RADIATIVE TRANSFER IN A CLUMPY UNIVERSE WITH CUBA
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Transcript of RADIATIVE TRANSFER IN A CLUMPY UNIVERSE WITH CUBA
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PIERO MADAUUC SANTA CRUZ
RADIATIVE TRANSFER IN A CLUMPY UNIVERSE WITH CUBA
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UV radiation from stars and accreting MBHs keeps the universe ionized, shapes the IGM, and regulates gas cooling and star formation in galaxies.
The integrated UVB traces the rise and fall of the quasar population, the cosmic history of star formation in galaxies, the evolving escape fraction into intergalactic space of UV radiation, and its reprocessing by an expanding clumpy IGM.
The UVB remains a crucial yet most uncertain input parameters for cosmological simulations of LSS and galaxy formation and for interpreting QSO absorption lines observations.
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HOME DOWNLOADS BIBLIOGRAPHY ABOUT US
CUBA is a radiative transfer code that follows the propagation of hydrogen and
helium Lyman continuum radiation through a partially ionized and clumpy
intergalactic medium. The only sources of ionizing radiation included in CUBA
are star-forming galaxies and quasars.
Contador
CUBACosmic Ultraviolet BAckground
a cosmological 1D radiative transfer code by
Francesco Haardt and Piero Madau
www.ucolick.org/~pmadau/CUBA
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The equation of cosmological radiative transfer describes the timeevolution of the space- and angle-averaged monochromatic intensity Jν:
Cosmological radiative transfer
RT equation must be solved by iterations since
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➔ Poissonian probability of encountering a total optical depth kτ0 is:
Assume random distribution of absorbers in column density and redshift space, then:
Effective optical depth of the IGM
observed must be modeled
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Lyαforest
z=2
z=3.5
z=5
LLS
SLLS
DLA
Prochaska et al. 2009
Quasar absorbers along the LOS
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Cowie et al. 2009
Hopkins et al. 2007Bongiorno et al. 2007
Meiksin 2005
10 keV
2 keV
Intrinsic HXLF: Ueda et al. 2003Silverman et al. 2008
SXLF after absorption: PM et al. 1994
The X-ray properties of the quasar population as a whole are recorded in the cosmic XRB: 1) XRB may play a unique role in regulating the thermodynamics and ionization degree of intergalactic absorbers; 2) Soft X-rays between 0.5 and 0.9 keV are responsible for the highest ionization states of C, N, O; 3) X-rays penetrate regions that are optically thick to UV radiation, providing a source of heating and ionization; 4) Compton scattering of hard XRB photons may be a source of heating for highly ionized low-density intergalactic gas.
QSO emissivity
Type I and II QSOs
SAX
HEAO-1A2 HED
HEAO-1A4 LED
HEAO-1
A4 MED
ROSAT
XMM
XMM
XTE
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Galaxy emissivity
Schiminovich et al 2005 Reddy & Steidel 2009 Bouwens et al 2010
Calzetti et al. 2000
Kewley & Kobulnicky 2007
Rate of H-ionizing photons vs time for SSP
GALEXEVSTARBURST99
FSPSall Salpeter IMF
Z=Z⊙
GALEXEV Z=0.2Z⊙
z=0 EBL
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Kuhlen et al 2011Dwarf galaxy formation with H2-regulated SF
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QSOs
Galaxies
Escape fraction
Inoue et al. 2006
Bolton & Haehnelt 07Becker et al. 07
Faucher-Giguere et al. 08Calverley et al 10
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1) Absorbers are not only sinks but also sources of ionizing radiation: recombinations to ground states of HI, HeI, HeII, HeII Balmer and 2γ-continuum, HeII Lyα
Two important effects
J
x
J
!
0 L
Solve numerically (local radiative transfer) for the photoionization structure of individual absorbers (semi-infinite slab with L=λJ)
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2) besides photoelectric absorption, resonant absorption by H and He Lyman series will produce a sawtooth modulation of the UVB spectrum.
Lyβ
Lyγ
PM & Haardt 2009Haiman et al. 1997Pritchard & Furlanetto 2006
OII SiIV CIII OIII
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HI distribution
cosmological radiative transfer ➔ J
τeff, εrec
QSO/GAL LF SED
J-solution flow chart
ABSORBERS SOURCES
local radiative transfer ➔H/He ionization state
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Building up the UVB (Gal+QSOs) @ z=3
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UVB: quasars only
HM96
HM11
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UVB: quasars + galaxies
QSO
Gal+QSO
Gal SED steeper than QSO ➔ HeII/HI↑
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HeII sawtooth
QSO
Gal+QSO
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HI sawtooth
Gal+QSO
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Reionization @ milliFLOP speed (PM, Haardt, & Rees 1999; Shapiro & Giroux 1987)
QI(t)= volume filling factor of HII regions at t
The reionization equation
QI(t) =! t
0n!(t!)
!nH(t!)"dt# !! t
0QI (t!)
trecdt#
source sink
(no redshifting, ionizing photons assorbed locally). Differentiating:
dQI
dt=
n!
!nH" !QI
trec
simple diff. eq. statistically describes transition from a neutral Universe to a
fully ionized one!Contrary to the static case, cosmological HII regions will always percolate in an expanding universe with constant comoving ionizing emissivity....
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A “minimal reionization model” We have integrated the
reionization equation assuming T=104.3 K and gas clumping
factor CIGM=1+43/z1.71
CIGM=3 @ z=6
NO POPIII !CIGM≡C100 from Pawlik et al. 2009
CHeIII≡CIGM
Reionization is extended
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τe(0,z)x10
Optical depth for e- scattering
WMAP-7 τe=0.088±0.015
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THE END
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