Andr eas PawlikLeiden Univer sit y

PhD super visor : J oop Schaye

Claudio Dalla VecchiaHuub Röttgering

Andreas Pawlik, Leiden University

• I nt r oduct ion

• Ther mal f eedback (posit ive / negat ive)

• TRAPHI C - r adiat ive t r ansf er f or SPH

Andreas Pawlik, Leiden University

r edshif t z 6 0

1 13.7 Gyr

Fir st st ar s

Recombinat ion

Reionizat ion

Andreas Pawlik, Leiden University

• Gadget -2(Springel ‘05)

• Def ault r uns: L = 6.25 Mpc/ h, N = 2 x 2563

• St ar f or mat ion (Schaye & Dalla Vecchia ‘07)

• UV backgr ound (z < 9) (Haardt & Madau ’01; cooling tables: Wiersma et al. ’08)

Andreas Pawlik, Leiden University

10log

-1.0 0.0 1.0 2.0

z = 9

3.125 Mpc / h

Andreas Pawlik, Leiden University

z = 9

10log

-1.0 0.0 1.0 2.0

3.125 Mpc / h

z = 6

Andreas Pawlik, Leiden University10log

-1.0 0.0 1.0 2.0

z = 9 z = 9r ef er ence r eheat ing f or z < 9

3.125 Mpc / h 3.125 Mpc / h

Andreas Pawlik, Leiden University10log

-1.0 0.0 1.0 2.0

3.125 Mpc / h

z = 6

3.125 Mpc / h

z = 6r ef er ence r eheat ing f or z < 9

Andreas Pawlik, Leiden University

• Smoot hing of f luct uat ions -> lower ing of r ecombinat ion r at e-> r educes r equir ed st ar f or mat ion r at e-> posit ive f eedback

• Phot o-evapor at ion of low-mass halos-> r educes st ar f or mat ion r at e->negat ive f eedback

AP, J. Schaye & E. van Scherpenzeel (arXiv:0807.3963)

Andreas Pawlik, Leiden University

Andreas Pawlik, Leiden University

• Dalla Vecchia & Schaye (2008) (Springel & Hernquist ‘03)

• v = 600 km s-1

• Mass loading = 2

I solat ed galaxy, 1012 Msun/ hDalla Vecchia & Schaye (2008)

Andreas Pawlik, Leiden University

Andreas Pawlik, Leiden University

Andreas Pawlik, Leiden University

wwS

,

hhS

,

whwhS

,

hwwh SSS

)(/ hwwh SSS

?

Andreas Pawlik, Leiden University

Andreas Pawlik, Leiden University

• Bot h r eheat ing and super nova f eedback r educe t he SFR -> negat ive f eedback

• Reheat ing and super nova f eedback mut ually st r engt hen each ot her

• Ef f ect incr eases wit h r esolut ion

AP & J. Schaye (in preparation)

Andreas Pawlik, Leiden University

• Lar ge r epr esent at ive volumes(cosmic var iance, long wavelengt hs)

• High r esolut ion(f ir st galaxies, at omic cooler s ~108 Msun)

• Accur at e gas dist r ibut ion (r ecombinat ion r at e)

• Many sour ces(st ellar and r ecombinat ion r adiat ion)

Andreas Pawlik, Leiden University

• Radiat ive t r ansf er on hydr odynamics (vs. N-body/ semi-analyt ics)

• Spat ially adapt ive(vs. unif or m mesh)

• Par allel on dist r ibut ed memor y(vs. ser ial; par allel on shar ed memor y)

• Avoid scaling wit h # sour ces (vs. linear scaling)

TRAPHI C – r adiat ive t r ansf er f or SPH

Andreas Pawlik, Leiden University

•Adapt ive: Dir ect ly on SPH par t icles

•Par allel: Tr anspor t employs t he SPH par t icle-neighbor scheme

•Ef f icient : Comput at ion t ime independentof # sour ces

Andreas Pawlik, Leiden University

• Spat ial r esolut ion: # SPH neighbor s• Angular r esolut ion: # Cones• Tempor al r esolut ion: Clocks• Comput at ion t ime: Phot on packet mer ging

AP & J. Schaye (2008), MNRAS 389, 651

Andreas Pawlik, Leiden University

• Reionizat ion simulat ions r equir e t ailor ed appr oaches f or solving t he r adiat ivet r ansf er pr oblem

• TRAPHI C – r adiat ive t r ansf er f or SPHadapt ive, par allel, ef f icient

AP & J. Schaye (2008), MNRAS 389, 651

Andreas Pawlik, Leiden University

• Ther mal coupling r equir es mult i-f r equency t r eat ment

• Example: St ar wit h blackbody spect r um T = 105 K in homogeneous hydr ogen-only medium init ially neut r al and at 100 K

neut r al & cold

ionized & hot

Andreas Pawlik, Leiden University

Nor malized dist ance t o st ar

neut r al /ionizedf r act ion

Temp.

blackbodyTbb = 105 K

t = t rec

Andreas Pawlik, Leiden University

neut r al /ionizedf r act ion

Temp.

Nor malized dist ance t o st ar

blackbodyTbb = 105 K

t = t rec