RECORD
The Little Galaxies that Could (Reionize the Universe): Predicting Faint End Slopes & Escape Fractions at z > 4
Astrophysics of Galaxies · Submitted 16 Jun 2016
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim Convolving the UV luminosity function with $f_\mathrm{esc}$($M_\mathrm{UV}$), we find an ionizing emissivity that is (1) dominated by the faintest galaxies and (2) reionizes the universe at the appropriate rate, consistent with observational constraints of the ionizing emissivity and the optical depth to the decoupling surface tau_es, without the need for additional sources of ionizing radiation.
The compiled record
The paper's own sentences, arranged. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
Open the compiled record
The abstract, sentence by sentence
The sources that reionized the universe are still unknown, but likely candidates are faint but numerous galaxies. In this paper we present results from running a high resolution, uniform volume simulation, the Vulcan, to predict the number densities of undetectable, faint galaxies and their escape fractions of ionizing radiation, $f_\mathrm{esc}$, during reionization. Our approach combines a high spatial resolution, a realistic treatment of feedback and hydro processes, a strict threshold for minimum number of resolution elements per galaxy, and a converged measurement of $f_\mathrm{esc}$. We calibrate our physical model using a novel approach to create realistic galaxies at z=0, so the simulation is predictive at high redshifts. With this approach we can (1) robustly predict the evolution of the galaxy UV luminosity function at faint magnitudes down to $M_\mathrm{UV}$~-15, two magnitudes fainter than observations, and (2) estimate $f_\mathrm{esc}$ over a large range of galaxy masses based on the detailed stellar and gas distributions in resolved galaxies. We find steep faint end slopes, implying high number densities of faint galaxies, and the dependence of $f_\mathrm{esc}$ on the UV magnitude of a galaxy, given by the power-law: log $f_\mathrm{esc} = (0.51 \pm 0.04)M_\mathrm{UV} + 7.3 \pm 0.8$, with the faint population having $f_\mathrm{esc}$~35%. Convolving the UV luminosity function with $f_\mathrm{esc}$($M_\mathrm{UV}$), we find an ionizing emissivity that is (1) dominated by the faintest galaxies and (2) reionizes the universe at the appropriate rate, consistent with observational constraints of the ionizing emissivity and the optical depth to the decoupling surface tau_es, without the need for additional sources of ionizing radiation.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | The sources that reionized the universe are still unknown, but likely candidates are faint but numerous galaxies. | background 0.87 | 0.04 | 0.03 | hedged possibility 1.00 |
| s1 | In this paper we present results from running a high resolution, uniform volume simulation, the Vulcan, to predict the number densities of undetectable, faint galaxies and their escape fractions of ionizing radiation, $f_\mathrm{esc}$, during reionization. | contribution 0.93 | 0.96 | 0.05 | asserted 0.99 |
| s2 | Our approach combines a high spatial resolution, a realistic treatment of feedback and hydro processes, a strict threshold for minimum number of resolution elements per galaxy, and a converged measurement of $f_\mathrm{esc}$. | method 1.00 | 0.91 | 0.03 | asserted 0.98 |
| s3 | We calibrate our physical model using a novel approach to create realistic galaxies at z=0, so the simulation is predictive at high redshifts. | method 0.97 | 0.94 | 0.03 | asserted 1.00 |
| s4 | With this approach we can (1) robustly predict the evolution of the galaxy UV luminosity function at faint magnitudes down to $M_\mathrm{UV}$~-15, two magnitudes fainter than observations, and (2) estimate $f_\mathrm{esc}$ over a large range of galaxy masses based on the detailed stellar and gas distributions in resolved galaxies. | contribution 0.66 | 0.95 | 0.11 | asserted 0.86 |
| s5 | We find steep faint end slopes, implying high number densities of faint galaxies, and the dependence of $f_\mathrm{esc}$ on the UV magnitude of a galaxy, given by the power-law: log $f_\mathrm{esc} = (0.51 \pm 0.04)M_\mathrm{UV} + 7.3 \pm 0.8$, with the faint population having $f_\mathrm{esc}$~35%. | result 1.00 | 0.98 | 0.47 | asserted 1.00 |
| s6 | Convolving the UV luminosity function with $f_\mathrm{esc}$($M_\mathrm{UV}$), we find an ionizing emissivity that is (1) dominated by the faintest galaxies and (2) reionizes the universe at the appropriate rate, consistent with observational constraints of the ionizing emissivity and the optical depth to the decoupling surface tau_es, without the need for additional sources of ionizing radiation. | result 0.89 | 0.96 | 0.78 | asserted 0.91 |
What was examined, and what was not
- arXiv listing abstract v2
- full text
- figures and tables
- references and citing sentences
- relations to other papers
- P abstract
- S sections
- T body sentences
- C citations
- R cross-paper relations
The paper
Original abstract
The sources that reionized the universe are still unknown, but likely candidates are faint but numerous galaxies. In this paper we present results from running a high resolution, uniform volume simulation, the Vulcan, to predict the number densities of undetectable, faint galaxies and their escape fractions of ionizing radiation, $f_\mathrm{esc}$, during reionization. Our approach combines a high spatial resolution, a realistic treatment of feedback and hydro processes, a strict threshold for minimum number of resolution elements per galaxy, and a converged measurement of $f_\mathrm{esc}$. We calibrate our physical model using a novel approach to create realistic galaxies at z=0, so the simulation is predictive at high redshifts. With this approach we can (1) robustly predict the evolution of the galaxy UV luminosity function at faint magnitudes down to $M_\mathrm{UV}$~-15, two magnitudes fainter than observations, and (2) estimate $f_\mathrm{esc}$ over a large range of galaxy masses based on the detailed stellar and gas distributions in resolved galaxies. We find steep faint end slopes, implying high number densities of faint galaxies, and the dependence of $f_\mathrm{esc}$ on the UV magnitude of a galaxy, given by the power-law: log $f_\mathrm{esc} = (0.51 \pm 0.04)M_\mathrm{UV} + 7.3 \pm 0.8$, with the faint population having $f_\mathrm{esc}$~35%. Convolving the UV luminosity function with $f_\mathrm{esc}$($M_\mathrm{UV}$), we find an ionizing emissivity that is (1) dominated by the faintest galaxies and (2) reionizes the universe at the appropriate rate, consistent with observational constraints of the ionizing emissivity and the optical depth to the decoupling surface tau_es, without the need for additional sources of ionizing radiation.
Human review
References
How the literature uses it
2 arXiv papers cite this in 2 sentences
Papers citing it
Cites it as background 2 papers
-
Some studies [ref] contend that faint galaxies ($M_UV ≥$ -17) make only a negligible contribution, while others [ref] argue that these sources play a dominant role in the reionization of the Universe.
Modelling the star-formation activity and ionizing properties of high-redshift galaxies · Implications from the default case · 0.95
-
Escaping Lyman continuum photons from these sources create growing H ii regions around them, which grow and merge with H ii regions associated with other ionizing sources [ref] .
Self-shielding of hydrogen in the IGM during the epoch of reionization · Introduction · 0.96
What it cites · 10 sentences without a confident label
Uses the method or tool of 1 paper
-
The SPH implementation includes thermal and metal diffusion [ref] and eliminates artificial gas surface tension through the use of a geometric density mean in the SPH force expression [ref] .
Faint dwarfs as a test of DM models: WDM vs. CDM · The Simulation Parameters · 0.97
Uses data or values from 2 papers
-
With this choice of box size, however, we do not sample the knee of the UVLF at $z > 5$, so to fit the UVLF we take the observed values as a prior to our UVLF parameter search [ref] , which we'll discuss more in 3.1.
The Evolution of the Galaxy Rest-Frame Ultraviolet Luminosity Function Over the First Two Billion Years · The Simulation Parameters · 0.95
-
The yellow points [ref] is the inferred CSFR from observed gamma ray bursts, which although highly uncertain can probe to higher redshifts.
The Cosmic Star Formation Rate from the Faintest Galaxies in the Unobservable Universe · Star Formation History · 0.93
Compares with 4 papers
-
This is demonstrated in Figure [ref], which shows the evolution from $z∼4-10$ of the Schechter parameters $α$, $$ and $ϕ^*$ as the colored points, compared with observations, in black [ref] .
The Evolution of the Galaxy Rest-Frame Ultraviolet Luminosity Function Over the First Two Billion Years · Measuring the High z UVLF · 0.95
-
By integrating Equation [ref] we get $τ_es = 0.07_-0.03^+0.02$, shown as the green region in Figure [ref], right panel, and in excellent agreement with [ref] , shown as the hatched region representing $τ_es = 0.066 ±0.016$.
Planck 2015 results. XIII. Cosmological parameters · Results: Consistent View of Reionization · 0.99
-
Given that the typical size of such low mass, high-z galaxies is smaller than a few kpc, this is a significant improvement compared to other recent simulations of uniform volumes [ref] .
The EAGLE project: Simulating the evolution and assembly of galaxies and their environments · Introduction · 0.91
Cites as support 2 papers
-
Our star formation prescription has been shown to be bursty, especially in dwarf galaxies [ref] , consistent with real galaxies [ref] , and consistent with our fainter galaxies have a higher $$.
Quantitative constraints on starburst cycles in galaxies with stellar masses in the range 10**8-10**10 Msol · Escape Fractions · 0.97
-
One line of reasoning for them having a higher $$ than their local, more massive counterparts is that fainter, low mass halos are characterized by bursty SFHs [ref] and shallower potential wells.
The Star Formation Histories of Local Group Dwarf Galaxies II. Searching For Signatures of Reionization · Escape Fractions · 0.96
Discussion
Know something about this paper? Leave a comment, or highlight any passage above to comment on it.