The cool side of Lyman alpha emitters

Dayal, Pratika; Ferrara, Andrea; Saro, A.

doi:10.1111/j.1365-2966.2009.15995.x

Cited by 61 publications

(132 citation statements)

References 71 publications

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“…We assume here that Lyα suffers the same dust extinction as LyC, a simple treatment that is unlikely to capture the complex radiative transfer physics of the Lyα line as it propagates through the dusty ISM (see, e.g., Caplan & Deharveng 1986;Neufeld 1991;Dijkstra 2009;Scarlata et al 2009;Dayal et al 2010). Inserting Equation (57) into (2) yields the additional flux observed at ν o ν α from galaxy Lyα: where 1 + z α = (ν α /ν o )(1 + z o ).…”

Section: Lyα Emission From Galaxiesmentioning

confidence: 99%

Radiative Transfer in a Clumpy Universe. Iv. New Synthesis Models of the Cosmic Uv/X-Ray Background

Haardt

Madau

2012

ApJ

1,204

1,720

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We present improved synthesis models of the evolving spectrum of the UV/X-ray diffuse background, updating and extending our previous results. Five new main components are added to our radiative transfer code CUBA: (1) the sawtooth modulation of the background intensity from resonant line absorption in the Lyman series of cosmic hydrogen and helium; (2) the X-ray emission from the obscured and unobscured quasars that gives origin to the X-ray background; (3) a piecewise parameterization of the distribution in redshift and column density of intergalactic absorbers that fits recent measurements of the mean free path of 1 ryd photons; (4) an accurate treatment of the photoionization structure of absorbers, which enters in the calculation of the helium continuum opacity and recombination emissivity; and (5) the UV emission from star-forming galaxies at all redshifts. We provide tables of the predicted H i and He ii photoionization and photoheating rates for use, e.g., in cosmological hydrodynamics simulations of the Lyα forest and a new metallicity-dependent calibration to the UV luminosity density-star formation rate density relation. A "minimal cosmic reionization model" is also presented in which the galaxy UV emissivity traces recent determinations of the cosmic history of star formation, the luminosity-weighted escape fraction of hydrogen-ionizing radiation increases rapidly with look-back time, the clumping factor of the highredshift intergalactic medium evolves following the results of hydrodynamic simulations, and Population III stars and miniquasars make a negligible contribution to the metagalactic flux. The model provides a good fit to the hydrogenionization rates inferred from flux decrement and proximity effect measurements, predicts that cosmological H ii (He iii) regions overlap at redshift 6.7 (2.8), and yields an optical depth to Thomson scattering, τ es = 0.084 that is in agreement with Wilkinson Microwave Anisotropy Probe results. Our new background intensities and spectra are sensitive to a number of poorly determined input parameters and suffer from various degeneracies. Their predictive power should be constantly tested against new observations. We are therefore making our redshift-dependent UV/X emissivities and CUBA outputs freely available for public use at http://www.ucolick.org/∼pmadau/CUBA.

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Section: Lyα Emission From Galaxiesmentioning

confidence: 99%

Radiative Transfer in a Clumpy Universe. Iv. New Synthesis Models of the Cosmic Uv/X-Ray Background

Haardt

Madau

2012

ApJ

1,204

1,720

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“…We also self-consistently compute the dust mass and attenuation for each galaxy in the simulation box assuming type II SN (SNII) to be the main dust producers (Maiolino et al 2006;Stratta et al 2007). The dust mass is converted into an optical depth to UV photons assuming the dust is made of carbonaceous grains spatially distributed as the gas (see Dayal et al 2010 andFerrera 2012 for complete details of this calculation). The predicted observed UV luminosity is then L obs c = L int c × fc, where fc is the fraction of continuum photons that escape unattenuated by dust.…”

Section: Comparison With Galaxy-formation Model Predictionsmentioning

confidence: 99%

The UV continua and inferred stellar populations of galaxies at z ≃ 7–9 revealed by the Hubble Ultra-Deep Field 2012 campaign

Dunlop¹,

Rogers²,

McLure³

et al. 2013

Monthly Notices of the Royal Astronomical Society

172

227

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We use the new ultra-deep, near-infrared imaging of the Hubble Ultra-Deep Field (HUDF) provided by our UDF12 Hubble Space Telescope (HST) WFC3/IR campaign to explore the rest-frame ultraviolet (UV) properties of galaxies at redshifts z > 6.5. We present the first unbiased measurement of the average UV power-law index, β , (f λ ∝ λ β ) for faint galaxies at z ≃ 7, the first meaningful measurements of β at z ≃ 8, and tentative estimates for a new sample of galaxies at z ≃ 9. Utilising galaxy selection in the new F140W (J 140 ) imaging to minimize colour bias, and applying both colour and power-law estimators of β, we find β = −2.1 ± 0.2 at z ≃ 7 for galaxies with M UV ≃ −18. This means that the faintest galaxies uncovered at this epoch have, on average, UV colours no more extreme than those displayed by the bluest star-forming galaxies at low redshift. At z ≃ 8 we find a similar value, β = −1.9 ± 0.3. At z ≃ 9, we find β = −1.8 ± 0.6, essentially unchanged from z ≃ 6 − 7 (albeit highly uncertain). Finally, we show that there is as yet no evidence for a significant intrinsic scatter in β within our new, robust z ≃ 7 galaxy sample. Our results are most easily explained by a population of steadily star-forming galaxies with either ≃ solar metallicity and zero dust, or moderately sub-solar (≃ 10 − 20%) metallicity with modest dust obscuration (A V ≃ 0.1 − 0.2). This latter interpretation is consistent with the predictions of a state-of-the-art galaxy-formation simulation, which also suggests that a significant population of very-low metallicity, dust-free galaxies with β ≃ −2.5 may not emerge until M UV > −16, a regime likely to remain inaccessible until the James Webb Space Telescope.

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“…This is easily understood, as we will see later on, as a result of the relatively low stellar masses and metallicities characterizing these objects. Dust can, however, become more important in luminous Lyman break galaxies (LBGs) and Lyman alpha emitters (LAEs) as many studies have shown (Lai et al 2007; Atek et al 2008; Dayal, Ferrara & Gallerani 2008; Nagamine, Zhang & Hernquist 2008; Dayal et al 2009; Finkelstein et al 2009; Dayal, Ferrara & Saro 2010; Dayal, Maselli & Ferrara 2011).…”

Section: Luminosity Functionmentioning

confidence: 99%

Simulating high-redshift galaxies

Salvaterra

Ferrara

Dayal

2011

Monthly Notices of the Royal Astronomical Society

Self Cite

153

172

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Recent observations have gathered a considerable sample of high redshift galaxy candidates and determined the evolution of their luminosity function (LF). To interpret these findings, we use cosmological SPH simulations including, in addition to standard physical processes, a detailed treatment of the Pop III-Pop II transition in early objects. The simulated high-z galaxies match remarkably well the amplitude and slope of the observed LF in the redshift range 59.4) start of their star formation activity; the specific star formation rate is almost independent of galactic stellar mass. These objects are enriched rapidly with metals and galaxies identified by HST/WFC3 (M_UV < -18) show metallicities ~0.1 Zsun even at z=7-8. Most of the simulated galaxies at z~7 (noticeably the smallest ones) are virtually dust-free, and none of them has an extinction larger than E(B-V) = 0.01. The bulk (50%) of the ionizing photons is produced by objects populating the faint-end of the LF (M_UV < -16), which JWST will resolve up to z=7.3. PopIII stars continue to form essentially at all redshifts; however, at z=6 (z=10) the contribution of Pop III stars to the total galactic luminosity is always less than 5% for M_UV < -17 (M_UV < -16). The typical high-z galaxies closely resemble the GRB host galaxy population observed at lower redshifts, strongly encouraging the use of GRBs to detect the first galaxies.Comment: 14 pages, 10 figures, MNRAS in pres

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The cool side of Lyman alpha emitters

Cited by 61 publications

References 71 publications

Radiative Transfer in a Clumpy Universe. Iv. New Synthesis Models of the Cosmic Uv/X-Ray Background

Radiative Transfer in a Clumpy Universe. Iv. New Synthesis Models of the Cosmic Uv/X-Ray Background

The UV continua and inferred stellar populations of galaxies at z ≃ 7–9 revealed by the Hubble Ultra-Deep Field 2012 campaign

Simulating high-redshift galaxies

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