The properties of Lyman limit absorbing clouds at Z = 3 - Physical conditions in the extended gaseous halos of high-redshift galaxies

1990 ◽  
Vol 74 ◽  
pp. 37 ◽  
Author(s):  
Charles C. Steidel
Keyword(s):  
High Redshift ◽  
High Redshift Galaxies ◽  
Physical Conditions ◽  
Redshift Galaxies

scholarly journals Physical conditions in the diffuse interstellar medium of local and high-redshift galaxies: measurements based on the excitation of H2 rotational and C i  fine-structure levels

2020 ◽  
Vol 498 (2) ◽  
pp. 1531-1549
Author(s):  
V V Klimenko ◽  
S A Balashev
Keyword(s):  
Fine Structure ◽  
Interstellar Medium ◽  
Milky Way ◽  
High Redshift ◽  
Magellanic Cloud ◽  
Number Density ◽  
High Redshift Galaxies ◽  
Physical Conditions ◽  
Wide Range ◽  
Redshift Galaxies

ABSTRACT We present the results of an analysis of the physical conditions (number density, intensity of UV field, kinetic temperature) in the cold H2-bearing interstellar medium of local and high-redshift galaxies. Our measurements are based on the fit to the observed population of H2 rotational levels and C i  fine-structure levels with the help of grids of numerical models calculated with the photon-dominated region (PDR) Meudon code. A joint analysis of low H2 rotational levels and C i  fine-structure levels breaks the degeneracy in the IUV−nH plane and provides significantly tighter constraints on the number density and intensity of the UV field. Using archive data from the VLT/UVES, KECK/HIRES, HST/STIS and FUSE telescopes, we selected 12 high-redshift damped Lyα systems (DLAs) in quasar spectra and 14 H2 absorption systems along the lines of sight towards stars in the Milky Way and the Magellanic Cloud galaxies. These systems have strong H2 components, with a column density log N(H2)/[cm−2] > 18 and associated C i  absorptions. We find that H2-bearing media in high-redshift DLAs and in local galaxies have similar values of the kinetic temperatures Tkin ∼ 100 K and number density 10−500 cm−3. However, the intensity of incident UV radiation in DLAs varies in a wide range (0.1−100 units of the Mathis field), while it is ∼0.1−3 units of the Mathis field for H2 systems in the Milky Way and Large and Small Magellanic Cloud galaxies. The large dispersion of measured UV flux in DLAs is probably a consequence of the fact that the DLA sample probes galaxies selected from the overall galaxy population at high redshift, and therefore corresponds to a wide range of physical conditions.

scholarly journals TRACING THE EVOLUTION OF HIGH-REDSHIFT GALAXIES USING STELLAR ABUNDANCES

2016 ◽  
Vol 820 (1) ◽  
pp. 71 ◽  
Author(s):  
Brian D. Crosby ◽  
Brian W. O’Shea ◽  
Timothy C. Beers ◽  
Jason Tumlinson
Keyword(s):  
High Redshift ◽  
Stellar Abundances ◽  
High Redshift Galaxies ◽  
Redshift Galaxies

scholarly journals Self-consistent proto-globular cluster formation in cosmological simulations of high-redshift galaxies

2020 ◽  
Vol 493 (3) ◽  
pp. 4315-4332 ◽  
Author(s):  
Xiangcheng Ma ◽  
Michael Y Grudić ◽  
Eliot Quataert ◽  
Philip F Hopkins ◽  
Claude-André Faucher-Giguère ◽  
...  
Keyword(s):  
High Pressure ◽  
Star Formation ◽  
High Redshift ◽  
Cluster Formation ◽  
Mass Function ◽  
Cosmological Simulations ◽  
High Redshift Galaxies ◽  
Cluster Mass ◽  
Formation Efficiency ◽  
Redshift Galaxies

ABSTRACT We report the formation of bound star clusters in a sample of high-resolution cosmological zoom-in simulations of z ≥ 5 galaxies from the Feedback In Realistic Environments project. We find that bound clusters preferentially form in high-pressure clouds with gas surface densities over $10^4\, \mathrm{ M}_{\odot }\, {\rm pc}^{-2}$, where the cloud-scale star formation efficiency is near unity and young stars born in these regions are gravitationally bound at birth. These high-pressure clouds are compressed by feedback-driven winds and/or collisions of smaller clouds/gas streams in highly gas-rich, turbulent environments. The newly formed clusters follow a power-law mass function of dN/dM ∼ M−2. The cluster formation efficiency is similar across galaxies with stellar masses of ∼107–$10^{10}\, \mathrm{ M}_{\odot }$ at z ≥ 5. The age spread of cluster stars is typically a few Myr and increases with cluster mass. The metallicity dispersion of cluster members is ∼0.08 dex in $\rm [Z/H]$ and does not depend on cluster mass significantly. Our findings support the scenario that present-day old globular clusters (GCs) were formed during relatively normal star formation in high-redshift galaxies. Simulations with a stricter/looser star formation model form a factor of a few more/fewer bound clusters per stellar mass formed, while the shape of the mass function is unchanged. Simulations with a lower local star formation efficiency form more stars in bound clusters. The simulated clusters are larger than observed GCs due to finite resolution. Our simulations are among the first cosmological simulations that form bound clusters self-consistently in a wide range of high-redshift galaxies.

scholarly journals New methods for identifying Lyman continuum leakers and reionization-epoch analogues

2020 ◽  
Vol 498 (1) ◽  
pp. 164-180 ◽  
Author(s):  
Harley Katz ◽  
Dominika Ďurovčíková ◽  
Taysun Kimm ◽  
Joki Rosdahl ◽  
Jeremy Blaizot ◽  
...  
Keyword(s):  
Emission Line ◽  
Galaxy Formation ◽  
Dwarf Galaxy ◽  
High Redshift ◽  
Indirect Methods ◽  
High Redshift Galaxies ◽  
Lyman Continuum ◽  
The Universe ◽  
Ionization Parameter ◽  
Redshift Galaxies

ABSTRACT Identifying low-redshift galaxies that emit Lyman continuum radiation (LyC leakers) is one of the primary, indirect methods of studying galaxy formation in the epoch of reionization. However, not only has it proved challenging to identify such systems, it also remains uncertain whether the low-redshift LyC leakers are truly ‘analogues’ of the sources that reionized the Universe. Here, we use high-resolution cosmological radiation hydrodynamics simulations to examine whether simulated galaxies in the epoch of reionization share similar emission line properties to observed LyC leakers at z ∼ 3 and z ∼ 0. We find that the simulated galaxies with high LyC escape fractions (fesc) often exhibit high O32 and populate the same regions of the R23–O32 plane as z ∼ 3 LyC leakers. However, we show that viewing angle, metallicity, and ionization parameter can all impact where a galaxy resides on the O32–fesc plane. Based on emission line diagnostics and how they correlate with fesc, lower metallicity LyC leakers at z ∼ 3 appear to be good analogues of reionization-era galaxies. In contrast, local [S ii]-deficient galaxies do not overlap with the simulated high-redshift LyC leakers on the S ii Baldwin–Phillips–Terlevich (BPT) diagram; however, this diagnostic may still be useful for identifying leakers. We use our simulated galaxies to develop multiple new diagnostics to identify LyC leakers using infrared and nebular emission lines. We show that our model using only [C ii]158 μm and [O iii]88 μm can identify potential leakers from non-leakers from the local Dwarf Galaxy Survey. Finally, we apply this diagnostic to known high-redshift galaxies and find that MACS 1149_JD1 at z = 9.1 is the most likely galaxy to be actively contributing to the reionization of the Universe.

Spectral Modeling of Star‐forming Regions in the Ultraviolet: Stellar Metallicity Diagnostics for High‐Redshift Galaxies

2004 ◽  
Vol 615 (1) ◽  
pp. 98-117 ◽  
Author(s):  
Samantha A. Rix ◽  
Max Pettini ◽  
Claus Leitherer ◽  
Fabio Bresolin ◽  
Rolf‐Peter Kudritzki ◽  
...  
Keyword(s):  
High Redshift ◽  
Spectral Modeling ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Star Forming Regions ◽  
Redshift Galaxies

scholarly journals Accurately predicting the escape fraction of ionizing photons using rest-frame ultraviolet absorption lines

2018 ◽  
Vol 616 ◽  
pp. A30 ◽  
Author(s):  
J. Chisholm ◽  
S. Gazagnes ◽  
D. Schaerer ◽  
A. Verhamme ◽  
J. R. Rigby ◽  
...  
Keyword(s):  
Early Universe ◽  
Rest Frame ◽  
High Redshift ◽  
Flux Ratio ◽  
Companion Paper ◽  
Absorption Lines ◽  
Indirect Methods ◽  
High Redshift Galaxies ◽  
Lyman Continuum ◽  
Redshift Galaxies

The fraction of ionizing photons that escape high-redshift galaxies sensitively determines whether galaxies reionized the early Universe. However, this escape fraction cannot be measured from high-redshift galaxies because the opacity of the intergalactic medium is large at high redshifts. Without methods to measure the escape fraction of high-redshift galaxies indirectly, it is unlikely that we will know what reionized the Universe. Here, we analyze the far-ultraviolet (UV) H I (Lyman series) and low-ionization metal absorption lines of nine low-redshift, confirmed Lyman continuum emitting galaxies. We use the H I covering fractions, column densities, and dust attenuations measured in a companion paper to predict the escape fraction of ionizing photons. We find good agreement between the predicted and observed Lyman continuum escape fractions (within 1.4σ) using both the H I and ISM absorption lines. The ionizing photons escape through holes in the H I, but we show that dust attenuation reduces the fraction of photons that escape galaxies. This means that the average high-redshift galaxy likely emits more ionizing photons than low-redshift galaxies. Two other indirect methods accurately predict the escape fractions: the Lyα escape fraction and the optical [O III]/[O II] flux ratio. We use these indirect methods to predict the escape fraction of a sample of 21 galaxies with rest-frame UV spectra but without Lyman continuum observations. Many of these galaxies have low escape fractions (fesc ≤ 1%), but 11 have escape fractions >1%. Future studies will use these methods to measure the escape fractions of high-redshift galaxies, enabling upcoming telescopes to determine whether star-forming galaxies reionized the early Universe.

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