The Mean Photon Path Length in Extremely Opaque Media

Adams, Thomas F.

doi:10.1086/153891

Cited by 58 publications

(54 citation statements)

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“…3) is significantly different from isotropic, but is dominated by photons of µ = 1. This result is consistent with the "single shot picture" (Adams 1975;Bonilha et al 1979), in which photons with frequency |x| < 2 mainly undergo a diffusion in the frequency space; once a photon diffuses to |x| ≥ 2, it will take "single longest excursion" to leave for outside of the halo. Therefore, the two peaks of the flux f at frequency x ± ≃ ±(2 − 3) are dominated by photons from "single longest excursion" photons, of which µ ∼ 1.…”

Section: Frequency Dependencesupporting

confidence: 86%

Angular Distribution of Ly(alpha) Resonant Photons Emergent from Optically Thick Medium

Yang¹,

Roy²,

Shu³

et al. 2012

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We investigate the angular distribution of Lyα photons transferring in or emergent from an optically thick medium. Since the evolutions of specific intensity I in the frequency space and the angular space are coupled from each other, we first develop the WENO numerical solver in order to find the time-dependent solutions of the integrodifferential equation of I in the space of frequency and angular simultaneously. We show first that the solutions with the Eddington approximation, which assume I to be linearly dependent on the angular variable µ, yield similar frequency profiles of the photon flux as that without the Eddington approximation. However, the solutions of the µ distribution evolution are significantly different from that given by Eddington approximation. First, the angular distribution of I are found to be substantially dependent on the frequency of photons. For photons with the resonant frequency ν 0 , I contains only a linear term of µ. For photons with frequency at the double peaks of the flux, the µ-distribution is highly anisotropic, in which most photons are in the direction of radial forward. Moreover, either at ν 0 or at the double peaks, the µ distributions actually are independent of the initial µ distribution of photons of the source. This is because the photons with frequency either of ν 0 or of the double peaks have undergone the process of forgetting their initial conditions due to the resonant scattering. We also show that the optically thick medium is a collimator of photons at the double peaks. Photons from the double peaks form a forward beam with very small spread angle. TR-2012-049. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution unlimited 13. SUPPLEMENTARY NOTES ABSTRACTWe investigate the angular distribution of Lyα photons transferring in or emergent from an optically thick medium. Since the evolutions of specific intensity I in the fre-quency space and the angular space are coupled from each other, we first develop the WENO numerical solver in order to find the time-dependent solutions of the integro-differential equation of I in the space of frequency and angular simultaneously. We show first that the solutions with the Eddington approximation, which assume I to be linearly dependent on the angular variable μ, yield similar frequency profiles of the photon flux as that without the Eddington approximation. However, the solutions of the μ distribution evolution are significantly different from that given by Eddington approximation. First, the angular distribution of I are found to be substantially de-pendent on the frequency of photons. For photons with the resonant frequency ν0, I contains only a linear term of μ. For photons with frequency at the double peaks of the flux, the μ-distribution is highly anisotropic, in which most photons are in the direc-tion of radial forward. Moreover, either ...

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Section: Frequency Dependencesupporting

confidence: 86%

Angular Distribution of Ly(alpha) Resonant Photons Emergent from Optically Thick Medium

Yang¹,

Roy²,

Shu³

et al. 2012

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“…The escape fraction of LyC photons from a galaxy can vary significantly on timescales of ∼10 Myr (Kimm & Cen 2014;Ma et al 2015) (Adams 1975). In reality, this estimate provides a strict upper limit to the delay time: velocity gradients and density inhomogeneities reduce t trap (Bonilha et al 1979;Dijkstra & Loeb 2008).…”

Section: Impact Of Delayed Lyα Escape Due To Trappingmentioning

confidence: 98%

THE Lyα–LyC CONNECTION: EVIDENCE FOR AN ENHANCED CONTRIBUTION OF UV-FAINT GALAXIES TO COSMIC REIONIZATION

Dijkstra

Grönke

Venkatesan

2016

ApJ

158

172

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The escape of ionizing Lyman continuum (LyC) photons requires the existence of low-N H I sightlines, which also promote escape of Lyα. We use a suite of 2500 Lyα Monte-Carlo radiative transfer simulations through models of dusty, clumpy interstellar ("multiphase") media from Gronke & Dijkstra, and compare the escape fractions of Lyα ( a f esc Ly ) and LyC radiation ( f esc ion ). We find that f esc ion and a f esc Ly are correlated: galaxies with a low a f esc Ly consistently have a low f esc ion , while galaxies with a high a f esc Ly exhibit a large dispersion in f esc ion . We argue that there is increasing observational evidence that Lyα escapes more easily from UV-faint galaxies. The correlation between f esc ion and a f esc Ly then implies that UV-faint galaxies contribute more to the ionizing background than implied by the faint-end slope of the UV luminosity function. In multiphase gases, the ionizing escape fraction is most strongly affected by the cloud covering factor, f cl , which implies that f esc ion is closely connected to the observed Lyα spectral line shape. Specifically, LyC-emitting galaxies typically having narrower, more symmetric line profiles. This prediction is qualitatively similar to that for "shell models."

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“…If the Lyα photons have to travel through a region of neutral hydrogen, they will resonantly scatter until they Doppler shift into the wings where the opacity is lower. Such a phenomenon will give rise to either a double-peaked profile (Adams 1975;Dijkstra, Haiman & Spaans 2006) or, depending on the geometry and kinematics of the neutral gas, an asymmetric profile in which one of the peaks is stronger. However, for this to be a viable explanation of the observed line profile in TN J1338, we require the Lyα to be embedded in a (partial) cocoon of neutral hydrogen of large optical depth.…”

Section: Spatially Resolved Structurementioning

confidence: 99%

Mapping the dynamics of a giant Ly α halo at z = 4.1 with MUSE: the energetics of a large-scale AGN-driven outflow around a massive, high-redshift galaxy

Swinbank

Vernet

Smail

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Citation for published item:winnkD eF wF nd ernetD tF hF F nd milD sn nd he freukD gF nd fonD F nd gontiniD F nd ihrdD tF nd ¤ ottgeringD rF tF eF nd rrutiD F nd enemnsD fF @PHISA 9wpping the dynmis of gint vy lph hlo t z a RFI with wi X the energetis of lrgeEsle eqxEdriven out)ow round mssiveD highEredshift glxyF9D wonthly noties of the oyl estronomil oietyFD RRW @PAF ppF IPWVEIQHVF Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTWe present Multi Unit Spectroscopic Explorer (MUSE) integral field unit spectroscopic observations of the ∼150 kpc Lyα halo around the z = 4

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The Mean Photon Path Length in Extremely Opaque Media

Cited by 58 publications

References 0 publications

Angular Distribution of Ly(alpha) Resonant Photons Emergent from Optically Thick Medium

Angular Distribution of Ly(alpha) Resonant Photons Emergent from Optically Thick Medium

THE Lyα–LyC CONNECTION: EVIDENCE FOR AN ENHANCED CONTRIBUTION OF UV-FAINT GALAXIES TO COSMIC REIONIZATION

Mapping the dynamics of a giant Ly α halo at z = 4.1 with MUSE: the energetics of a large-scale AGN-driven outflow around a massive, high-redshift galaxy

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