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Radiative Transfer Simulations

The Proximity Effect of LBGs:. Radiative Transfer Simulations. Antonella Maselli, OAArcetri, Firenze, Italy Collaborators: A.Ferrara, M. Bruscoli, S. Marri & R. Schneider. Marri et al 2003, in preparation Bruscoli et al, 2003,MNRAS,343,L45 Maselli et al, 2003,submitted to MNRAS.

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Radiative Transfer Simulations

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  1. The Proximity Effect of LBGs: Radiative Transfer Simulations Antonella Maselli, OAArcetri, Firenze, Italy Collaborators: A.Ferrara, M. Bruscoli, S. Marri & R. Schneider Marri et al 2003, in preparation Bruscoli et al, 2003,MNRAS,343,L45 Maselli et al, 2003,submitted to MNRAS

  2. 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 Japan - Italy Joint Seminar, 2003

  3. OBSERVATIONS: Results • 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 z3 Adelberger et al (2002)

  4. Interpretations for the transparency of the inner region OBSERVATIONS: Results • Observations are biased • SNe Driven-Winds • Local Photoionization 8 bright QSOs at 3.1< z <4.1 431 Lyman Break Galaxies at z3 Adelberger et al (2002)

  5. Bruscoli et al (2002) 398 galaxies identified with a HOP group finding algorithm (Eisenstein & Hut, 1998) OUTFLOWS CANNOT CLEAR THE GAS AROUND GALAXIES AS REQUIRED BY OBSERVATIONS Croft et al(2002) Kollmeier et al(2003) consistent with Numerical Simulations: WINDS Multiphase SPH simulation (Marri et al., 2003; Marri & White, 2002) WINDS UVB (Haardt & Madau 1996) z =3.26 LBOX = 10.5 Mpc h-1 comoving

  6. ?can do the job? } Adelberger et al(2003) Analytical approach Kollmeier et al(2003) Negative answer Numerical approach Croft et al(2002) THE IGM IN THE VICINITY OF GALAXIES HAS BIASED PHYSICAL PROPERTIES LOCAL PHOTOIONIZATION COMMON ASSUMPTION: PHOTONS ESCAPING FROM LBGs HAVE A MEAN FREE PATH EQUAL TO THAT IN THE IGM   240 Mpch-1 FULL CONSISTENT RADIATIVE TRANSFER SIMULATIONS ARE NEEDED TO ANSWER THE QUESTION

  7. V(Fgal/F bkg > 1)  5 % Vbox Rinfluence  0.4Mpc h-1 for a typical galaxy in the simulation 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 Japan - Italy Joint Seminar, 2003

  8. + OUTPUTS • Multiple point sources Ionizing sources • Background (UVB) • Diffuse radiation • from recombinations Time evolution of TEMPERATURE and IONIZATION FRACTIONS inside the simulation volume Maselli et al (2003) Radiative Transfer Simulations: CRASH Multiphase SPH simulation 3-D gas distribution (nH, T, xI) Arbitrary 3-D precomputed cosmological H/He density field 398 galaxies (L  SFR , Starbust99 ) UVB, (Haardt & Madau 1996) Japan - Italy Joint Seminar, 2003

  9. 4 Mpc h-1 4 Mpc h-1 Neutral Hydrogen Fraction 290M  yr -1 NO galaxy SFR 29 M yr -1 Most massive galaxy 8.7 x 1010 M 90M  yr -1 NO galaxy SFR 0.09M  yr -1 Less massive galaxy 9.2 x 108 M Japan - Italy Joint Seminar, 2003

  10. Neutral Hydrogen Fraction NO galaxy SFR 29 Myr -1 SFR 290M yr -1 Most massive galaxy 8.7 x 1010 M 4 Mpc h-1 NO galaxy SFR 0.09M yr -1 SFR 90M yr -1 Less massive galaxy 4 Mpc h-1 9.2 x 108 M Japan - Italy Joint Seminar, 2003

  11.  1 Mpc h-1 comoving Neutral Hydrogen Fraction along LOS across galaxies SFR  29 Myr -1 SFR  290M yr -1 highest mass galaxy 8.7 x 1010 M UVB SFR from SPH SFR boosted Log (xHI) SFR 0.09 M yr -1 SFR 90 Myr-1 lowest mass galaxy 9.2 x 108 M along x along y along z Japan - Italy Joint Seminar, 2003

  12. Mean Ly  Transmitted Flux: UVB & Galaxies The UV emission by galaxies has little effect on the mean Ly trasmissivity of the IGM <F> mean Flux Ly trasmissivity r los/galaxy separation for 398 galaxies Japan - Italy Joint Seminar, 2003

  13. Regions around high mass galaxies are less transparent than those around normal galaxies because of the higher mean density RED CURVE Adelberger etal , 2003 UVB only UVB + Galaxies, SFR from MSPH UVB + Galaxies, boosted SFR 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 GREEN CURVES Mean Ly Transmitted Flux: High Mass Galaxies only <F> mean Flux Ly trasmissivity r los/galaxy separation for 9 galaxies with M > 2 x 1010 M Japan - Italy Joint Seminar, 2003

  14. Regions around low mass galaxies are more transparent than those around normal galaxies due to the lower mean density RED CURVE Adelberger etal, 2003 UVB only UVB + Galaxies, SFR from MSPH UVB + Galaxies, boosted SFR The local photoionization could be significant if such galaxies have SFR higher than 50 M yr -1 GREEN CURVE 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  Japan - Italy Joint Seminar, 2003

  15. CONCLUSIONS 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 • HI transparency close to LBGs cannot be explained by • simulated winds (3 different independent results) Problem with SPH shock treatment ? 2. Local Photoionization can partially explain the data if 3. Data could be biased (poor statistics; opposite trend observed at lower redshift)

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