scholarly journals Halo Mass-concentration Relation at the High-mass End

2021 ◽  
Vol 922 (2) ◽  
pp. 162
Author(s):  
Weiwei Xu ◽  
Huanyuan Shan ◽  
Ran Li ◽  
Chunxiang Wang ◽  
Linhua Jiang ◽  
...  
Keyword(s):  
Mass Concentration ◽  
Cluster Formation ◽  
High Mass ◽  
Dark Matter Halos ◽  
Power Law Model ◽  
M 10 ◽  
The Galaxy ◽  
History Of ◽  
Halo Masses ◽  
Massive Cluster

Abstract The concentration–mass (c–M) relation encodes key information about the assembly history of dark matter halos. However, its behavior at the high mass end has not been measured precisely in observations yet. In this paper, we report the measurement of the halo c–M relation with the galaxy–galaxy lensing method, using the shear catalog of the Dark Energy Camera Legacy Survey (DECaLS) Data Release 8, which covers a sky area of 9500 deg2. The foreground lenses are selected from the redMaPPer, LOWZ, and CMASS catalogs, with halo masses ranging from 1013 to 1015 M ⊙ and redshifts ranging from z = 0.08 to z = 0.65. We find that the concentration decreases with the halo mass from 1013 to 1014 M ⊙, but shows a trend of upturn after the pivot point of ∼1014 M ⊙. We fit the measured c–M relation with the concentration model c ( M ) = C 0 M 10 12 M ⊙ / h − γ 1 + M M 0 0.4 , and we get the values (C 0, γ, log10(M 0)) = (5.119−0.185 0.183, 0.205 − 0.010 0.010 , 14.083 − 0.133 0.130 ) and ( 4.875 − 0.208 0.209 , 0.221 − 0.010 0.010 , 13.750 − 0.141 0.142 ) for halos with 0.08 ≤ z < 0.35 and 0.35 ≤ z < 0.65, respectively. We also show that the model including an upturn is favored over a simple power-law model. Our measurement provides important information for the recent argument over the massive cluster formation process.

scholarly journals The globular cluster system of the Auriga simulations

2020 ◽  
Vol 496 (1) ◽  
pp. 638-648 ◽  
Author(s):  
Timo L R Halbesma ◽  
Robert J J Grand ◽  
Facundo A Gómez ◽  
Federico Marinacci ◽  
Rüdiger Pakmor ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Milky Way ◽  
Cluster Formation ◽  
Solar Radius ◽  
High Mass ◽  
Formation Model ◽  
The Galaxy ◽  
High Mass Loss ◽  
Globular Cluster System ◽  
Varying Mass

ABSTRACT We investigate whether the galaxy and star formation model used for the Auriga simulations can produce a realistic globular cluster (GC) population. We compare statistics of GC candidate star particles in the Auriga haloes with catalogues of the Milky Way (MW) and Andromeda (M31) GC populations. We find that the Auriga simulations do produce sufficient stellar mass for GC candidates at radii and metallicities that are typical for the MW GC system (GCS). We also find varying mass ratios of the simulated GC candidates relative to the observed mass in the MW and M31 GCSs for different bins of galactocentric radius metallicity (rgal–[Fe/H]). Overall, the Auriga simulations produce GC candidates with higher metallicities than the MW and M31 GCS and they are found at larger radii than observed. The Auriga simulations would require bound cluster formation efficiencies higher than 10 per cent for the metal-poor GC candidates, and those within the Solar radius should experience negligible destruction rates to be consistent with observations. GC candidates in the outer halo, on the other hand, should either have low formation efficiencies, or experience high mass-loss for the Auriga simulations to produce a GCS that is consistent with that of the MW or M31. Finally, the scatter in the metallicity as well as in the radial distribution between different Auriga runs is considerably smaller than the differences between that of the MW and M31 GCSs. The Auriga model is unlikely to give rise to a GCS that can be consistent with both galaxies.

scholarly journals High-Mass Star and Massive Cluster Formation in the Milky Way

2018 ◽  
Vol 56 (1) ◽  
pp. 41-82 ◽  
Author(s):  
Frédérique Motte ◽  
Sylvain Bontemps ◽  
Fabien Louvet
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Galactic Plane ◽  
Cluster Formation ◽  
Theoretical Models ◽  
High Mass ◽  
High Angular Resolution ◽  
Mass Star ◽  
Star Forming ◽  
Massive Cluster

This review examines the state-of-the-art knowledge of high-mass star and massive cluster formation, gained from ambitious observational surveys, which acknowledges the multiscale characteristics of these processes. After a brief overview of theoretical models and main open issues, we present observational searches for the evolutionary phases of high-mass star formation, first among high-luminosity sources and more recently among young massive protostars and the elusive high-mass prestellar cores. We then introduce the most likely evolutionary scenario for high-mass star formation, which emphasizes the link of high-mass star formation to massive cloud and cluster formation. Finally, we introduce the first attempts to search for variations of the star-formation activity and cluster formation in molecular cloud complexes in the most extreme star-forming sites and across the Milky Way. The combination of Galactic plane surveys and high–angular resolution images with submillimeter facilities such as Atacama Large Millimeter Array (ALMA) are prerequisites to make significant progress in the forthcoming decade.

scholarly journals Peak star formation efficiency and no missing baryons in massive spirals

2019 ◽  
Vol 626 ◽  
pp. A56 ◽  
Author(s):  
Lorenzo Posti ◽  
Filippo Fraternali ◽  
Antonino Marasco
Keyword(s):  
Star Formation ◽  
High Mass ◽  
Dark Matter Halos ◽  
Rotation Curves ◽  
Nearby Star ◽  
Star Forming ◽  
Hot Gas ◽  
Halo Masses ◽  
Formation Efficiency ◽  
Increasing Function

It is commonly believed that galaxies use, throughout Hubble time, a very small fraction of the baryons associated with their dark matter halos to form stars. This so-called low star formation efficiency f⋆ ≡ M⋆/fbMhalo, where fb ≡ Ωb/Ωc is the cosmological baryon fraction, is expected to reach its peak at nearly L* (at efficiency ≈20%) and decline steeply at lower and higher masses. We have tested this using a sample of nearby star-forming galaxies, from dwarfs (M⋆ ≃ 107 M⊙) to high-mass spirals (M⋆ ≃ 1011 M⊙) with HI rotation curves and 3.6 μm photometry. We fit the observed rotation curves with a Bayesian approach by varying three parameters, stellar mass-to-light ratio Υ⋆, halo concentration c, and mass Mhalo. We found two surprising results: (1) the star formation efficiency is a monotonically increasing function of M⋆ with no sign of a decline at high masses, and (2) the most massive spirals (M⋆ ≃ 1−3 × 1011 M⊙) have f⋆ ≈ 0.3−1, i.e. they have turned nearly all the baryons associated with their halos into stars. These results imply that the most efficient galaxies at forming stars are massive spirals (not L* galaxies); they reach nearly 100% efficiency, and thus once both their cold and hot gas is considered in the baryon budget, they have virtually no missing baryons. Moreover, there is no evidence of mass quenching of the star formation occurring in galaxies up to halo masses of a few × 1012 M⊙.

scholarly journals Cluster formation induced by a cloud–cloud collision in [DBS2003]179

2020 ◽  
Author(s):  
Sho Kuwahara ◽  
Kazufumi Torii ◽  
Norikazu Mizuno ◽  
Shinji Fujita ◽  
Mikito Kohno ◽  
...  
Keyword(s):  
Near Infrared ◽  
Cluster Formation ◽  
Dust Emission ◽  
Star Clusters ◽  
High Ratio ◽  
Star Cluster ◽  
High Mass ◽  
Mass Star ◽  
The Galaxy ◽  
Super Star Clusters

Abstract [DBS2003]179 is a super star cluster in the Galaxy discovered in deep near-infrared observations. We carried out CO $J$ = 1–0 and $J$ = 3–2 observations of the region of [DBS2003]179 with NANTEN2, ASTE, and the Mopra 22 m telescope. We identified and mapped two molecular clouds that are likely to be associated with the cluster. This association is supported by the spatial correlation with the corresponding 8$\, \mu$m Spitzer image and by a high ratio of the two transitions of $^{12}$CO($J$ = 3–2 and $J$ = 1–0). The two clouds show complementary distributions in space, and bridging features connect them in velocity. We hypothesize that the two clouds collided with each other 1–2 Myr ago and that the collision compressed the interfacial layer, triggering the formation of the cluster. This offers an additional piece of evidence for a super star cluster formed by a cloud–cloud collision, alongside the four super star clusters Westerlund$\:2$, NGC 3603, RCW 38, and R 136. These findings indicate that the known super star clusters with closely associated dust emission were formed by cloud–cloud collisions, lending support to the important role of cloud–cloud collisions in high-mass star formation.

scholarly journals SDSS-IV MaNGA: the ‘G-dwarf problem’ revisited

2021 ◽  
Vol 502 (1) ◽  
pp. L95-L98
Author(s):  
Michael J Greener ◽  
Michael Merrifield ◽  
Alfonso Aragón-Salamanca ◽  
Thomas Peterken ◽  
Brett Andrews ◽  
...  
Keyword(s):  
Milky Way ◽  
High Mass ◽  
Dwarf Stars ◽  
The Galaxy ◽  
Star Formation In Galaxies ◽  
History Of ◽  
Low Metallicity ◽  
Low Mass ◽  
Gas Accretion ◽  
Made In

ABSTRACT The levels of heavy elements in stars are the product of enhancement by previous stellar generations, and the distribution of this metallicity among the population contains clues to the process by which a galaxy formed. Most famously, the ‘G-dwarf problem’ highlighted the small number of low-metallicity G-dwarf stars in the Milky Way, which is inconsistent with the simplest picture of a galaxy formed from a ‘closed box’ of gas. It can be resolved by treating the Galaxy as an open system that accretes gas throughout its life. This observation has classically only been made in the Milky Way, but the availability of high-quality spectral data from SDSS-IV MaNGA and the development of new analysis techniques mean that we can now make equivalent measurements for a large sample of spiral galaxies. Our analysis shows that high-mass spirals generically show a similar deficit of low-metallicity stars, implying that the Milky Way’s history of gas accretion is common. By contrast, low-mass spirals show little sign of a G-dwarf problem, presenting the metallicity distribution that would be expected if such systems evolved as pretty much closed boxes. This distinction can be understood from the differing timescales for star formation in galaxies of differing masses.

scholarly journals Formation of the super star cluster RCW 38 triggered by cloud-cloud collision

2015 ◽  
Vol 12 (S316) ◽  
pp. 208-213
Author(s):  
Yasuo Fukui
Keyword(s):  
Molecular Clouds ◽  
Column Density ◽  
Cluster Formation ◽  
Star Cluster ◽  
Cluster Center ◽  
Molecular Gas ◽  
Velocity Difference ◽  
The Galaxy ◽  
Massive Cluster ◽  
High Column

AbstractRCW 38 is the youngest super star cluster in the Galaxy and is located at a distance of 1.7 kpc. Molecular observations revealed that the cluster is associated with two molecular clouds having velocity difference of 12 km s−1. We interpret that the two clouds are colliding with each other and the collision triggered the cluster formation. The natal molecular gas still survives within ~ 0.5 pc of the central O stars which have an age of 0.1 Myrs as inferred from the collision morphology. We suggest that the high column density of one of the clouds 1023 cm−2 enabled formation of ~ 20 O stars in the cluster center and discuss the implications on massive cluster formation.

Stellar populations and ionised gas in central spheroidal galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 469-472
Author(s):  
Vanessa Lorenzoni ◽  
Sandro B. Rembold
Keyword(s):  
Stellar Population ◽  
Synthesis Method ◽  
Galactic Nuclei ◽  
Stellar Populations ◽  
High Mass ◽  
Population Synthesis ◽  
The Galaxy ◽  
History Of ◽  
Low Mass ◽  
Spheroidal Galaxies

We investigate the stellar populations and ionised gas properties of a sample of central spheroidal galaxies in order to better constrain their history of star formation and gas excitation mechanism. We select galaxies from Spheroids Panchromatic Investigation in Different Environmental Regions (SPIDER) catalogue and separate these galaxies in different regimes of halo and galaxy mass. To characterise the stellar population properties of these galaxies we use the stellar population synthesis method with the Starlight code, and the presence of ionised gas is identified by measurements of the Hα equivalent width. We analyse how these properties behave as a function of the galaxy stellar mass and the parent halo mass. A trend is observed in the sense of increased ionised gas emission for low-mass centrals in high-mass halos. We interpret this trend in a scenario of intracluster medium (ICM) cooling versus active galactic nuclei (AGN) feedback in a Bondi accretion context.

scholarly journals Cloud–cloud collisions and triggered star formation

2020 ◽  
Author(s):  
Yasuo Fukui ◽  
Asao Habe ◽  
Tsuyoshi Inoue ◽  
Rei Enokiya ◽  
Kengo Tachihara
Keyword(s):  
Star Formation ◽  
Cluster Formation ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Ngc 6334 ◽  
Almost All ◽  
Massive Cluster

Abstract Star formation is a fundamental process for galactic evolution. One issue over the last several decades has been determining whether star formation is induced by external triggers or self-regulated in a closed system. The role of an external trigger, which can effectively collect mass in a small volume, has attracted particular attention in connection with the formation of massive stellar clusters, which in extreme cases may lead to starbursts. Recent observations have revealed massive cluster formation triggered by cloud–cloud collisions in nearby interacting galaxies, including the Magellanic system and the Antennae Galaxies as well as almost all well-known high-mass star-forming regions in the Milky Way, such as RCW 120, M 20, M 42, NGC 6334, etc. Theoretical efforts are going into the foundation for the mass compression that causes massive cluster/star formation. Here, we review the recent progress on cloud–cloud collisions and the triggered star-cluster formation, and discuss future prospects for this area of study.

The Tempo and mode(S) of Prebiotic Evolution

1997 ◽  
Vol 161 ◽  
pp. 419-429 ◽  
Author(s):  
Antonio Lazcano
Keyword(s):  
Origin Of Life ◽  
Organic Compounds ◽  
Biological Evolution ◽  
Current Evidence ◽  
Early Diversification ◽  
Time Period ◽  
The Galaxy ◽  
History Of ◽  
Widespread Phenomenon ◽  
The Origin Of Life

AbstractDifferent current ideas on the origin of life are critically examined. Comparison of the now fashionable FeS/H2S pyrite-based autotrophic theory of the origin of life with the heterotrophic viewpoint suggest that the later is still the most fertile explanation for the emergence of life. However, the theory of chemical evolution and heterotrophic origins of life requires major updating, which should include the abandonment of the idea that the appearance of life was a slow process involving billions of years. Stability of organic compounds and the genetics of bacteria suggest that the origin and early diversification of life took place in a time period of the order of 10 million years. Current evidence suggest that the abiotic synthesis of organic compounds may be a widespread phenomenon in the Galaxy and may have a deterministic nature. However, the history of the biosphere does not exhibits any obvious trend towards greater complexity or «higher» forms of life. Therefore, the role of contingency in biological evolution should not be understimated in the discussions of the possibilities of life in the Universe.

scholarly journals Evidence for multiple introductions of an invasive wild bee species currently under rapid range expansion in Europe

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Julia Lanner ◽  
Fabian Gstöttenmayer ◽  
Manuel Curto ◽  
Benoît Geslin ◽  
Katharina Huchler ◽  
...  
Keyword(s):  
Cluster Formation ◽  
Invasion History ◽  
European Continent ◽  
Multiple Introductions ◽  
Wild Bee ◽  
Invasion Stage ◽  
Middle Europe ◽  
History Of ◽  
Genetic Clusters ◽  
Colonization Dynamics

Abstract Background Invasive species are increasingly driving biodiversity decline, and knowledge of colonization dynamics, including both drivers and dispersal modes, are important to prevent future invasions. The bee species Megachile sculpturalis (Hymenoptera: Megachilidae), native to East-Asia, was first recognized in Southeast-France in 2008, and has since spread throughout much of Europe. The spread is very fast, and colonization may result from multiple fronts. Result To track the history of this invasion, codominant markers were genotyped using Illumina sequencing and the invasion history and degree of connectivity between populations across the European invasion axis were investigated. Distinctive genetic clusters were detected with east–west differentiations in Middle-Europe. Conclusion We hypothesize that the observed cluster formation resulted from multiple, independent introductions of the species to the European continent. This study draws a first picture of an early invasion stage of this wild bee and forms a foundation for further investigations, including studies of the species in their native Asian range and in the invaded range in North America.

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