scholarly journals Starbursting [O iii] emitters and quiescent [C ii] emitters in the reionization era

2020 ◽  
Vol 498 (4) ◽  
pp. 5541-5556 ◽  
Author(s):  
Shohei Arata ◽  
Hidenobu Yajima ◽  
Kentaro Nagamine ◽  
Makito Abe ◽  
Sadegh Khochfar
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Line Emission ◽  
Abundance Ratio ◽  
Relative Distribution ◽  
Metal Line ◽  
Hydrodynamic Simulations ◽  
Neutral Gas ◽  
Solar Metallicity ◽  
Supernova Feedback

ABSTRACT Recent observations have successfully detected [O iii] $88.3\, {\rm \mu m}$ and [C ii] $157.6\, {\rm \mu m}$ lines from galaxies in the early Universe with the Atacama Large Millimeter Array. Combining cosmological hydrodynamic simulations and radiative transfer calculations, we present relations between the metal line emission and galaxy evolution at z = 6–15. We find that galaxies during their starburst phases have high [O iii] luminosity of ${\sim}10^{42}~\rm erg~s^{-1}$. Once supernova feedback quenches star formation, [O iii] luminosities rapidly decrease and continue to be zero for ${\sim}100\, {\rm Myr}$. The slope of the relation between $\log {(\rm SFR/\rm M_{\odot }~ yr^{-1})}$ and $\log {(L_{\rm [O\, \small {III}]}/\mathrm{L}_{\odot })}$ at z = 6–9 is 1.03, and 1.43 for $\log {(L_{\rm [C\, \small {II}]}/\mathrm{L}_{\odot })}$. As gas metallicity increases from sub-solar to solar metallicity by metal enrichment from star formation and feedback, the line luminosity ratio $L_{\rm [O\, \small {III}]} / L_{\rm [C\, \small {II}]}$ decreases from ∼10 to ∼1 because the O/C abundance ratio decreases due to carbon-rich winds from AGB stars and the mass ratio of H ii to H i regions decreases due to rapid recombination. Therefore, we suggest that the combination of [O iii] and [C ii] lines is a good probe to investigate the relative distribution of ionized and neutral gas in high-z galaxies. In addition, we show that deep [C ii] observations with a sensitivity of ∼10−2 mJy arcsec−2 can probe the extended neutral gas discs of high-z galaxies.

scholarly journals H i imaging of dwarf star-forming galaxies: masses, morphologies, and gas deficiencies

2020 ◽  
Vol 498 (4) ◽  
pp. 4745-4789
Author(s):  
S Jaiswal ◽  
A Omar
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Surface Density ◽  
Column Density ◽  
Line Emission ◽  
Scaling Relations ◽  
Dwarf Star ◽  
Star Forming ◽  
Average Value ◽  
Tidal Interactions

ABSTRACT The Giant Meter-wave Radio Telescope observations of the H i 21 cm-line emission from 13 nearby dwarf star-forming galaxies are presented. These galaxies are selected from the catalogues of Wolf−Rayet galaxies having very young (≤10 Myr) star formation. The ranges of star formation rates and stellar masses of the sample galaxies are 0.03–1.7 M⊙ yr−1 and 0.04–22.3 × 108 M⊙, respectively. The H i line emission is detected from 12 galaxies with peak column density >1 × 1021 cm−2. The 3σ H i column density sensitivities per channel width of 7 km s−1 for low (60 arcsec × 60 arcsec) resolution images are in the range 0.8–1.9 × 1019 cm−2. The H i channel images, moment images, global profiles, and mass surface density profiles are presented here. The average value of the peak H i mass surface density is estimated to be ∼2.5 M⊙ pc−2, which is significantly less compared to that in massive spiral galaxies. The scaling relations of $(M_{stars} + M_{\rm H\, I} + M_{\rm He})$versus Mdyn, gas fraction versus MB, $M_{\rm H\, I}$versus Mstars, H i-to-stellar mass ratio versus Mstars, and $M_{\rm H\, I}$versus $D_{\rm H\, I}$for the sample galaxies are estimated. These scaling relations can be used to constraint the key parameters in the galaxy evolution models. These galaxies are residing in group environment with galaxy density up to eight galaxy Mpc−3. An H i mass deficiency (with DEFH i > 0.3) is noticed in majority of galaxies for their optical diameters as compared to galaxies in field environments. Clear signatures of tidal interactions in these galaxies could be inferred using the H i images. Isolated H i clouds without known optical counterparts are seen in the vicinity of several galaxies. H i emission envelope is found to be having an offset from the optical envelope in several galaxies. Consistent with the previous studies on galaxy evolution in group environments, tidal interactions seem to play an important role in triggering recent star formation.

scholarly journals The growth of H ii regions around massive stars: the role of metallicity and dust

2020 ◽  
Author(s):  
Ahmad A Ali
Keyword(s):  
Star Formation ◽  
Radiation Pressure ◽  
Massive Stars ◽  
Particle Method ◽  
Diffuse Radiation ◽  
Uv Absorption ◽  
Expansion Velocity ◽  
H Ii Regions ◽  
Metal Line ◽  
Neutral Gas

Abstract Gas metallicity Z and the related dust-to-gas ratio fd can influence the growth of H ii regions via metal line cooling and UV absorption. We model these effects in star-forming regions containing massive stars. We compute stellar feedback from photoionization and radiation pressure (RP) using Monte Carlo radiative transfer coupled with hydrodynamics, including stellar and diffuse radiation fields. We follow a 105 M⊙ turbulent cloud with Z/Z⊙ = 2, 1, 0.5, 0.1 and fd = 0.01Z/Z⊙ with a cluster-sink particle method for star formation. The models evolve for at least 1.5Myr under feedback. Lower Z results in higher temperatures and therefore larger H ii regions. For Z ≥ Z⊙, radiation pressure Prad can dominate locally over the gas pressure Pgas in the inner half-parsec around sink particles. Globally, the ratio of Prad/Pgas is around 1 (2Z⊙), 0.3 (Z⊙), 0.1 (0.5Z⊙), and 0.03 (0.1Z⊙). In the solar model, excluding RP results in an ionized volume several times smaller than the fiducial model with both mechanisms. Excluding RP and UV attenuation by dust results in a larger ionized volume than the fiducial case. That is, UV absorption hinders growth more than RP helps it. The radial expansion velocity of ionized gas reaches +15km s−1 outwards, while neutral gas has inward velocities for most of the runtime, except for 0.1Z⊙ which exceeds +4km s−1. Z and fd do not significantly alter the star formation efficiency, rate, or cluster half-mass radius, with the exception of 0.1Z⊙ due to the earlier expulsion of neutral gas.

scholarly journals The Interstellar Medium in Star Burst Galaxies

1987 ◽  
Vol 115 ◽  
pp. 614-614
Author(s):  
R. Genzel ◽  
J. B. Lugten ◽  
M. K. Crawford ◽  
D. M. Watson
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Line Emission ◽  
Far Infrared ◽  
High Rate ◽  
Interstellar Gas ◽  
Infrared Observations ◽  
Bolometric Luminosity ◽  
Neutral Gas ◽  
Molecular Lines

We report far-infrared observations of [0 I], [C II] and [O III] fine structure emission lines toward the nuclei of M82 and 7 other galaxies with a high rate of star formation. The far-infrared line emission is bright, contains about 0.5% of the bolometric luminosity in the central 60″, and is spatially concentrated toward the nuclei. In these galaxies between 10 and 30% of the interstellar gas near the nuclei is contained in a warm, atomic component. This atomic gas is probably located at the UV photodissociated surfaces of molecular clouds. The neutral gas in M82 has a temperature of ∼ 200 K, hydrogen density of ∼ 3 × 104 cm−3 and is very clumpy, indicating that the interstellar medium in this star burst galaxy is very different from that in the disk of our own galaxy. We discuss the implications of the infrared observations for the interpretation of mm molecular lines and for star formation at the nuclei of star burst galaxies.

scholarly journals Local HI: Constraints on the Evolution of the HI Content of the Universe

1997 ◽  
Vol 14 (1) ◽  
pp. 31-36 ◽  
Author(s):  
F. H. Briggs
Keyword(s):  
Star Formation ◽  
Absorption Line ◽  
Galaxy Evolution ◽  
Column Density ◽  
Absorption Lines ◽  
Reliable Measure ◽  
Redshift Range ◽  
Neutral Gas ◽  
Present Rate ◽  
The Universe

AbstractAnalyses of QSO absorption lines show that the HI content has evolved over the redshift range z = 5 to z = 0. The 21-cm line measurements of the z = 0 HI content avoid several biases inherent in the absorption-line technique, such as the influence of evolving dust content in the absorbers, and will produce a reliable measure to anchor theories of galaxy evolution. Examples of important questions to be addressed by local HI surveys are: (1) Is there a significant population of gas-rich galaxies or intergalactic clouds that is missing from the census of optically selected galaxies? (2) Is there an adequate reservoir of neutral gas to substantially prolong star formation at its present rate? (3) Are there massive objects of such low HI column density that they can have escaped detection in the ‘unbiased’ HI surveys that have been conducted so far?

scholarly journals The energetics of turbulent molecular gas and star formation

2011 ◽  
Vol 7 (S284) ◽  
pp. 330-336
Author(s):  
François Boulanger
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Mechanical Energy ◽  
Line Emission ◽  
Turbulent Energy ◽  
Molecular Gas ◽  
Interstellar Matter ◽  
Mass Ratio ◽  
Interstellar Turbulence ◽  
Mechanical Energy Dissipation

AbstractThe role interstellar turbulence plays in regulating star formation is a much debated research topic. In this paper, I take an observational view point in presenting observations of H2 line emission from extragalactic sources. I highlight key results from these observations. (1) H2 line emission is a main cooling channel of molecular gas. It is a tracer of mechanical energy dissipation complementing mass tracers in describing the dynamical state of molecular gas in galaxies. (2) Spectroscopy of warm H2 observations with the Spitzer Space Telescope and the SINFONI spectro-imager at ESO provide evidence of shock excited H2 line emission in galaxies that exemplify the main agents of galaxy evolution. (3) The dissipation of mechanical energy involves a turbulent energy cascade and the cycling of interstellar matter across ISM phases, including the formation of H2 gas from warm atomic gas. (4) In Stephan's Quintet and the radio galaxy 3C326, two sources with a high H2 luminosity to mass ratio (i.e. a high dissipation rate per unit mass), turbulence is observed to quench star formation. In the Antennae merger, star formation is observed to proceed where the turbulent kinetic energy is being dissipated.

scholarly journals Hydrodynamic simulations of an isolated star-forming gas cloud in the Virgo cluster

2020 ◽  
Vol 499 (4) ◽  
pp. 5873-5890
Author(s):  
Francesco Calura ◽  
Michele Bellazzini ◽  
Annibale D’Ercole
Keyword(s):  
Star Formation ◽  
Three Dimensional ◽  
Virgo Cluster ◽  
General Interest ◽  
Hydrodynamic Simulations ◽  
Star Forming ◽  
Neutral Gas ◽  
Asymmetric Shape ◽  
Gas Cloud ◽  
Cold Gas

ABSTRACT We present a suite of three-dimensional, high-resolution hydrodynamic simulations that follow the evolution of a massive (107 M⊙) pressure-confined, star-forming neutral gas cloud moving through a hot intracluster medium (ICM). The main goal of the analysis is to get theoretical insight into the lifetimes and evolution of stellar systems like the recently discovered star-forming cloud SECCO 1 in the Virgo cluster of galaxies, but it may be of general interest for the study of the star-forming gas clumps that are observed in the tails of ram pressure stripped galaxies. Building up on a previous, simple simulation, we explored the effect of different relative velocity of the cloud and larger temperature of the ICM, as well as the effect of the cloud self-gravity. Moreover, we performed a simulation including star formation and stellar feedback, allowing for a first time a direct comparison with the observed properties of the stars in the system. The survivability of the cold gas in the simulated clouds is granted on time-scales of the order of 1 Gyr, with final cold gas fractions generally >0.75. In all cases, the simulated systems end up, after 1 Gyr of evolution, as symmetric clouds in pressure equilibrium with the external hot gas. We also confirm that gravity played a negligible role at the largest scales on the evolution of the clouds. In our simulation with star formation, star formation begins immediately, it peaks at the earliest times, and decreases monotonically with time. Inhomogeneous supernova explosions are the cause of an asymmetric shape of the gas cloud, facilitating the development of instabilities and the decrease of the cold gas fraction.

scholarly journals A Review of Recent Observations of Galactic Winds Driven by Star Formation

Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 138 ◽  
Author(s):  
David Rupke
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Near Infrared ◽  
Current Model ◽  
Imaging Spectroscopy ◽  
Star Forming ◽  
Neutral Gas ◽  
Direct Observations ◽  
Galactic Winds ◽  
Large Numbers

Galaxy-scale outflows of gas, or galactic winds (GWs), driven by energy from star formation are a pivotal mechanism for regulation of star formation in the current model of galaxy evolution. Observations of this phenomenon have proliferated through the wide application of old techniques on large samples of galaxies, the development of new methods, and advances in telescopes and instrumentation. I review the diverse portfolio of direct observations of stellar GWs since 2010. Maturing measurements of the ionized and neutral gas properties of nearby winds have been joined by exciting new probes of molecular gas and dust. Low-z techniques have been newly applied in large numbers at high z. The explosion of optical and near-infrared 3D imaging spectroscopy has revealed the complex, multiphase structure of nearby GWs. These observations point to stellar GWs being a common feature of rapidly star-forming galaxies throughout at least the second half of cosmic history, and suggest that scaling relationships between outflow and galaxy properties persist over this period. The simple model of a modest-velocity, biconical flow of multiphase gas and dust perpendicular to galaxy disks continues to be a robust descriptor of these flows.

scholarly journals Galaxy evolution and radiative properties in the early universe: Multi-wavelength analysis in cosmological simulations

2019 ◽  
Vol 15 (S352) ◽  
pp. 55-59
Author(s):  
Shohei Arata ◽  
Hidenobu Yajima ◽  
Kentaro Nagamine ◽  
Yuexing Li ◽  
Sadegh Khochfar
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Radiative Properties ◽  
Star Formation History ◽  
Star Forming ◽  
Bolometric Luminosity ◽  
Star Forming Regions ◽  
Neutral Gas ◽  
Multi Wavelength ◽  
First Galaxies

AbstractRecent observations have successfully detected UV or infrared flux from galaxies at the epoch of reionization. However, the origin of their radiative properties has not been fully understood yet. Combining cosmological hydrodynamic simulations and radiative transfer calculations, we present theoretical predictions of multi-wavelength radiative properties of the first galaxies at z = 6–15. We find that most of the gas and dust are ejected from star-forming regions due to supernova (SN) feedback, which allows UV photons to escape. We show that the peak of SED rapidly shifts between UV and infrared wavelengths on a timescale of 100 Myr due to intermittent star formation and feedback. When dusty gas covers the star-forming regions, the galaxies become bright in the observed-frame sub-millimeter wavelengths. In addition, we find that the escape fraction of ionizing photons also changes between 1–40% at z > 10. The mass fraction of H ii region changes with star formation history, resulting in fluctuations of metal lines and Lyman-α line luminosities. In the starbursting phase of galaxies with a halo mass ∼1011Mȯ (1012Mȯ), the simulated galaxy has L[OIII] ∼ 1042 (1043) erg s−1, which is consistent with the observed star-forming galaxies at z > 7. Our simulations suggest that deep [Cii] observation with ALMA can trace the distribution of neutral gas extending over ∼20 physical kpc. We also find that the luminosity ratio L[OIII]/L[CII] decreases with bolometric luminosity due to metal enrichment. Our simulations show that the combination of multi-wavelength observations by ALMA and JWST will be able to reveal the multi-phase ISM structure and the transition from starbursting to outflowing phases of high-z galaxies.

Magneto-Hydrodynamic simulations on galaxy modeling

2019 ◽  
Vol 15 (S341) ◽  
pp. 320-322
Author(s):  
Wei-Chen Wang ◽  
Ke-Jung Chen
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
High Resolution ◽  
Galaxy Evolution ◽  
Previous Literature ◽  
Hydrodynamic Simulation ◽  
Hydrodynamic Simulations ◽  
Recent Advancement ◽  
The Magnetic Field

AbstractMagnetic field plays an important role in star formation and galaxy evolution. Previous studies discussed about the origin of magnetic field and its effect to the environment. With the recent advancement of supercomputers, adding the magnetic field to a cosmological hydrodynamic simulations only become feasible. In this proceeding, we present the results of high-resolution magneto-hydrodynamic simulation with GIZMO and compare our simulation result with the previous literature and the observations.

scholarly journals Degeneracies between modified gravity and baryonic physics

2018 ◽  
Vol 615 ◽  
pp. A134 ◽  
Author(s):  
Thor A. S. Ellewsen ◽  
Bridget Falck ◽  
David F. Mota
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Modified Gravity ◽  
Cold Dark Matter ◽  
Density Profiles ◽  
Hydrodynamic Simulations ◽  
Cold Dark Matter Model ◽  
Modified Gravity Theories ◽  
Hydrodynamic Processes ◽  
Supernova Feedback

In order to determine the observable signatures of modified gravity theories, it is important to consider the effect of baryonic physics. We used a modified version of the ISIS code to run cosmological hydrodynamic simulations in order to study degeneracies between modified gravity and radiative hydrodynamic processes. One of the simulations was the standard Λ cold dark matter model and four were variations of the Symmetron model. For each model we ran three variations of baryonic processes: nonradiative hydrodynamics; cooling and star formation; and cooling, star formation, and supernova feedback. We constructed stacked gas density, temperature, and dark matter density profiles of the halos in the simulations, and studied the differences between them. We find that both radiative variations of the models show degeneracies between their processes and at least two of the three parameters defining the Symmetron model.

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