Download - Radiative Transfer Simulations
Radiative Transfer Simulations
The Proximity Effect of LBGs:
Antonella Maselli, OAArcetri, Firenze, Italy
Collaborators: A.Ferrara, M. Bruscoli, S. Marri & R. SchneiderMarri et al 2003, in preparationBruscoli et al, 2003,MNRAS,343,L45Maselli et al, 2003,submitted to MNRAS
Japan - Italy Joint Seminar, 2003
Theoretical Expectations
The physical properties of IGM close to galaxies can be studied through the statistics of absorption lines associated with foreground galaxies in QSOs spectra
Predictions:
• HIGHER NUMBER OF STRONG Ly ABSORPTION LINES• LOWER MEAN Ly TRANSMITTED FLUX at smaller l.o.s./galaxy impact parameters
• 8 bright QSOs at 3.1< z <4.1
• 431 Lyman Break Galaxies at z3
OBSERVATIONS: Results
Adelberger et al (2002)
• LBGs are associated with HI
overdensities at scales 1 Mpc < r < 7 Mpc
• LBGs are associated with HI
underdensities at scales < 1Mpc
• 8 bright QSOs at 3.1< z <4.1
• 431 Lyman Break Galaxies at z3
OBSERVATIONS: Results
Adelberger et al (2002)
Interpretations for the transparency of the inner
region
• Observations are biased
• SNe Driven-Winds
• Local Photoionization
Numerical Simulations: WINDS
WINDSUVB (Haardt & Madau 1996)
z =3.26
LBOX = 10.5 Mpc h-1 comoving
Multiphase SPH simulation(Marri et al., 2003; Marri & White, 2002)
consistent withCroft et al (2002)
Kollmeier et al (2003)
Bruscoli et al (2002)
398 galaxies identified with a HOP group finding algorithm (Eisenstein & Hut, 1998)
OUTFLOWS CANNOTCLEAR THE GAS AROUND GALAXIES
AS REQUIRED BY OBSERVATIONS
COMMON ASSUMPTION:
PHOTONS ESCAPING FROM LBGs HAVE A MEAN FREE PATH EQUAL TO THAT IN THE IGM
240 Mpc h-1
LOCAL PHOTOIONIZATION?can do the job?
Croft et al (2002)
Kollmeier et al (2003)
Adelberger et al (2003) Analytical approach
Numerical approach
}Negative answer
THE IGM IN THE VICINITY OF GALAXIES HAS BIASED PHYSICALPROPERTIES
FULL CONSISTENT RADIATIVE TRANSFER SIMULATIONS ARE NEEDED TO ANSWER THE QUESTION
Japan - Italy Joint Seminar, 2003
Sphere of influence of a typical galaxy
Local photoionization can be significant in determining the ionization state of the
IGM where : Fgal/F bkg > 1
V(Fgal/F bkg > 1) 5 % Vbox
Rinfluence 0.4 Mpc h-1 for a typical galaxy
in the simulation
Japan - Italy Joint Seminar, 2003
+Ionizing sources
• Multiple point sources• Background (UVB)• Diffuse radiation from recombinations
Radiative Transfer Simulations: CRASH Maselli et al (2003)
Arbitrary 3-D precomputed cosmological H/He density field
Multiphase SPH simulation
3-D gas distribution (nH, T, xI)
398 galaxies (L SFR , Starbust99 )
UVB, (Haardt & Madau 1996)
Time evolution of TEMPERATURE
and IONIZATION FRACTIONS
inside the simulation volume
OUTPUTS
Japan - Italy Joint Seminar, 2003
Neutral Hydrogen Fraction
90 M yr -1SFR 0.09 M yr -1
290 M yr -1
9.2 x 108 M
8.7 x 1010 M
Less massive galaxy
NO galaxy
4 M
pc h
-14
Mpc
h-1
NO galaxy SFR 29 M yr -1
Most massive galaxy
Japan - Italy Joint Seminar, 2003
Neutral Hydrogen Fraction
SFR 90 M yr -1
SFR 29 M yr -1
SFR 0.09 M yr -1
SFR 290 M yr -1
9.2 x 108 M
8.7 x 1010 M
Most massive galaxy
Less massive galaxy
NO galaxy
NO galaxy
4 M
pc h
-14
Mpc
h-1
Japan - Italy Joint Seminar, 2003
Neutral Hydrogen Fraction along LOS across galaxies
SFR 290 M yr -1
Log
(x H
I) UVB
SFR from SPHSFR boosted
along x along y along z
1 Mpc h-1 comoving
SFR 29 M yr -1
8.7 x 1010 M
SFR 0.09 M yr -1 SFR 90 M yr-1 lowest mass galaxy
highest mass galaxy
9.2 x 108 M
Japan - Italy Joint Seminar, 2003
Mean Ly Transmitted Flux: UVB & Galaxies
<F> mean Flux Ly trasmissivity r los/galaxy separation for 398 galaxies
The UV emission by galaxies has little effect on
the mean Ly trasmissivity of the IGM
Japan - Italy Joint Seminar, 2003
<F> mean Flux Ly trasmissivity r los/galaxy separation for 9 galaxies with M > 2 x 1010 M
Mean Ly Transmitted Flux: High Mass Galaxies only
Regions around high mass galaxies are less transparent than those around normal galaxies because of the higher mean densityR
ED
CU
RV
E
The local photoionization produced by high mass galaxies can significantly clear the HI, only if such galaxies have very high star formation rates
(SFR > 100 M yr –1); still in this case is not able to explain the observations
GR
EEN
CU
RV
ES
UVB only
UVB + Galaxies, boosted SFR
UVB + Galaxies, SFR from MSPH
Adelberger etal , 2003
Japan - Italy Joint Seminar, 2003
Mean Ly Transmitted Flux: Low Mass Galaxies only
<F> mean Flux Ly trasmissivity r los/galaxy separation for
9 galaxies with M < 9 x 108 M
Regions around low mass galaxies are more transparent than thosearound normal galaxies due to thelower mean densityR
ED
CU
RV
E
The local photoionization could be significant if such galaxies have SFR higher than
50 M yr -1G
REEN
CU
RV
E
UVB only
UVB + Galaxies, SFR from MSPH
UVB + Galaxies, boosted SFR
Adelberger etal, 2003
2. Local Photoionization can partially explain the data if
CONCLUSIONS1. HI transparency close to LBGs cannot be explained by simulated winds (3 different independent results)
3. Data could be biased (poor statistics; opposite trend observed at lower redshift)
LBGs are massive galaxies
(very high SFR, 100-300 M/yr)
LBGs are low mass galaxies
(lower SFR > 50 M /yr)
DWARF STAR FORMING GALAXIES
Sommerville et al 1998, Dejaques et al 2003
Problem with SPH shock treatment ?