Ewald Puchwein KICC / IoA, University of Cambridge

Transcription

1 Constent modelling of cosmic UV background and rmal/ioniation htory of IGM and its implications for AGN contribution to reioniation Ewald Puchwein KICC / IoA University of Cambridge collaborators: Francesco Haardt Martin Haehnelt Piero Madau

2 The epoch of reioniation time Loeb 26 cold hot 11 Stars? AGN? 6 CMB cosmic dark ages first galaxies and AGN reioniation today

3 Neutral fraction with homogeneous UVB (using Haardt & Madau 212) Planck neutral hydrogen fraction Haardt& Madau 212 equilibrium. Haardt& Madau 212 non-equilibrium Puchwein et al. 215

4 IGM temperature with homogeneous UVB (using Haardt & Madau 212) T [K] HM212 equilibrium HM212 non-equilibrium modifed HM1996 equilibrium Becker et al. 211 g 1 non-eq. Boera et al. 214 recalibrated g 1 non-eq. Boera et al. 214 original g 1 non-eq. Becker et al. 211 g 1 eq. Boera et al. 214 g 1 eq. Bolton et al. 212 Bolton et al. 214 Schaye et al Puchwein et al. 215

5 Too early reioniation in simulations with Haardt & Madau 212 Onorbe et al. 217 re 12. Zoom-in of quasars + galaxies cosmic background spectrum dshifts and 8. showing sawtooth modulation of galactic flux between and 89 and 13 Å produced by resonant absorption e Lyman series of intergalactic H i. Theverticalthinlinesindicate tions of H i Lyα and Lyman limit. The dashed line shows same trum without sawtooth for comparon. ping factor of ionied hydrogen. Differentiation yields reioniation equation of Paper III expectation from emsivity: dq H ii dt ṅion n H Q H ii t rec (64) its equivalent for expanding He iii regions simulation with Haardt & Madau 212 UVB

6 What going wrong? assumed ioniing emsivity UVB model by integrating cosmological radiative transfer equation ( t νh ) J ν +3HJ ν cκ ν J ν + c ν 4π ϵ ν observed column density dtribution effective photoioniation and photoheating rates dq H ii dt ṅion n H Q H ii t rec hydro simulation reioniation htory

7 What going wrong? assumed ioniing emsivity observed column density dtribution (extrapolated to ~15) UVB model by integrating cosmological radiative transfer equation ( t νh ) J ν +3HJ ν cκ ν J ν + c ν 4π ϵ ν effective photoioniation and photoheating rates dq H ii dt ṅion n H Q H ii t rec hydro simulation reioniation htory

8 Z New treatment of for ioniing photons in UVB modelling in Haardt & Madau 212: empirical absorber model (observed column densities at <6) ( o o ) Z o d Z 1 dn HI f(n HI )(1 e c ) Poson dtributed absorbers with optical depth τ c (ν ) N H i σ H i (ν )+N He i σ He i (ν )+N He ii σ He ii (ν )

9 ompared to HM12 we slightly modify some of on mean free path expected when percolatto a radiation evolution i.e.small we do not force dtributio n i.e. we do not force dtribution to e ective mimic basically irrelevant for values ution of compare to Table 1 of HM12). At high dtribuarameters in order to better match new observaually lower than verlap during reioniation. The point was of Q. modelled ncrease tion above H I reioniation 4 rede. Puchwein F. Haardt M. Haehnelt sudden increase in above H I re e suddenininas a simple extrapolation of low- onstraints (Prochaska et al. 214 seethat Table 1 and modified tion. The basic With above prescriptions vies & Furlanetto (214) who showed te however that in our new formalm value of shift. Note however that in our new formal hen percolatevolution i.e. we do not force dtribution to mimic tooftable 1 of HM12). At high dtribuerse mean n: re sources gives re to a radiation tive basically irrelevant for small values e ective basically irrelevant f he point was sudden increase in above H I reioniation red Z odelled as aintensity simple extrapolation of low- Absorbers class log (NHI /cm GM embedding e-averaged actually lower than of new Q. formalm value of showed that our shift. Note however that in ( ) d Q tral component HeIII ( ) n i.e. we do prescriptions not force dtribution to mimic 1 ed by solving RT equation. The basic h above modified d With above prescriptions a radiation Ly forest 1116mod basically irrelevant for e ective small values usly dtributed ncrease in above H I reioniation red pre-reioniation Universe mean y lower than n: of Q. (7) +[Q ( ) of QHeIII ( )] al.new ote however that our formalm HIIvalue Z in in Puchwein et 218: Z nated by still neutral IGM embedding d 2 n. The basic for small sider in eq. 2 a With above prescriptions modified tive basically irrelevant values ( ) d Q ( ) HeIII regions ( ) d QHeIII ( ) ions. which 1 that atmean lowcompletely n:neutral component e Such in d d + 1 QHII ( ). fully ionied ting in case d 3 im-of a continuously dtributed Z hydrogen Mconstraints embedding LLSsneutral regions and HeI h above prescriptions modified (7) QHeIII ( ) time high- +[QHII ( ) regions Q ( )] HeIII ( ) d component +[Q ( ) Q ( )] HeIII For fully ioned IGM ( one 1 ) we have 1 usual HII d 2 have been reionied d niform neutralled us to consider in eq. 2 a ations above dtributed e ective (see eq. 3): SLLSs Z rmconstrain 2.3. low tailored +in 1suchQHII 19.5 Z ( ) that a way at ) QHII ( ) +[QHII ( ) QHeIII (c )] + 1 (7) ( ioniation ) d QHeIIId( 3 3 d matches observational constraints imd d 2 dn f (N )(1 e ) (8) 1 HI HI er in eq. These 2a mployed. d 1 usual forest while same time high- DLAs fully ioned ( one 1 ) we have fully ioned at low atigm + natcuba as defor IGM ( one 1 )21.55 we 1 Q ( ). HII (7) +[Q ( ) Q ( )] where continuum optical depth through an individual 2.3 HeIII HII oaches that expected (see eq. 3): in a uniform neutral 2 d nstraints im3 ar approach has d e ective (see eq. 3): cloud given by eq. 4. c Z ce16) mean density. We furr constrain high- and more Z usual where ioned In regions H ioned and He single ioned For fully IGM ( one 1 ) we have c of dtribution of intergalactic +dn1hi f Q ( (NHII ))(1 e.) (8) 1. Parameters UVB to earlier be constent with ioniation HI Table a d on an orm neutral dn f (N )(1 e d d 1 ( one 2 ) given by 3 HI HI e ective (see eq. 3): 1 plied by emsivity employed. These d onstrain Z Z individual eehave continuum optical depth through an c d` lume filling facbeen implemented in CUBA as fully ioned IGM ( one 1 ) we have usual HI f (Ndeioniation dn )(1 e ) + n ( HI He continuum HeII c ) where optical depth 3 ) through dn f (N )(1 e ) (8) Finally in fully neutral IGM ( one HI HI d d 2 given by eq. 4. he assumed ion-eq. wing. We note that has (see 3):a similar approach oyed. These d 1 cloud c given by eq. (9)4. tion (for details egions where H ioned and He single ioned Z posed as bydeonorbe et al. (216) regions where and more d` d` UBA In H ioned and He i where d`/d line element in a Friedmann cosmology n ( ) + n ( ) continuum c where optical depth through an individual H HI He HeI ) given by 3 dn e ) (8) dau & Fragos (217) based on an earlier d d d HI f (N HI )(1 pproach has and n He He density at cosmic In consid- given by ( onemean. 2 ) d 1 cloud Z c given by eq. 4. al. (213). d` 6)etand more(5) n HeII hydrogen density at cosmic mean. N and N ofsingle aqcloud ZHe HI columns ered environment c where HeI In regions where H ioned and ioned dq n ion pute dn f (NHIoptical )(1 evolume ) through + n filling ( individual ) HIevolution He HeII he continuum depth an c of fac an of a given be computed ioning ravolume fractions fromnioniing photon budget adopting ) n (ionied an earlier d HI should dn f (N )(1 e ) + n He ( one 2 ) given by dt n HI t rec HI New treatment of for ioniing photons in UVB modelling

10 Mean free path for ioniing photons mean free path at 912 Å [proper Mpc] HM12 fiducial neutral region O Meara et al. 213 Prochaska et al. 29 Worseck et al Puchwein et al. 218

11 Photoioniation rates with new effective 1 12 HI photoioniation rate [s 1 ] Haardt & Madau 212 fiducial emsion rate H I ioniing photons per H atom fiducial Becker and Bolton 213 Calverley Puchwein et al. 218

12 Thermal and ioniation state of IGM in simulations with new UVB ionied fraction HM12 HII fraction in simulation HM12 expected HII fraction HM12 HeIII fraction in simulation HM12 expected HeIII fraction fiducial HII fraction in simulation fiducial expected HII fraction fiducial HeIII fraction in simulation fiducial expected HeIII fraction inconstent in HM12 T [K] 15 1 HM12 fiducial constent in new model Puchwein et al. 218

13 Rates for codes assuming ioniation equilibrium. 15 HM12 fiducial eq.-eq. fiducial T [K] Puchwein et al. 218

14 Using new UVB model rate files

15 IGM temperature in scenarios with a large AGN contribution AGN-dominated model (Madau & Haardt 215) stars in AGN-assted model AGN stars AGN in fiducial model Puchwein et al. 218

16 IGM temperature at mean density in scenarios with a large AGN contribution Puchwein et al. 218

17 IGM temperature at density where it measured in scenarios with a large AGN contribution 3 density () T ( ()) [K] AGN-dominated AGN-assted AGN-assted f escheii.5 AGN-assted a UV 2 fiducial model fiducial model T ( ()) in simulation fiducial eq.-eq. Becker et al Puchwein et al. 218

18 HeII Lyman-alpha forest effective optical depth in scenarios with a large AGN contribution He II effective optical depth 1 1 AGN-dominated AGN-assted AGN-assted f escheii.5 AGN-assted a UV 2 fiducial fiducial eq.-ion. Syphers & Shull 214 Worseck et al. 216 Zheng et al. 24 Fechner et al. 26 Reimers et al. 25 H effective optical depth Puchwein et al. 218

19 Summary: New UVB model and rmal evolution (most) previous UVB models inconstent reioniation htories and heating in cosmological simulations can be fixed with a different prescription of IGM during reioniation new rates are available (including equivalent rates for codes assuming ioniation equilibrium) models with a large AGN contribution to H I reioniation are in tension with IGM temperature measurements at > 3 and observed HeII optical depths