scholarly journals Formation sites of Population III star formation: The effects of different levels of rotation and turbulence on the fragmentation behaviour of primordial gas

2020 ◽  
Vol 494 (2) ◽  
pp. 1871-1893 ◽  
Author(s):  
Katharina M J Wollenberg ◽  
Simon C O Glover ◽  
Paul C Clark ◽  
Ralf S Klessen
Keyword(s):  
Star Formation ◽  
Initial Conditions ◽  
Turbulent Energy ◽  
Star Forming ◽  
Wide Range ◽  
Population Iii Stars ◽  
The Individual ◽  
The Masses ◽  
Different Levels ◽  
Population Iii

ABSTRACT We use the moving-mesh code arepo to investigate the effects of different levels of rotation and turbulence on the fragmentation of primordial gas and the formation of Population III stars. We consider nine different combinations of turbulence and rotation and carry out five different realizations of each setup, yielding one of the largest sets of simulations of Population III star formation ever performed. We find that fragmentation in Population III star-forming systems is a highly chaotic process and show that the outcomes of individual realizations of the same initial conditions often vary significantly. However, some general trends are apparent. Increasing the turbulent energy promotes fragmentation, while increasing the rotational energy inhibits fragmentation. Within the ∼1000 yr period that we simulate, runs including turbulence yield flat protostellar mass functions while purely rotational runs show a more top-heavy distribution. The masses of the individual protostars are distributed over a wide range from a few $10^{-3} \, {\rm M_{\odot }}$ to several tens of M⊙. The total mass growth rate of the stellar systems remains high throughout the simulations and depends only weakly on the degree of rotation and turbulence. Mergers between protostars are common, but predictions of the merger fraction are highly sensitive to the criterion used to decide whether two protostars should merge. Previous studies of Population III star formation have often considered only one realization per set of initial conditions. However, our results demonstrate that robust trends can only be reliably identified by considering averages over a larger sample of runs.

scholarly journals Modelling H2 and its effects on star formation using a joint implementation of gadget-3 and KROME

2021 ◽  
Vol 504 (2) ◽  
pp. 2325-2345
Author(s):  
Emanuel Sillero ◽  
Patricia B Tissera ◽  
Diego G Lambas ◽  
Stefano Bovino ◽  
Dominik R Schleicher ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Physical Parameters ◽  
Density Profiles ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Numerical Resolution ◽  
Stellar Radiation ◽  
Wide Range ◽  
The Impact

ABSTRACT We present p-gadget3-k, an updated version of gadget-3, that incorporates the chemistry package krome. p-gadget3-k follows the hydrodynamical and chemical evolution of cosmic structures, incorporating the chemistry and cooling of H2 and metal cooling in non-equilibrium. We performed different runs of the same ICs to assess the impact of various physical parameters and prescriptions, namely gas metallicity, molecular hydrogen formation on dust, star formation recipes including or not H2 dependence, and the effects of numerical resolution. We find that the characteristics of the simulated systems, both globally and at kpc-scales, are in good agreement with several observable properties of molecular gas in star-forming galaxies. The surface density profiles of star formation rate (SFR) and H2 are found to vary with the clumping factor and resolution. In agreement with previous results, the chemical enrichment of the gas component is found to be a key ingredient to model the formation and distribution of H2 as a function of gas density and temperature. A star formation algorithm that takes into account the H2 fraction together with a treatment for the local stellar radiation field improves the agreement with observed H2 abundances over a wide range of gas densities and with the molecular Kennicutt–Schmidt law, implying a more realistic modelling of the star formation process.

scholarly journals Exploration of the high-redshift universe enabled by THESEUS

2021 ◽  
Author(s):  
N. R. Tanvir ◽  
E. Le Floc’h ◽  
L. Christensen ◽  
J. Caruana ◽  
R. Salvaterra ◽  
...  
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
High Redshift ◽  
Formation Rate ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Long Duration ◽  
Absorption Studies ◽  
Population Iii Stars ◽  
High Redshift Universe

AbstractAt peak, long-duration gamma-ray bursts are the most luminous sources of electromagnetic radiation known. Since their progenitors are massive stars, they provide a tracer of star formation and star-forming galaxies over the whole of cosmic history. Their bright power-law afterglows provide ideal backlights for absorption studies of the interstellar and intergalactic medium back to the reionization era. The proposed THESEUS mission is designed to detect large samples of GRBs at z > 6 in the 2030s, at a time when supporting observations with major next generation facilities will be possible, thus enabling a range of transformative science. THESEUS will allow us to explore the faint end of the luminosity function of galaxies and the star formation rate density to high redshifts; constrain the progress of re-ionisation beyond $z\gtrsim 6$ z ≳ 6 ; study in detail early chemical enrichment from stellar explosions, including signatures of Population III stars; and potentially characterize the dark energy equation of state at the highest redshifts.

scholarly journals Clumpy Galaxies in the Early Universe

2006 ◽  
Vol 2 (S235) ◽  
pp. 376-380 ◽  
Author(s):  
Debra Meloy Elmegreen
Keyword(s):  
Star Formation ◽  
Early Universe ◽  
Spiral Galaxies ◽  
Star Forming ◽  
Wide Range ◽  
Thick Disks ◽  
Hubble Ultra Deep Field

AbstractClumpy galaxies are prominent in the early Universe. We present morphological and photometric properties of a wide range of galaxy types and their star-forming clumps in the Hubble Ultra Deep Field. Sizes, scale lengths, and scale heights suggest that galaxies grow by a factor of 2 fromz= 4 to the present, and that thick disks are present in the early Universe. The largest clumps of star formation are 107–109M⊙in different galaxies, much more massive than large star-forming complexes in local galaxies. Dissolved clumps may account for both the exponential disks and the early thick disks of spirals and proto-spiral galaxies.

scholarly journals The masses of Population III stars

1989 ◽  
Vol 239 (2) ◽  
pp. 371-380 ◽  
Author(s):  
J. C. N. de Araujo ◽  
R. Opher
Keyword(s):  
Population Iii Stars ◽  
The Masses ◽  
Population Iii

scholarly journals IRAM and Gaia views of multi-episodic star formation in IC 1396A

2019 ◽  
Vol 622 ◽  
pp. A118 ◽  
Author(s):  
Aurora Sicilia-Aguilar ◽  
Nimesh Patel ◽  
Min Fang ◽  
Veronica Roccatagliata ◽  
Konstantin Getman ◽  
...  
Keyword(s):  
Star Formation ◽  
Column Density ◽  
Velocity Structure ◽  
Initial Conditions ◽  
Carbon Chain ◽  
Star Formation History ◽  
Evolutionary Stage ◽  
Star Forming ◽  
History Of ◽  
Continuum Data

Context. IC 1396A is a cometary globule that contains the Class 0 source IC 1396A-PACS-1, which was discovered with Herschel. Aims. We use IRAM 30m telescope and Gaia DR2 data to explore the star formation history of IC 1396A and investigate the possibilities of triggered star formation. Methods. IRAM and Herschel continuum data were used to obtain dust temperature and column density maps. Heterodyne data reveal the velocity structure of the gas. Gaia DR2 proper motions for the stars complete the kinematics of the region. Results. IC 1396A-PACS-1 presents molecular emission similar to a hot corino with warm carbon chain chemistry due to the UV irradiation. The source is embedded in a dense clump surrounded by gas at velocities that are significantly different from the velocities of the Tr 37 cluster. CN emission reveals photoevaporation, while continuum data and high-density tracers (C18O, HCO+, DCO+, and N2D+) reveal distinct gaseous structures with a range of densities and masses. Conclusions. By combining the velocity, column density, and temperature information and Gaia DR2 kinematics, we confirm that the globule has experienced various episodes of star formation. IC 1396A-PACS-1 is probably the last intermediate-mass protostar that will form within IC 1396A; it shows evidence of being triggered by radiation-driven implosion. Chemical signatures such as CCS place IC 1396A-PACS-1 among the youngest known protostars. Gaia DR2 data reveal velocities in the plane of the sky ~4 km s−1 for IC 1396A with respect to Tr 37. The total velocity difference (8 km s−1) between the Tr 37 cluster and IC 1396A is too small for IC 1396A to have undergone substantial rocket acceleration, which imposes constraints on the distance to the ionizing source in time and the possibilities of triggered star formation. The three stellar populations in the globule reveal that objects located within relatively close distances (<0.5 pc) can be formed in various star-forming episodes within ~1–2 Myr. Once the remaining cloud disperses, we expect substantial differences in evolutionary stage and initial conditions for the resulting objects and their protoplanetary disks, which may affect their evolution. Finally, evidence for short-range feedback from the embedded protostars, and in particular, the A-type star V390 Cep, is also observed.

scholarly journals Properties of ionized outflows in MaNGA DR2 galaxies

2019 ◽  
Vol 486 (1) ◽  
pp. 344-359 ◽  
Author(s):  
Bruno Rodríguez del Pino ◽  
Santiago Arribas ◽  
Javier Piqueras López ◽  
Montserrat Villar-Martín ◽  
Luis Colina
Keyword(s):  
Star Formation ◽  
Emission Region ◽  
Ionization Mechanism ◽  
Host Galaxies ◽  
Star Forming ◽  
Spatially Resolved ◽  
Nearby Galaxies ◽  
Nuclear Regions ◽  
The Individual ◽  
Stellar Masses

ABSTRACT We present the results from a systematic search and characterization of ionized outflows in nearby galaxies using the data from the second Data Release of the Mapping Nearby Galaxies at Arecibo Point Observatory (MaNGA) Survey (DR2; &gt;2700 galaxies, z ≤ 0.015). Using the spatially resolved spectral information provided by the MANGA data, we have identified ∼5200 H α-emitting regions across the galaxies and searched for signatures of ionized outflows. We find evidence for ionized outflows in 105 regions from 103 galaxies, roughly 7 per cent of all the H α-emitting galaxies identified in this work. Most of the outflows are nuclear, with only two cases detected in off-nuclear regions. Our analysis allows us to study ionized outflows in individual regions with star formation rates (SFRs) down to ∼0.01 M⊙ yr−1, extending the ranges probed by previous works. The kinematics of the outflowing gas is strongly linked to the type of ionization mechanism: regions characterized by low-ionization emission region emission (LIER) host the outflows with more extreme kinematics (FWHMbroad ∼ 900 km s−1), followed by those originated in active galactic nuclei (550 km s−1), ‘Intermediate’ (450 km s−1), and star-forming (350 km s−1) regions. Moreover, in most of the outflows we find evidence for gas ionized by shocks. We find a trend for higher outflow kinematics towards larger stellar masses of the host galaxies but no significant variation as a function of star formation properties within the SFR regime we probe (∼0.01–10 M⊙ yr−1). Our results also show that the fraction of outflowing gas that can escape from galaxies decreases towards higher dynamical masses, contributing to the preservation of the mass–metallicity relation by regulating the amount of metals in galaxies. Finally, assuming that the extensions of the outflows are significantly larger than the individual star-forming regions, as found in previous works, our results also support the presence of star formation within ionized outflows, as recently reported by Maiolino et al. (2017) and Gallagher et al. (2018).

Panchromatic study of the first galaxies in cosmological simulations

2019 ◽  
Vol 15 (S341) ◽  
pp. 240-244
Author(s):  
Hidenobu Yajima ◽  
Shohei Arata ◽  
Makito Abe ◽  
Kentaro Nagamine
Keyword(s):  
Star Formation ◽  
Initial Conditions ◽  
High Redshift ◽  
Radiative Properties ◽  
Massive Galaxies ◽  
Star Forming ◽  
Lyman Alpha ◽  
Radiation Properties ◽  
Multi Wavelength ◽  
First Galaxies

AbstractRecent discoveries of high-redshift galaxies have revealed the diversity of their physical properties, from normal star-forming galaxies to starburst galaxies. To understand the properties of these observed galaxies, it is crucial to understand the star formation (SF) history, and the radiation properties associated with the SF activity. Here we present the results of cosmological hydrodynamic simulations with zoom-in initial conditions, and show the formation of the first galaxies and their evolution towards observable galaxies at z = 6. In addition, we show their multi-wavelength radiative properties. We find that star formation occurs intermittently due to supernova (SN) feedback at z > 10, and their radiation properties rapidly change with time. We suggest that the first galaxies are bright at UV wavelengths just after the starburst phase, and become extended Lyman-alpha sources. We also show that massive galaxies cause dusty starburst and become bright at infrared wavelengths.

scholarly journals Dissecting star formation in the “Atoms-for-Peace” galaxy

2018 ◽  
Vol 614 ◽  
pp. A130 ◽  
Author(s):  
K. George ◽  
P Joseph ◽  
P. Côté ◽  
S. K. Ghosh ◽  
J. B. Hutchings ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Initial Conditions ◽  
Dwarf Galaxy ◽  
Main Body ◽  
Star Forming ◽  
Uv Imaging ◽  
Star Forming Regions ◽  
The Galaxy ◽  
Tidal Tails

Context. The tidal tails of post-merger galaxies exhibit ongoing star formation far from their disks. The study of such systems can be useful for our understanding of gas condensation in diverse environments. Aims. The ongoing star formation in the tidal tails of post-merger galaxies can be directly studied from ultraviolet (UV) imaging observations. Methods. The post merger galaxy NGC7252 (“Atoms-for-Peace” galaxy) is observed with the Astrosat UV imaging telescope (UVIT) in broadband NUV and FUV filters to isolate the star-forming regions in the tidal tails and study the spatial variation in star formation rates. Results. Based on ultraviolet imaging observations, we discuss star-forming regions of ages <200 Myr in the tidal tails. We measure star formation rates in these regions and in the main body of the galaxy. The integrated star formation rate (SFR) of NGC7252 (i.e., that in the galaxy and tidal tails combined) without correcting for extinction is found to be 0.81 ± 0.01 M⊙ yr−1. We show that the integrated SFR can change by an order of magnitude if the extinction correction used in SFR derived from other proxies are taken into consideration. The star formation rates in the associated tidal dwarf galaxies (NGC7252E, SFR = 0.02 M⊙ yr−1 and NGC7252NW, SFR = 0.03 M⊙ yr−1) are typical of dwarf galaxies in the local Universe. The spatial resolution of the UV images reveals a gradient in star formation within the tidal dwarf galaxy. The star formation rates show a dependence on the distance from the centre of the galaxy. This can be due to the different initial conditions responsible for the triggering of star formation in the gas reservoir that was expelled during the recent merger in NGC7252.

scholarly journals A New Comprehensive Catalogue of Infrared Dark Clouds

2009 ◽  
Vol 5 (H15) ◽  
pp. 796-796
Author(s):  
G. A. Fuller ◽  
N. Peretto
Keyword(s):  
Star Formation ◽  
Initial Conditions ◽  
Future Studies ◽  
Dark Clouds ◽  
Star Formation Activity ◽  
Extraction Algorithm ◽  
The Galaxy ◽  
The Individual ◽  
Density Image ◽  
Infrared Dark Clouds

AbstractTo better characterise infrared dark clouds (IRDCs), and the star formation within them, a comprehensive catalogue of IRDCs has been constructed from the Spitzer GLIMPSE and MIPSGAL archival data. Mosaicing the individual survey blocks together, we have used a new extraction method to identify dark clouds up to 30′ in size, and produce a column density image of each cloud. In total the catalogue contains over 11,000 clouds, defined as connected regions with 8 micron optical depth > 0.35 (corresponding to column densities < 1022 cm−2). The extraction algorithm also identifies sub-structures (fragments) within each cloud. These Spitzer dark clouds (SDCs) range in mass from 10M⊙ to 104M⊙. About 80% of the SDCs were previously unidentified. Only ~ 30% of the SDCs are associated with 24μm point-like sources, leaving the majority of these clouds with no apparent sign of star formation activity. This new catalogue provides an important new resource for future studies of the initial conditions of star formation in the Galaxy.

scholarly journals Correlation of gas dynamics and dust in the evolved filament G82.65-02.00

2017 ◽  
Vol 608 ◽  
pp. A21 ◽  
Author(s):  
M. Saajasto ◽  
M. Juvela ◽  
K. Dobashi ◽  
T. Shimoikura ◽  
I. Ristorcelli ◽  
...  
Keyword(s):  
Column Density ◽  
Velocity Structure ◽  
Accretion Rate ◽  
Initial Conditions ◽  
Dust Emission ◽  
Line Emission ◽  
Star Forming ◽  
Virial Mass ◽  
The Masses ◽  
Main Filament

Context. The combination of line and continuum observations can provide vital insight into the formation and fragmentation of filaments and the initial conditions for star formation. We have carried out line observations to map the kinematics of an evolved, actively star forming filament G82.65-2.00. The filament was first identified from the Planck data as a region of particularly cold dust emission and was mapped at 100–500 μm as a part of the Herschel key program Galactic Cold Cores. The Herschel observations cover the central part of the filament, corresponding to a filament length of ~ 12 pc at the assumed distance of 620 pc. Aims. CO observations show that the filament has an intriguing velocity field with several velocity components around the filament. In this paper, we study the velocity structure in detail, to quantify possible mass accretion rate onto the filament, and study the masses of the cold cores located in the filament. Methods. We have carried out line observations of several molecules, including CO isotopologues, HCO+, HCN, and CS with the Osaka 1.85 m telescope and the Nobeyama 45 m telescope. The spectral line data are used to derive velocity and column density information. Results. The observations reveal several velocity components in the field, with strongest line emission concentrated to velocity range ~[3,5] km s-1. The column density of molecular hydrogen along the filament varies from 1.0 to 2.3 × 1022cm2. We have examined six cold clumps from the central part of the filament. The clumps have masses in the range 10−20M⊙ (~ 70 M⊙ in total) and are close to or above the virial mass. Furthermore, the main filament is heavily fragmented and most of the substructures have a mass lower than or close to the virial mass, suggesting that the filament is dispersing as a whole. Position-velocity maps of 12CO and 13CO lines indicate that at least one of the striations is kinematically connected to two of the clumps, potentially indicating mass accretion from the striation onto the main filament. We tentatively estimate the accretion rate to be Ṁ = 2.23 × 10-6M⊙/ yr. Conclusions. Our line observations have revealed two or possibly three velocity components connected to the filament G82.65-2.00 and putative signs of mass accretion onto the filament. The line observations combined with Herschel and WISE maps suggest a possible collision between two cloud components.

Sign in / Sign up

Export Citation Format

Share Document