.29(stat.) ± 1.21(sys.) × 1011M⊙. For this estimate, we have approximately corrected for the reflex motion induced by the LMC using the Erkal et al. model, which assumes a rigid potential for the LMC and MW. Furthermore, stars that likely belong to the Sagittarius stream are removed, and we include a 5% systematic bias, and a 20% systematic uncertainty based on our tests with cosmological simulations. Assuming the mass-concentration relation for Navarro-Frenk-White haloes, our mass estimate favours a total (pre-LMC infall) Milky Way mass of M200c = 1.01 ± 0.24 × 1012M⊙, or (post-LMC infall) mass of M200c = 1.16 ± 0.24 × 1012 M⊙ when a 1.5 × 1011M⊙ mass of a rigid LMC is included.

Role of Barium(II) in the Determination of the Absolute Configuration of Chiral Amines by1H NMR Spectroscopy

2006 ◽  
Vol 71 (3) ◽  
pp. 1119-1130 ◽  
Author(s):  
Rosa García ◽  
José M. Seco ◽  
Saulo A. Vázquez ◽  
Emilio Quiñoá ◽  
Ricardo Riguera
Keyword(s):  
Nmr Spectroscopy ◽  
Absolute Configuration ◽  
Chiral Amines ◽  
The Absolute

Disk Heating: Comparing the Milky Way with Cosmological Simulations

2010 ◽  
Author(s):  
Elisa L. House ◽  
Chris B. Brook ◽  
Brad K. Gibson ◽  
Victor P. Debattista ◽  
C. C. Popescu
Keyword(s):  
Milky Way ◽  
Cosmological Simulations

scholarly journals Gaia DR2 proper motions of dwarf galaxies within 420 kpc

2018 ◽  
Vol 619 ◽  
pp. A103 ◽  
Author(s):  
T. K. Fritz ◽  
G. Battaglia ◽  
M. S. Pawlowski ◽  
N. Kallivayalil ◽  
R. van der Marel ◽  
...  
Keyword(s):  
Milky Way ◽  
Dwarf Galaxies ◽  
High Mass ◽  
Proper Motions ◽  
Proper Understanding ◽  
Satellite Problem ◽  
Cosmological Context ◽  
Good Consistency ◽  
Gaia Dr2 ◽  
Limited Accuracy

A proper understanding of the Milky Way (MW) dwarf galaxies in a cosmological context requires knowledge of their 3D velocities and orbits. However, proper motion (PM) measurements have generally been of limited accuracy and are available only for more massive dwarfs. We therefore present a new study of the kinematics of the MW dwarf galaxies. We use the Gaia DR2 for those dwarfs that have been spectroscopically observed in the literature. We derive systemic PMs for 39 galaxies and galaxy candidates out to 420 kpc, and generally find good consistency for the subset with measurements available from other studies. We derive the implied Galactocentric velocities, and calculate orbits in canonical MW halo potentials of low (0.8 × 1012 M⊙) and high mass (1.6 × 1012 M⊙). Comparison of the distributions of orbital apocenters and 3D velocities to the halo virial radius and escape velocity, respectively, suggests that the satellite kinematics are best explained in the high-mass halo. Tuc III, Crater II, and additional candidates have orbital pericenters small enough to imply significant tidal influences. Relevant to the missing satellite problem, the fact that fewer galaxies are observed to be near apocenter than near pericenter implies that there must be a population of distant dwarf galaxies yet to be discovered. Of the 39 dwarfs: 12 have orbital poles that do not align with the MW plane of satellites (given reasonable assumptions about its intrinsic thickness); 10 have insufficient PM accuracy to establish whether they align; and 17 satellites align, of which 11 are co-orbiting and (somewhat surprisingly, in view of prior knowledge) 6 are counter-orbiting. Group infall might have contributed to this, but no definitive association is found for the members of the Crater-Leo group.

scholarly journals Introspective cosmopolitanism: The family in the Greek Weird Wave

2020 ◽  
Vol 6 (1) ◽  
pp. 3-27 ◽  
Author(s):  
Dimitris Eleftheriotis
Keyword(s):  
Conceptual Model ◽  
Theoretical Work ◽  
Critical Discourse ◽  
Greek Crisis ◽  
The Family ◽  
The Absolute ◽  
Critical Interpretation ◽  
Self Examination

This article reframes the critical discourse around the ‘Greek Weird Wave’ using an approach informed by theoretical work on cosmopolitanism. Focussing on Yorgos Lanthimos’s Dogtooth (2009) and Athena-Rachel Tsangari’s Attenberg (2010), the critical interpretation of the role of the family is radically rethought. I argue that the privileging of allegorical readings of the family in the Weird Wave films constitutes a form of critical denial of the deeply problematic and specifically Greek ways in which the family (dys)functions. I challenge the absolute and exclusive power that the Greek ‘crisis’ holds over interpretations and evaluations of Weird Wave films, which discursively displaces the problems of the family to broader sociopolitical frameworks. In reclaiming the importance of literal readings of the films, I reposition them as manifestations of a specific cosmopolitan disposition, that of introspection, a process of self-examination that overcomes denial. In turn, the critical reframing of the films outlines the contours of a complex agonistics of introspective cosmopolitanism, an inward investigative disposition that is dialectically linked to cosmopolitan positioning. Jean François Lyotard’s 1989 theorization of the oikos (home/house) provides a conceptual model for understanding the family (oikogeneia), which, in its Greek specificities, is central to the films under discussion.

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