Directly Observing the Galaxies Likely Responsible for Reionization

By R. Livermore, S. Finkelstein, J. Lotz. 2016

271 citations recorded by the source corpus.

We report a new analysis of the Hubble Frontier Fields clusters Abell 2744 and MACS 0416 using wavelet decomposition to remove the cluster light, enabling the detection of highly magnified (>50×) galaxies a factor of 10× fainter in luminosity than previous studies. We find 167 galaxies at , and with this sample we are able to characterize the UV luminosity function to at , −14 at , and −15 at . We find a steep faint-end slope ( ), and with our improved statistics at the faint end we reduce the fractional uncertainty on α to at and 4% at . We also investigate the systematic uncertainty due to the lens modeling by using every available lens model individually and comparing the results; this systematic fractional uncertainty on α is at all redshifts. We now directly observe galaxies in the luminosity regime where some simulations predict a change in the faint-end slope of the luminosity function, yet our results provide statistically very strong evidence against any turnover in the luminosity range probed, more consistent with simulations in which stars form in lower-mass halos. Thus, we find strong support for the extension of the steep luminosity function to at , consistent with the number of faint galaxies needed to reionize the universe under standard assumptions.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/86dbd4907db814bdb0254bf0108e3b8987e14d87

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. Richard S. Ellis
2. P. Oesch
3. M. Ouchi
4. R. Bouwens
5. G. Illingworth
6. L. Hernquist
7. J. Dunlop
8. M. Trenti

In Instrumentation

1. Richard S. Ellis
2. P. Oesch
3. R. Bouwens
4. M. Ouchi
5. G. Illingworth
6. C. Conroy
7. P. V. van Dokkum
8. M. Trenti

Citations in the corpus

• Full-data Results of Hubble Frontier Fields: UV Luminosity Functions at z ∼ 6–10 and a Consistent Picture of Cosmic Reionization (2017, methodology): “(1)Atek et al. (2014), (2)Atek et al. (2015a), (3)Coe et al. (2015), (4)Laporte et al. (2014), (5)Laporte et al. (2015), (6)Laporte et al. (2016), (7)Livermore et al. (2017), (8)McLeod et al. (2016), (9)Oesch et al. (2015) (10)Zheng et al. (2014), (11)Zitrin et al. (2014)”
• The z ∼ 6 Luminosity Function Fainter than −15 mag from the Hubble Frontier Fields: The Impact of Magnification Uncertainties (2016, background): “The faint-end slope α we derive at z ∼ 6 is −1.92±0.04 and 3.5σ shallower than the Livermore et al. (2017) faintend slope α = −2.10±0.03+0.02−0.01.”
• The SPHINX Cosmological Simulations of the First Billion Years: the Impact of Binary Stars on Reionization★ (2018, methodology): “7 and compared to observations from Bouwens et al. (2017) and Livermore et al. (2017).”
• The Universe Is Reionizing at z ∼ 7: Bayesian Inference of the IGM Neutral Fraction Using Lyα Emission from Galaxies (2017, methodology): “…draw a realistic sample of LBGs at z ∼ 7 from the Mason et al. (2015) UV luminosity function model (which is consistent with all observations, including new deep data from the Hubble Frontier Fields at z∼> 7 e.g., Atek et al. 2015b; McLeod et al. 2016; Livermore et al. 2017; Bouwens et al. 2017a).”
• Rapid Reionization by the Oligarchs: The Case for Massive, UV-bright, Star-forming Galaxies with High Escape Fractions (2019, background): “Our best-fit faint-end slope values are somewhat shallower than what is reported in the recent literature from observations (Bouwens et al. 2017; Livermore et al. 2017; Atek et al. 2018).”
• Evolution of the AGN UV luminosity function from redshift 7.5 (2018, background): “High-redshift galaxies down to rest-frame UV magnitude MUV = −12.5 at z = 6 (Livermore et al. 2017) and redshifts up to z = 11.1 (Oesch et al. 2016) have now been reported.”
• Gravitational probes of dark matter physics (2017, background): “At high (z ∼ 10) redshifts, dwarf galaxies are expected to reionize the Universe; there are simply not enough big galaxies or quasars at early times to yield sufficient ionizing photons [582, 583, 584, 585, 586, 587, 588].”
• The extreme faint end of the UV luminosity function at z ∼ 6 through gravitational telescopes: a comprehensive assessment of strong lensing uncertainties (2018, background): “For instance, the galaxy luminosity function and the ability of faint galaxies to reionize the Universe was the focus of multiple studies from different groups (e.g., Atek et al. 2015b; Bouwens et al. 2017b; Livermore et al. 2017; Ishigaki et al. 2018; Yue et al. 2017).”
• A Comprehensive Study of Galaxies at z ∼ 9–16 Found in the Early JWST Data: Ultraviolet Luminosity Functions and Cosmic Star Formation History at the Pre-reionization Epoch (2022, background): “…clusters, e.g., with HFF data, via gravitational lensing magnification (Atek et al. 2015, 2018; Ishigaki et al. 2015, 2018; Laporte et al. 2016; Livermore et al. 2017; Oesch et al. 2018), while the faint-end slopes and luminosity function turnovers are poorly constrained due to the limited…”
• Constraining the mass of light bosonic dark matter using SDSS Lyman-α forest (2017, background): “Recent estimations of the high-redshift UV-luminosity function (Bouwens et al. 2015; Livermore et al. 2017), as derived from deep observations such as the Hubble Frontier Fields, MNRAS 000, 1–11 (2017) are still subject to large uncertainties (Bouwens et al. 2017) but they do not clearly point…”
• Great Optically Luminous Dropout Research Using Subaru HSC (GOLDRUSH). I. UV Luminosity Functions at $z \sim 4-7$ Derived with the Half-Million Dropouts on the 100 deg$^2$ Sky (2017, background): “…sources with the Hubble Frontier Fields (HFF) project, which takes advantage of the gravitational lens magnification effects of galaxy clusters (Ishigaki et al. 2015; Atek et al. 2015; Kawamata et al. 2016; Castellano et al. 2016; McLeod et al. 2016; Livermore et al. 2017; Ishigaki et al. 2017).”
• The Dearth of z ∼ 10 Galaxies in All HST Legacy Fields—The Rapid Evolution of the Galaxy Population in the First 500 Myr (2017, unknown): “Several authors have developed comparable techniques to deal with the ICL (e.g. Atek et al. 2015; Merlin et al. 2016; Bouwens et al. 2017b; Livermore et al. 2017).”