scholarly journals Outside the Lyman-break box: detecting Lyman continuum emitters at 3.5 < z < 5.1 with CLAUDS

2020 ◽  
Vol 494 (4) ◽  
pp. 4986-5007 ◽  
Author(s):  
U Meštrić ◽  
E V Ryan-Weber ◽  
J Cooke ◽  
R Bassett ◽  
M Sawicki ◽  
...  
Keyword(s):  
Intergalactic Medium ◽  
Hubble Space Telescope ◽  
High Redshift ◽  
Large Area ◽  
Redshift Range ◽  
Space Telescope ◽  
High Redshift Galaxies ◽  
Lyman Continuum ◽  
Deep Survey ◽  
Individual Galaxies

ABSTRACT Identifying non-contaminated sample of high-redshift galaxies with escaping Lyman continuum (LyC) flux is important for understanding the sources and evolution of cosmic reionization. We present CLAUDS (CFHT Large Area u-band deep survey) u-band photometry of the COSMOS field to probe LyC radiation from spectroscopically confirmed galaxies at $z$ ≥ 3.5 and outside the standard Lyman-break galaxy colour-selection expectations. Complementary to the CLAUDS data, we use Subaru multifilter photometry, Hubble Space Telescope (HST) multifilter imaging, and the spectroscopic surveys D10K, VUDS, and 3D-HST. We present a sample of Lyman continuum galaxy (LCG) candidates in the redshift range 3.5 ≲ $z$ ≲ 5.1. Here, we introduce 5 LCG candidates, where two are flagged quality 1 and three quality 2. The estimated $f_{\rm esc}^{\rm abs}$ for quality 1 candidates are in the range $\sim 5 - 73{{\ \rm per\ cent}}$ and $\sim 30 - 93{{\ \rm per\ cent}}$. These estimates are based on our derived parameters from individual galaxies as inputs to a range of BPASS models as well as mean intergalactic medium (IGM) and maximal intergalactic and circumgalactic media (IGM+CGM) transmission. We conclude that our search for LCGs is most likely biased to lines of sight with low H i densities or free from Lyman limit systems. Our two best LCG candidates have EW (Lyα) ≤ 50 Å and we find no correlation or anticorrelation between EW (Lyα), $f_{\rm esc}^{\rm abs}$, and Robs, the ratio of ionizing to non-ionizing observed flux in the measured passbands. Stacking candidates without solid LyC detections (S/N &lt; 3) results in an estimated $f_{\rm esc}^{\rm abs}$ from galaxies not greater than $1{{\ \rm per\ cent}}$.

scholarly journals High-redshift Lyman-α galaxies

2006 ◽  
Vol 2 (14) ◽  
pp. 254-254
Author(s):  
Sangeeta Malhotra ◽  
James E. Rhoads
Keyword(s):  
Luminosity Function ◽  
Intergalactic Medium ◽  
High Redshift ◽  
Stellar Populations ◽  
Redshift Range ◽  
High Redshift Galaxies ◽  
Redshift Galaxies

A strong Lyman-α line enables relatively easy detection of high redshift galaxies. Lyman-α galaxies are now known from z = 3 to 6.6. No evolution is discerned in the Lyman-α line luminosity function in this redshift range. This implies that the intergalactic medium at z = 6 is at least 50% ionized over more than 50% of the volume. Recent continuum detections of these galaxies from HST, MMT and Spitzer are now allowing us to address questions about the nature of these Lyman-α emitters, their stellar populations and ages. We find that by and large the Lyman-α galaxies are young galaxies dominated by stellar populations that are less than 25 Myr old.

Surveys of High-Redshift Galaxies

2013 ◽  
Author(s):  
Abraham Loeb ◽  
Steven R. Furlanetto
Keyword(s):  
Hubble Space Telescope ◽  
High Redshift ◽  
Spatial Correlations ◽  
Space Telescope ◽  
High Redshift Galaxies ◽  
James Webb Space Telescope ◽  
Observational Techniques ◽  
Mass Functions ◽  
Lower Redshift ◽  
Redshift Galaxies

This chapter details the study of high-redshift galaxies. It first outlines the telescopes used for observing these galaxies: the Hubble Space Telescope (HST) and its follow ups, as well as the next-generation telescopes such as the James Webb Space Telescope (JWST). Next, the chapter discusses the methods for isolating candidate high-redshift galaxies from the foreground population of feeble lower-redshift galaxies. After outlining the observational techniques for identifying high-redshift galaxies, the chapter turns to the luminosity and mass functions, before enumerating strategies to constrain the statistical properties of galaxies, including “one point functions” like the luminosity or stellar mass functions as well as spatial correlations.

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 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 Constraining VLBI−optical offsets in high redshift galaxies using strong gravitational lensing

2020 ◽  
Vol 494 (2) ◽  
pp. 2312-2326 ◽  
Author(s):  
Cristiana Spingola ◽  
Anna Barnacka
Keyword(s):  
Gravitational Lensing ◽  
Angular Resolution ◽  
Hubble Space Telescope ◽  
High Redshift ◽  
Monte Carlo Sampling ◽  
High Angular Resolution ◽  
Radio Emissions ◽  
High Redshift Galaxies ◽  
Long Baseline ◽  
Redshift Galaxies

ABSTRACT We present a multiwavelength analysis of two highly magnified strong gravitationally lensed galaxies, CLASS B0712+472 and CLASS B1608+656, at redshifts 1.34 and 1.394, respectively, using new VLBI (very long baseline interferometry) and archival Hubble Space Telescope observations. We reconstruct the positions of the radio and optical emissions with their uncertainties using Monte Carlo sampling. We find that in CLASS B0712+472 the optical and radio emissions are co-spatial within 2 ± 5 mas (17 ± 42 pc at redshift of 1.34). But, in CLASS B1608+656, we reconstruct an optical–radio offset of 25 ± 16 mas (214 ± 137 pc at redshift of 1.394), among the smallest offsets measured for an AGN (active galactic nucleus) at such high redshift. The spectral features indicate that CLASS B1608+656 is a post-merger galaxy, which, in combination with the optical–VLBI offset reported here, makes CLASS B1608+656 a promising candidate for a high- z offset–AGN. Furthermore, the milliarcsecond angular resolution of the VLBI observations combined with the precise lens models allow us to spatially locate the radio emission at 0.05 mas precision (0.4 pc) in CLASS B0712+472, and 0.009 mas precision (0.08 pc) in CLASS B1608+656. The search for optical–radio offsets in high redshift galaxies will be eased by the upcoming synoptic all-sky surveys, including Extremely Large Telescope and Square Kilometre Array, which are expected to find ∼105 strongly lensed galaxies, opening an era of large strong lensing samples observed at high angular resolution.

scholarly journals GLACiAR, an Open-Source Python Tool for Simulations of Source Recovery and Completeness in Galaxy Surveys

2018 ◽  
Vol 35 ◽  
Author(s):  
D. Carrasco ◽  
M. Trenti ◽  
S. Mutch ◽  
P. A. Oesch
Keyword(s):  
Hubble Space Telescope ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Software Tool ◽  
Spectral Energy ◽  
High Redshift Galaxies ◽  
Galaxy Surveys ◽  
Modelling Assumptions ◽  
Number Counts ◽  
Cosmic History

AbstractThe luminosity function is a fundamental observable for characterising how galaxies form and evolve throughout the cosmic history. One key ingredient to derive this measurement from the number counts in a survey is the characterisation of the completeness and redshift selection functions for the observations. In this paper, we present GLACiAR, an open python tool available on GitHub to estimate the completeness and selection functions in galaxy surveys. The code is tailored for multiband imaging surveys aimed at searching for high-redshift galaxies through the Lyman-break technique, but it can be applied broadly. The code generates artificial galaxies that follow Sérsic profiles with different indexes and with customisable size, redshift, and spectral energy distribution properties, adds them to input images, and measures the recovery rate. To illustrate this new software tool, we apply it to quantify the completeness and redshift selection functions for J-dropouts sources (redshift z ~ 10 galaxies) in the Hubble Space Telescope Brightest of Reionizing Galaxies Survey. Our comparison with a previous completeness analysis on the same dataset shows overall agreement, but also highlights how different modelling assumptions for the artificial sources can impact completeness estimates.

The Hubble Space Telescope Medium Deep Survey with the Wide Field and Planetary Camera. 1: Methodology and results on the field near 3C 273

1994 ◽  
Vol 437 ◽  
pp. 67 ◽  
Author(s):  
R. E. Griffiths ◽  
K. U. Ratnatunga ◽  
L. W. Neuschaefer ◽  
S. Casertano ◽  
M. Im ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Wide Field ◽  
Space Telescope ◽  
Deep Survey
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