RESONANT SCATTERING AND Lyα RADIATION EMERGENT FROM NEUTRAL HYDROGEN HALOS

Roy, Ian; Shu, Chi‐Wang; Fang, Li‐Zhi

doi:10.1088/0004-637x/716/1/604

Cited by 16 publications

(24 citation statements)

References 44 publications

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“…In Fig. 1, the data points are given by the WENO numerical solutions of Roy et al (2010). Therefore, the MC method can match the time‐dependent WENO solutions.…”

Section: Methods and Testmentioning

confidence: 99%

“…The last two curves (2000 and 3000) already overlap. The symbol points marked by the ‘+’ and ‘×’ symbols are from the WENO numerical solution of the radiative transfer equation (Roy et al 2010) at epochs η= 500 and 2000, respectively.…”

Section: Methods and Testmentioning

confidence: 99%

“…Recently, a state‐of‐the‐art numerical method based on the weighted essentially non‐oscillatory (WENO) scheme has been introduced to solve the integro‐differential equation of the radiative transfer of resonant photons (Roy et al 2009a,b; Roy, Shu & Fang 2010). It reveals many interesting features of the transfer of Lyα photons in an optically thick medium, which cannot be seen with the time‐independent solutions of the Fokker–Planck approximation.…”

Section: Introductionmentioning

confidence: 99%

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Time-dependent behaviour of Lyman α photon transfer in a high-redshift optically thick medium

Fang

2011

Monthly Notices of the Royal Astronomical Society

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Using the Monte Carlo simulation method, we investigate the time‐dependent behaviour of Lyα photon transfer in an optically thick medium of the concordance ΛCDM universe. At high redshifts, the Lyα photon escaping from the optically thick medium has a time‐scale as long as the age of the luminous object, or even comparable to the age of the Universe. In this case, time‐independent or stationary solutions of the Lyα photon transfer with resonant scattering will overlook important features of the escaped Lyα photons in physical and frequency spaces. More importantly, the expansion of the Universe means that the time‐independent solutions of the Lyα photon transfer might not exist. We show that time‐dependent solutions are sometimes essential for understanding Lyα emission and absorption at high redshifts. For Lyα photons from sources at redshift 1 +z= 10, which are surrounded by the neutral hydrogen intergalactic medium (IGM) of the ΛCDM universe, the escape coefficient is found to be always less, or much less, than one, regardless of the age or lifetime of the sources. In such an environment, we also find that even when the Lyα photon luminosity of the sources is stable, the mean surface brightness gradually increases in the first 106 yr, and then decreases with a power law of time. However, it never approaches a stable, time‐independent state. That is, all 1 +z= 10 sources in a neutral Hubble expanding IGM with Lyα luminosity L have their maximum of mean surface brightness ∼10−21(L/1043 erg s−1) erg s−1 cm−2 arcsec−2 at the age of about 106 yr. We also address the time‐dependent effects on the red damping wing profile.

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“…In Fig. 1, the data points are given by the WENO numerical solutions of Roy et al (2010). Therefore, the MC method can match the time‐dependent WENO solutions.…”

Section: Methods and Testmentioning

confidence: 99%

Section: Methods and Testmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Time-dependent behaviour of Lyman α photon transfer in a high-redshift optically thick medium

Fang

2011

Monthly Notices of the Royal Astronomical Society

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“…With the WENO solver, many interesting features of Lyα resonant photon transfer have been revealed. It shows that the double peaked frequency profile of the Lyα photon emergent from an optically thick medium generally does not follow the time-independent solutions of the P-F equation (Fang 2009;Roy et al 2009aRoy et al , 2009bRoy et al , 2009cRoy et al , 2010. The solver has also been used to calculate time-dependent features: 1) the timescale of the formation of the W-F effect; 2) the light-curve of a flash source surrounded by optically thick halo; 3) the dependence of the Lyα photon escape coefficient on the redshifts of sources; 4) the effects of dust on the double-peak profile of the emergent Lyα photons (Roy et al 2009a(Roy et al , 2009b(Roy et al , 2009c(Roy et al , 2010Yang et al 2011;Xu et al 2011).…”

Section: Introductionmentioning

confidence: 97%

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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“…Accordingly, during their quasar phases, the AGN fill the LABs with Lyα photons; the latter are trapped because of resonant scattering and released only gradually. The observable Lyα light curve is thus a very damped response to the AGN's ionizing light curve (Roy et al 2010;Xu et al 2011). Effectively, the Lyα and X-ray light curves are decorrelated.…”

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confidence: 99%

NuSTAR Hard X-Ray Data and Gemini 3D Spectra Reveal Powerful AGN and Outflow Histories in Two Low-redshift Lyα Blobs

Kawamuro

Schirmer

Turner

et al. 2017

ApJ

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We have shown that Lyman-α blobs (LABs) may still exist even at z ∼ 0.3, about 7 billion years later than most other LABs known (Schirmer et al. 2016). Their luminous Lyα and [O iii] emitters at z ∼ 0.3 offer new insights into the ionization mechanism. This paper focuses on the two X-ray brightest LABs at z ∼ 0.3, SDSS J0113+0106 (J0113) and SDSS J1155−0147 (J1155), comparable in size and luminosity to 'B1', one of the best-studied LABs at z 2. Our NuSTAR hard X-ray (3-30 keV) observations reveal powerful active galactic nuclei (AGN) with L 2−10 keV = (0.5-3) × 10 44 erg s −1 . J0113 also faded by a factor of ∼ 5 between 2014 and 2016, emphasizing that variable AGN may cause apparent ionization deficits in LABs. Joint spectral analyses including Chandra data constrain column densities of N H = 5.123 cm −2 (J0113) and N H = 6.0. J0113 is likely buried in a torus with a narrow ionization cone, but ionizing radiation is also leaking in other directions as revealed by our Gemini/GMOS 3D spectroscopy. The latter shows a bipolar outflow over 10 kpc, with a peculiar velocity profile that is best explained by AGN flickering. X-ray analysis of J1155 reveals a weakly absorbed AGN that may ionize over a wide solid angle, consistent with our 3D spectra. Extinction corrected [O iii] log-luminosities are high, ∼ 43.6. The velocity dispersions are low, ∼ 100-150 km s −1 , even at the AGN positions. We argue that this is a combination of high extinction hiding the turbulent gas, and previous outflows that have cleared the escape paths for their successors.

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RESONANT SCATTERING AND Lyα RADIATION EMERGENT FROM NEUTRAL HYDROGEN HALOS

Cited by 16 publications

References 44 publications

Time-dependent behaviour of Lyman α photon transfer in a high-redshift optically thick medium

Time-dependent behaviour of Lyman α photon transfer in a high-redshift optically thick medium

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

NuSTAR Hard X-Ray Data and Gemini 3D Spectra Reveal Powerful AGN and Outflow Histories in Two Low-redshift Lyα Blobs

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