scholarly journals What drives the redshift evolution of strong emission line ratios?

2020 ◽  
Vol 493 (1) ◽  
pp. 580-585 ◽  
Author(s):  
Fuyan Bian ◽  
Lisa J Kewley ◽  
Brent Groves ◽  
Michael A Dopita
Keyword(s):  
Ionizing Radiation ◽  
Radiation Field ◽  
High Redshift ◽  
Sloan Digital Sky Survey ◽  
Minor Role ◽  
Stellar Rotation ◽  
Current Standard ◽  
High Redshift Galaxies ◽  
Local Reference ◽  
Redshift Galaxies

ABSTRACT We study the physical mechanisms that cause the offset between low-redshift and high-redshift galaxies on the [O iii] λ5007/H β versus [N ii] λ6584/H α ‘Baldwin, Phillips & Terlevich’ (BPT) diagram using a sample of local analogues of high-redshift galaxies. These high-redshift analogue galaxies are selected from the Sloan Digital Sky Survey. Located in the same region on the BPT diagram as the ultraviolet selected galaxies at z ∼ 2, these high-redshift analogue galaxies provide an ideal local benchmark to study the offset between the local and high-redshift galaxies on the BPT diagram. We compare the nitrogen-to-oxygen ratio (N/O), the shape of the ionizing radiation field, and ionization parameters between the high-redshift analogues and a sample of local reference galaxies. The higher ionization parameter in the high-redshift analogues is the dominant physical mechanism driving the BPT offset from low- to high-redshift, particularly at high [N ii] λ6584/H α. Furthermore, the N/O ratio enhancement also plays a minor role to cause the BPT offset. However, the shape of the ionizing radiation field is unlikely to cause the BPT offset because the high-redshift analogues have a similar hard ionizing radiation field as local reference galaxies. This hard radiation field cannot be produced by the current standard stellar synthesis models. The stellar rotation and binarity may help solve the discrepancy.

scholarly journals CO Excitation, Molecular Gas Density, and Interstellar Radiation Field in Local and High-redshift Galaxies

2021 ◽  
Vol 909 (1) ◽  
pp. 56
Author(s):  
Daizhong Liu ◽  
Emanuele Daddi ◽  
Eva Schinnerer ◽  
Toshiki Saito ◽  
Adam Leroy ◽  
...  
Keyword(s):  
Radiation Field ◽  
High Redshift ◽  
Molecular Gas ◽  
Gas Density ◽  
High Redshift Galaxies ◽  
Redshift Galaxies

scholarly journals Escape of Ionizing Radiation from High‐Redshift Galaxies

2008 ◽  
Vol 672 (2) ◽  
pp. 765-775 ◽  
Author(s):  
Nickolay Y. Gnedin ◽  
Andrey V. Kravtsov ◽  
Hsiao‐Wen Chen
Keyword(s):  
Ionizing Radiation ◽  
High Redshift ◽  
High Redshift Galaxies ◽  
Redshift Galaxies

scholarly journals Fluctuating feedback-regulated escape fraction of ionizing radiation in low-mass, high-redshift galaxies

2017 ◽  
Vol 470 (1) ◽  
pp. 224-239 ◽  
Author(s):  
Maxime Trebitsch ◽  
Jérémy Blaizot ◽  
Joakim Rosdahl ◽  
Julien Devriendt ◽  
Adrianne Slyz
Keyword(s):  
Ionizing Radiation ◽  
High Redshift ◽  
High Redshift Galaxies ◽  
Low Mass ◽  
Redshift Galaxies

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.

Sign in / Sign up

Export Citation Format

Share Document