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.

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.

scholarly journals The Shining Future of UV Spectral Synthesis

2009 ◽  
Vol 5 (S262) ◽  
pp. 283-286 ◽  
Author(s):  
Anne Pellerin ◽  
Steven L. Finkelstein
Keyword(s):  
Rest Frame ◽  
Spectral Synthesis ◽  
High Redshift ◽  
Stellar Populations ◽  
Uv Spectra ◽  
Diagnostic Tools ◽  
High Redshift Galaxies ◽  
Profile Fitting ◽  
Spectral Libraries ◽  
Redshift Galaxies

AbstractWith the coming generation of instruments and telescopes capable of spectroscopy of high redshift galaxies, the spectral synthesis technique in the rest-frame UV and Far-UV range will become one of a few number of tools remaining to study their young stellar populations in detail. The rest-frame UV lines and continuum of high redshift galaxies, observed with visible and infrared telescopes on Earth, can be used for accurate line profile fitting such as Pvλλ1118, 1128, Ciiiλ1176, and Civλ1550. These lines are very precise diagnostic tools to estimate ages, metallicities, and masses of stellar populations.Here we discuss the potential for spectral synthesis of rest-frame UV spectra obtained at the Keck telescope. As an example, we study the 8 o'clock arc, a lensed galaxy at z=2.7322. We show that the poor spectral type coverage of the actual UV empirical spectral libraries limits the age and metallicity diagnostic. In order to improve our knowledge of high redshift galaxies using spectral synthesis, UV stellar libraries need to be extended to obtain accurate age, metallicity, and mass estimates likely to be occuring in young stellar populations observed in the early universe.

A new spectroscopic survey for damped Ly-alpha absorption lines from high-redshift galaxies

1991 ◽  
Vol 77 ◽  
pp. 1 ◽  
Author(s):  
Kenneth M. Lanzetta ◽  
Richard G. McMahon ◽  
Arthur M. Wolfe ◽  
David A. Turnshek ◽  
Cyril Hazard ◽  
...  
Keyword(s):  
High Redshift ◽  
Absorption Lines ◽  
High Redshift Galaxies ◽  
Redshift Galaxies

scholarly journals Detectability of cold streams into high-redshift galaxies by absorption lines

2012 ◽  
Vol 424 (3) ◽  
pp. 2292-2315 ◽  
Author(s):  
Tobias Goerdt ◽  
Avishai Dekel ◽  
Amiel Sternberg ◽  
Orly Gnat ◽  
Daniel Ceverino
Keyword(s):  
High Redshift ◽  
Absorption Lines ◽  
High Redshift Galaxies ◽  
Redshift Galaxies

scholarly journals Ultradeep near-infrared imaging of the HDF-South: rest-frame optical properties of high redshift galaxies

2003 ◽  
Author(s):  
Ivo Labbe ◽  
Marijn Franx ◽  
Gregory Rudnick ◽  
Alan F. M. Moorwood ◽  
Natascha Foerster Schreiber ◽  
...  
Keyword(s):  
Optical Properties ◽  
Rest Frame ◽  
Near Infrared ◽  
Infrared Imaging ◽  
High Redshift ◽  
Near Infrared Imaging ◽  
High Redshift Galaxies ◽  
Redshift Galaxies

scholarly journals The Green Peas: Searching for LyC Emitters at Low Redshift

2015 ◽  
Vol 11 (S319) ◽  
pp. 126-126
Author(s):  
Anne Jaskot ◽  
Sally Oey
Keyword(s):  
High Redshift ◽  
Optical Emission ◽  
Emission Lines ◽  
Gas Distribution ◽  
High Redshift Galaxies ◽  
Neutral Gas ◽  
Lyman Continuum ◽  
Green Pea ◽  
Green Peas ◽  
Redshift Galaxies

AbstractThe escape fraction of Lyman continuum (LyC) radiation from galaxies remains one of the primary uncertainties in studies of reionization. However, few LyC-emitting galaxies are known. The recently identified, low-redshift “Green Pea” (GP) galaxies exhibit a number of similarities with high-redshift galaxies, and their optical emission lines suggest they may be some of the elusive LyC emitters. Recent HST COS and ACS observations of four GPs suggest further evidence for LyC escape and give new insights into the origins of Lyα and low-ionization UV lines in high-redshift galaxies. The Lyα emission and low-ionization emission and absorption lines provide a coherent physical picture of the neutral gas distribution in the GPs and may identify LyC emitters at high redshift. The rare, low-redshift GPs hint at possible factors that may enable LyC and Lyα escape from high-redshift galaxies.

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