Continuum Emission by Cooling Clouds

Dijkstra, Mark

doi:10.1088/0004-637x/690/1/82

Cited by 26 publications

(33 citation statements)

References 52 publications

(78 reference statements)

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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

1,223

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

1,223

1,720

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“…JWST will probably not have the sensitivity to detect Lyα cooling radiation from galaxies with halo virial masses M vir 10 10 M (e.g., Haiman et al 2000;Dijkstra 2009 11 may detect these low-mass galaxies through the cooling radiation emitted by molecular hydrogen (for an overview see, e.g., Appleton et al 2009). The luminosity in cooling radiation from molecular hydrogen will be strongly boosted if emitted by gas inside SN shells (Ciardi & Ferrara 2001) or by gas powered by X-ray irradiation from a central black hole (Spaans & Meijerink 2008).…”

Section: Discussionmentioning

confidence: 99%

“…The ratio of the hydrogen and helium Balmer line luminosities from recombining gas has been proposed as a telltale signature that distinguishes between first-generation, metal-free (Population III) and subsequent metal-enriched (Population II) star formation or between stellar sources and black holes (e.g., Tumlinson & Shull 2000;Bromm et al 2001;Oh et al 2001;Tumlinson et al 2001;Schaerer 2002Schaerer , 2003Johnson et al 2009). In addition, the detection of Lyα, molecular, or metal line cooling radiation from high redshifts would probe the gravitational assembly of the gas in the first halos (e.g., Haiman et al 2000;Dijkstra 2009, Mizusawa et al 2005Appleton et al 2009), offering direct insights in the structure and dynamics of the first galaxies and the surrounding intergalactic medium (e.g., Santos 2004;Dijkstra et al 2006Dijkstra et al , 2007Verhamme et al 2006;Laursen et al 2011).…”

Section: Introductionmentioning

confidence: 99%

The first galaxies - assembly of disks and prospects for direct detection

Pawlik

Milosavljević

2011

Proceedings of 25th Texas Symposium on Relativistic Astrophysics — PoS(Texas 2010)

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The James Webb Space Telescope (JWST) will enable observations of galaxies at redshifts z 10 and hence allow us to test our current understanding of structure formation at very early times. Previous work has shown that the very first galaxies inside halos with virial temperatures T vir 10 4 K and masses M vir 10 8 M at z 10 are probably too faint, by at least one order of magnitude, to be detected even in deep exposures with JWST. The light collected with JWST may therefore be dominated by radiation from galaxies inside 10 times more massive halos. We use cosmological zoomed smoothed particle hydrodynamics simulations to investigate the assembly of such galaxies and assess their observability with JWST. We compare two simulations that are identical except for the inclusion of non-equilibrium H/D chemistry and radiative cooling by molecular hydrogen. In both simulations a large fraction of the halo gas settles in two nested, extended gas disks which surround a compact massive gas core. The presence of molecular hydrogen allows the disk gas to reach low temperatures and to develop marked spiral structure but does not qualitatively change its stability against fragmentation. We post-process the simulated galaxies by combining idealized models for star formation with stellar population synthesis models to estimate the luminosities in nebular recombination lines as well as in the ultraviolet continuum. We demonstrate that JWST will be able to constrain the nature of the stellar populations in galaxies such as simulated here based on the detection of the He1640 recombination line. Extrapolation of our results to halos with masses both lower and higher than those simulated shows that JWST may find up to a thousand star-bursting galaxies in future deep exposures of the z 10 universe.

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“…Second, a multi-phase interstellar medium has sometimes been invoked to preferentially absorb UV-continuum photons (Neufeld 1991;Hansen & Oh 2006;Scarlata et al 2009;Finkelstein et al 2009). Third, gravitational cooling radiation in the absence of star formation is predicted to result in W 0 > 1000 Å (Dijkstra 2009). However, such high-equivalent width objects are probably rare, as only a few sources in Figure 3 lie at W 0 > 240 Å.…”

Section: Propertiesmentioning

confidence: 99%

NEW RESULTS FROM THE MAGELLAN IMACS SPECTROSCOPIC Lyα SURVEY: NICMOS OBSERVATIONS OF Lyα EMITTERS ATz= 5.7

Henry

Martin

Dressler

et al. 2010

ApJ

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We present NICMOS J 110 (rest-frame 1200-2100 Å) observations of the three z = 5.7 Lyα emitters discovered in the blind multislit spectroscopic survey by Martin et al. These images confirm the presence of the two sources that were previously only seen in spectroscopic observations. The third source, which is undetected in our J 110 observations, has been detected in narrowband imaging of the Cosmic Origins Survey, so our nondetection implies a rest-frame equivalent width >146 Å (3σ ). The two J 110 -detected sources have more modest rest-frame equivalent widths of 30-40 Å, but all three are typical of high-redshift Lyα emitters. In addition, the J 110 -detected sources have UV luminosities that are within a factor of 2 of L * UV , and sizes that appear compact (r hl ∼ 0. 15) in our NIC2 images-consistent with a redshift of 5.7. We use these UV-continuum and Lyα measurements to estimate the i 775 -z 850 colors of these galaxies and show that at least one and possibly all three would be missed by the i-dropout Lyman break galaxy selection. These observations help demonstrate the utility of multislit narrowband spectroscopy as a technique for finding faint emission-line galaxies.

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Continuum Emission by Cooling Clouds

Cited by 26 publications

References 52 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 first galaxies - assembly of disks and prospects for direct detection

NEW RESULTS FROM THE MAGELLAN IMACS SPECTROSCOPIC Lyα SURVEY: NICMOS OBSERVATIONS OF Lyα EMITTERS ATz= 5.7

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