scholarly journals Is the Bremer Deep Field reionized, at z ∼ 7?

2021 ◽  
Vol 503 (3) ◽  
pp. 4242-4249
Author(s):  
J M Rodríguez Espinosa ◽  
J M Mas-Hesse ◽  
R Calvi
Keyword(s):  
Production Efficiency ◽  
Intergalactic Medium ◽  
Evolutionary Model ◽  
Photon Production ◽  
Analytic Model ◽  
Star Forming ◽  
Lyman Continuum ◽  
The Universe

ABSTRACT We show herein that the population of star-forming galaxies in the Bremer Deep Field (BDF) has enough ionizing power to form two large ionized bubbles that could be in the process of merging into a large one with a volume of 14 000 cMpc3. The sources identified in the BDF have been completed with a set of expected low-luminosity sources at z ∼ 7. We have estimated the number of ionizing photons per second produced by the different star-forming galaxies in the BDF. This number has been compared with the number that would be required to ionize the bubbles around the two overdense regions. We have used, as reference, ionizing emissivities derived from the AMIGA (Analytic Model of Intergalactic-medium and Galaxies) cosmological evolutionary model. We find that even using the most conservative estimates, with a Lyman continuum escape fraction of 10${{\ \rm per\ cent}}$, the two regions we have defined within the BDF would be reionized. Assuming more realistic estimates of the ionizing photon production efficiency, both bubbles would be in the process of merging into a large reionized bubble, such as those that through percolation completed the reionization of the Universe by z = 6. The rather small values of the escape fraction required to reionize the BDF are compatible with the low fraction of faint Ly α emitters identified in the BDF. Finally, we confirm that the low-luminosity sources represent indeed the main contributors to the BDF ionizing photon production.

scholarly journals The mean Hα EW and Lyman-continuum photon production efficiency for faint z ≈ 4−5 galaxies

2019 ◽  
Vol 627 ◽  
pp. A164 ◽  
Author(s):  
Daniel Lam ◽  
Rychard J. Bouwens ◽  
Ivo Labbé ◽  
Joop Schaye ◽  
Kasper B. Schmidt ◽  
...  
Keyword(s):  
Production Rate ◽  
Production Efficiency ◽  
Rest Frame ◽  
Strong Dependence ◽  
Photon Production ◽  
Star Forming ◽  
Lyman Continuum ◽  
The Mean

We present the first measurements of the Lyman-continuum photon production efficiency ξion, 0 at z ∼ 4–5 for galaxies fainter than 0.2 L* (−19 mag). ξion, 0 quantifies the production rate of ionizing photons with respect to the UV luminosity density assuming a fiducial escape fraction of zero. Extending previous measurements of ξion, 0 to the faint population is important, as ultra-faint galaxies are expected to contribute the bulk of the ionizing emissivity. We probe ξion, 0 to such faint magnitudes by taking advantage of 200-h depth Spitzer/IRAC observations from the GREATS program and ≈300 3 <  z <  6 galaxies with spectroscopic redshifts from the MUSE GTO Deep + Wide programs. Stacked IRAC [3.6]−[4.5] colors are derived and used to infer the Hα rest-frame equivalent widths, which range from 403 Å to 2818 Å. The derived ξion, 0 is log10(ξion,0/Hz erg−1) = 25.36 ± 0.08 over −20.5 <  MUV <  −17.5, similar to those derived for brighter galaxy samples at the same redshift and therefore suggesting that ξion shows no strong dependence on MUV. The ξion, 0 values found in our sample imply that the Lyman-continuum escape fraction for MUV ≈ −19 star-forming galaxies cannot exceed ≈8–20% in the reionization era.

scholarly journals The Lyman-continuum photon production efficiency in the high-redshift Universe

2016 ◽  
Vol 458 (1) ◽  
pp. L6-L9 ◽  
Author(s):  
Stephen M. Wilkins ◽  
Yu Feng ◽  
Tiziana Di-Matteo ◽  
Rupert Croft ◽  
Elizabeth R. Stanway ◽  
...  
Keyword(s):  
Production Efficiency ◽  
High Redshift ◽  
Photon Production ◽  
Lyman Continuum ◽  
High Redshift Universe

scholarly journals The intergalactic medium in the cosmic web

2014 ◽  
Vol 11 (S308) ◽  
pp. 364-367
Author(s):  
Nicolas Tejos
Keyword(s):  
Intergalactic Medium ◽  
Three Dimensional ◽  
Baryonic Matter ◽  
One Dimensional ◽  
Star Forming ◽  
Galaxy Surveys ◽  
Dimensional Distribution ◽  
Formation And Evolution ◽  
The Universe ◽  
Cross Matching

AbstractThe intergalactic medium (IGM) accounts for ≳ 90% of baryons at all epochs and yet its three dimensional distribution in the cosmic web remains mostly unknown. This is so because the only feasible way to observe the bulk of the IGM is through intervening absorption line systems in the spectra of bright background sources, which limits its characterization to being one-dimensional. Still, an averaged three dimensional picture can be obtained by combining and cross-matching multiple one-dimensional IGM information with three-dimensional galaxy surveys. Here, we present our recent and current efforts to map and characterize the IGM in the cosmic web using galaxies as tracers of the underlying mass distribution. In particular, we summarize our results on: (i) IGM around star-forming and non-star-forming galaxies; (ii) IGM within and around galaxy voids; and (iii) IGM in intercluster filaments. With these datasets, we can directly test the modern paradigm of structure formation and evolution of baryonic matter in the Universe.

scholarly journals Intense C III] λλ1907,1909 emission from a strong Lyman continuum emitting galaxy

2018 ◽  
Vol 616 ◽  
pp. L14 ◽  
Author(s):  
D. Schaerer ◽  
Y. I. Izotov ◽  
K. Nakajima ◽  
G. Worseck ◽  
J. Chisholm ◽  
...  
Keyword(s):  
Equivalent Width ◽  
Production Efficiency ◽  
Rest Frame ◽  
Stellar Population ◽  
Uv Spectrum ◽  
Star Forming ◽  
Uv Emission ◽  
Lyman Continuum ◽  
Low Metallicity ◽  
Imaging Spectrograph

We have obtained the first complete ultraviolet (UV) spectrum of a strong Lyman continuum (LyC) emitter at low redshift – the compact, low-metallicity, star-forming galaxy J1154+2443 – with a Lyman continuum escape fraction of 46% discovered recently. The Space Telescope Imaging Spectrograph spectrum shows strong Lyα and C III] λ1909 emission, as well as O III] λ1666. Our observations show that strong LyC emitters can have UV emission lines with a high equivalent width (e.g. EW(C III]) = 11.7 ± 2.9 Å rest-frame), although their equivalent widths should be reduced due to the loss of ionizing photons. The intrinsic ionizing photon production efficiency of J1154+2443 is high, log(ξ0ion = 25.56 erg−1 Hz), comparable to that of other recently discovered z ~ 0.3−0.4 LyC emitters. Combining our measurements and earlier determinations from the literature, we find a trend of increasing ξ0ion with increasing C III] λ1909 equivalent width, which can be understood by a combination of decreasing stellar population age and metallicity. Simple ionization and density-bounded photoionization models can explain the main observational features including the UV spectrum of J1154+2443.

scholarly journals Optically thin spatially resolved Mg ii emission maps the escape of ionizing photons

2020 ◽  
Vol 498 (2) ◽  
pp. 2554-2574 ◽  
Author(s):  
J Chisholm ◽  
J X Prochaska ◽  
D Schaerer ◽  
S Gazagnes ◽  
A Henry
Keyword(s):  
Flux Ratio ◽  
Star Forming ◽  
Spatially Resolved ◽  
Neutral Gas ◽  
Lyman Continuum ◽  
The Galaxy ◽  
Spatially Resolved Spectroscopy ◽  
Pass Through ◽  
Dust Attenuation ◽  
The Universe

ABSTRACT Early star-forming galaxies produced copious ionizing photons. A fraction of these photons escaped gas within galaxies to reionize the entire Universe. This escape fraction is crucial for determining how the Universe became reionized, but the neutral intergalactic medium precludes direct measurement of the escape fraction at high redshifts. Indirect estimates of the escape fraction must describe how the Universe was reionized. Here, we present new Keck Cosmic Web Imager spatially resolved spectroscopy of the resonant Mg ii 2800 Å doublet from a redshift 0.36 galaxy, J1503+3644, with a previously observed escape fraction of 6 per cent. The Mg ii emission has a similar spatial extent as the stellar continuum, and each of the Mg ii doublet lines are well fitted by single Gaussians. The Mg ii is optically thin. The intrinsic flux ratio of the red and blue Mg ii emission line doublet, $R=F_{2796}/F_{2803}$, is set by atomic physics to be two, but Mg$^+$ gas along the line of sight decreases R proportional to the Mg ii optical depth. Combined with the metallicity, R estimates the neutral gas column density. The observed R ranges across the galaxy from 0.8 to 2.7, implying a factor of 2 spatial variation of the relative escape fraction. All of the ionizing photons that escape J1503+3644 pass through regions of high R. We combine the Mg ii emission and dust attenuation to accurately estimate the absolute escape fractions for 10 local Lyman Continuum emitting galaxies and suggest that Mg ii can predict escape fraction within the epoch of reionization.

scholarly journals Tidal Dwarf Galaxies

1998 ◽  
Vol 11 (1) ◽  
pp. 141-144
Author(s):  
P.-A. Duc ◽  
I.F. Mirabel ◽  
E. Brinks
Keyword(s):  
Environmental Effects ◽  
Intergalactic Medium ◽  
Dwarf Galaxies ◽  
Star Forming ◽  
Evolution Of Galaxies ◽  
New Generation

The life and evolution of galaxies are dramatically affected by environmental effects. Interactions with the intergalactic medium and collisions with companions cause major perturbations in the morphology and contents of galaxies: in particular stars and gas clouds may be gravitationally pulled out from their parent galaxies during tidal encounters, forming rings, tails and bridges. This debris of collisions lies at the origin of a new generation of small galaxies, the so-called “tidal dwarf galaxies” (hereafter TDGs). Such an exotic way of forming galaxies was put forward by Schweizer (1978) and by Mirabel et al. (1992), who clearly observed the genesis of a star-forming object, out of material tidally expelled from the interacting system NGC 4038/39 (“The Antennae”). Recent studies, based on optical and HI observations, have shown that TDGs actually form a class of “recycled” objects with some properties similar to the more classical dwarf irregulars (dIrr) and blue compact dwarf galaxies (BCDs).

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 growth of the red-sequence in clusters since ≃1

2009 ◽  
Vol 5 (H15) ◽  
pp. 88-88
Author(s):  
Roberto P. Muñoz ◽  
L. F. Barrientos ◽  
B. P. Koester ◽  
D. G. Gilbank ◽  
M. D. Gladders ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Clusters ◽  
Evolutionary Model ◽  
Large Ensemble ◽  
Cluster Galaxies ◽  
Nir Imaging ◽  
Measured Change ◽  
First Time ◽  
The Universe ◽  
Red Sequence

AbstractWe use deep nIR imaging of 15 galaxy clusters at z ≃ 1 to study the build-up of the red-sequence in rich clusters since the Universe was half its present age. We measured, for the first time, the luminous-to-faint ratio of red-sequence galaxies at z=1 from a large ensemble of clusters, and found an increase of 100% in the ratio of luminous-to-faint red-sequence galaxies from z=0.45 to 1.0. The measured change in this ratio as function of redshift is well-reproduced by a simple evolutionary model developed in this work, that consists in an early truncation of the star formation for bright cluster galaxies and a delayed truncation for faint cluster galaxies.

scholarly journals Stellar populations in the highest redshift galaxies

2015 ◽  
Vol 11 (A29B) ◽  
pp. 197-198
Author(s):  
Andrew J. Bunker
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Stellar Populations ◽  
Mass Function ◽  
Initial Mass Function ◽  
Star Forming ◽  
Near Ir ◽  
James Webb Space Telescope ◽  
Large Telescopes ◽  
The Universe

AbstractI discuss stellar populations in galaxies at high redshift (z > 6), in particular the blue rest-frame UV colours which have been detected in recent years through near-IR imaging with HST. These spectral slopes of β < −2 are much more blue than star-forming galaxies at lower redshift, and may suggest less dust obscuration, lower metallicity or perhaps a different initial mass function. I describe current work on the luminosity function of high redshift star- forming galaxies, the evolution of the fraction of strong Lyman-α emitters in this population, and the contribution of the ionizing photon budget from such galaxies towards the reionization of the Universe. I also describe constraints placed by Spitzer/IRAC on stellar populations in galaxies within the first billion years, and look towards future developments in spectroscopy with Extremely Large Telescopes and the James Webb Space Telescope, including the JWST/NIRSpec GTO programme on galaxy evolution at high redshift.

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