UV radiative feedbackRingberg, Germany march, 2009 UV Radiative Feedback During Reionization Andrei Mesinger Princeton University

UV radiative feedbackRingberg, Germany march, 2009 Current Reionization Constraints at z~6-7 WMAP e ~ reionization z~11? Dunkely+2009 Caution: - integrated measurement Ly forest in GP troughs of SDSS QSOs Fan et al. 2006: x HI and accelerated evolution Becker et al. 2007: no accelerated evolution -rise in does not directly translate to rise in x HI (Furlanetto & Mesinger 2009) -analytical density models -differences sensitive to low -extrapolation sensitive to continuum fitting Size of Proximity Region: x HI 0.1 Wyithe & Loeb 2004; Wyithe Combined w/ independent constraints on L and age (Mesinger & Haiman 2004) Evolution in size (Fan et al. 2006): x HI ~ extremely model-dependent -cannot directly read size or evolution of proximity region from spectra! (Mesinger+ 2004; Mesinger & Haiman 2004; Bolton & Haehnelt 2007ab; Maselli+ 2006, 2007)

UV radiative feedbackRingberg, Germany march, 2009 Current Reionization Constraints at z~6-7, cont. No evolution in Ly emitter (LAE) LF In isolation: x HI < 0.3 (e.g. Malhotra & Rhoads 2004) Clustered: x HI < 0.5 (Furlanetto et al. 2006) Some evolution in LAE LF (Kashikawa et al. 2006) LAE clustering x HI < 0.5 (McQuinn et al. 2007) Caution: -L M unknown -very model dependent -drop due to density and halo evolution? (Dijkstra et al. 2007) -reionization signature should be a flat suppression (Furlanetto et al. 2006; McQuinn et al. 2007; Mesinger & Furlanetto 2008a) -Iliev et al disagree with impact on clustering Lack of Ly damping wing in z=6.3 GRB Totani et al x HI < 0.2 -no statistical significance (McQuinn et al. 2008; Mesinger & Furlanetto 2008b) Detection of Ly damping wing in QSOs Sharp decline in flux (Mesinger & Haiman 2004) x HI > 0.2 Modeling Ly forest in proximity region (Mesinger & Haiman 2007) x HI > sightlines - patchy reionization likely degrades confidence contours (Mesinger & Furlanetto 2008b)

UV radiative feedbackRingberg, Germany march, 2009 Challenges in Modeling Global Processes Virtually nothing is well-known at high-z --> enormous parameter space to explore Dynamic range required is enormous: single star --> Universe Be systematic!

UV radiative feedbackRingberg, Germany march, 2009 Philosophy Use the right tool for the job! one size DOES NOT fit all! Mesinger (2007)

UV radiative feedbackRingberg, Germany march, 2009 Outline Radiative feedback throughout reionization: –advanced stages of reionization and M min –early stages (fossil HII regions around massive stars)

UV radiative feedbackRingberg, Germany march, 2009 M min in Advanced Stages of Reionization Ionizing UVB suppresses gas content of low-mass galaxies (e.g. Efstathiou 1992; Shapiro+1994; Thoul & Weinberg 1996; Hui & Gnedin 1997; Gnedin 2000) How important is this negative feedback during reionization? (we focus on atomically-cooled halos, T vir >10 4 K ) –can extend reionization –early work, z=2 halos with v cir <35km/s completely suppressed; v cir < 100km/s partially suppressed –NOT THIS SIMPLE! Not instantaneous; high-z mediated by more compact profiles, increased cooling efficiencies, shorter exposure times (Kitayama & Ikeuchi 2000; Dijkstra+ 2004) Can we draw any general conclusions about this exceedingly complex problem?

UV radiative feedbackRingberg, Germany march, 2009 Systematic approach -> Minimize Assumptions We do NOT attempt to self-consistently model reionization LARGE parameter space ( small knowledge at high-z): –z = 7, 10, 13 – –ionization efficiency, fid (=1 to match z=6 LAE and LBG LFs) Does UV radiative feedback impact the advanced stages of reionization? Does/How M min effectively increase in ionized regions?

UV radiative feedbackRingberg, Germany march, 2009 Two Tier Approach 1D hydro simulations to model collapse of gas + dark matter under UVB: f g (M halo, z, J 21, z on =14) Semi-numerical code (DexM) to model halo, ionization and inhomogeneous flux fields: J 21 (x, z,, fid ) Mesinger & Dijkstra (2008)

UV radiative feedbackRingberg, Germany march, 2009 Ionizing UV Flux Fields Mesinger & Dijkstra (2008) flux L(M halo )/r 2 e -r/ mfp

UV radiative feedbackRingberg, Germany march, 2009 Global impact Mesinger & Dijkstra (2008)

UV radiative feedbackRingberg, Germany march, 2009 M min Factor of 10 increase in ionizing efficiency is required to extend suppression by only factor of 2 in mass.

UV radiative feedbackRingberg, Germany march, 2009 Being Conservative… No self-shielding mfp = 20 Mpc (the high-end of z<4 LLS extrapolations; Storrie-Lombardi ) z on = 14 (z re = /- 1.4; Dunkley ) –biased halo formation No redshift evolution of J 21 over z on --> z

UV radiative feedbackRingberg, Germany march, 2009 Relic HII Regions Short lived, massive Pop III stars carve out ionized bubbles, then turn off. Structure formation is highly biased at high-z; what happens inside these relic HII regions? ? ?

UV radiative feedbackRingberg, Germany march, 2009 UV Radiative Feedback in Relic HII Regions Problem is very complex and can benefit from both semi-analytic (e.g. Haiman et al. 1996; Oh & Haiman 2003; MacIntyre et al. 2005), and numerical studies (e.g. Machacek+2003; Ricotti+2002; Kuhlen & Madau 2005; OShea+2005; Abel+2007; ; Ahn & Shapiro 2007; Whalen+2008) Radiative feedback on subsequent star formation can be: positive (e - catalyzes H 2 formation/cooling channel) negative (LW radiation disassociates H 2 ; radiative heating can photoevaporate small halos or leave gas with tenacious excess entropy) We attempt to quantify the feedback effects from a UVB consistent with that expected from an early Pop III star using the cosmological AMR code, Enzo. Fiducial runs: J UV = 0 Flash J UV = 0.08 J UV = 0.8 Then add LWB of various strengths

UV radiative feedbackRingberg, Germany march, 2009 Pretty Pictures T(K) h -1 kpc z = 25 J UV = 0.08

UV radiative feedbackRingberg, Germany march, 2009 Pretty Pictures T(K) h -1 kpc z = 24.9 J UV = 0.08

UV radiative feedbackRingberg, Germany march, 2009 Pretty Pictures T(K) h -1 kpc z = J UV = 0.08

UV radiative feedbackRingberg, Germany march, 2009 Pretty Pictures T(K) h -1 kpc z = 24 J UV = 0.08

UV radiative feedbackRingberg, Germany march, 2009 Pretty Pictures T(K) h -1 kpc z = 23 J UV = 0.08

UV radiative feedbackRingberg, Germany march, 2009 Pretty Pictures T(K) h -1 kpc z = 22 J UV = 0.08

UV radiative feedbackRingberg, Germany march, 2009 Pretty Pictures T(K) h -1 kpc z = 21 J UV = 0.08

UV radiative feedbackRingberg, Germany march, 2009 Pretty Pictures T(K) h -1 kpc z = 20 J UV = 0.08

UV radiative feedbackRingberg, Germany march, 2009 Physics Outline When the UVB turns on, gas gets ionized and heated to T~10 4 K. The temperature increase sets-off an outward moving pressure shock in the cores of halos, where density profiles have already steepened. This pressure shock smoothes out the gas distribution and leads to a decrease in gas density in the cores of halos. Once the UVB is turned off, the gas rapidly cools to T~10 3 K through a combination of atomic, molecular hydrogen and Compton cooling. This temperature approximately corresponds to the gas temperature at the virial radius of such a proto-galactic, molecularly-cooled halo, thus effectively neutralizing the impact of temperature change on feedback. A large amount of molecular hydrogen is produced, x H2 ~ few x 10 -3, irrespective of the gas density and temperature. The pressure-shock begins to dissipate and gas with a newly enhanced H 2 abundance starts falling back onto the partially evacuated halo. The enhanced H 2 abundance allows the infalling gas to cool faster. - + No RT!

UV radiative feedbackRingberg, Germany march, 2009 Radial Profiles J UV = 0 J UV = 0.8

UV radiative feedbackRingberg, Germany march, 2009 Transient Feedback _ Flash J UV = 0.08 J UV = 0.8 Mesinger+ (2006)Mesinger+ (2008)

UV radiative feedbackRingberg, Germany march, 2009 Physics Outline (halo embryos) When the UVB turns on, gas gets ionized and heated to T~10 4 K. The temperature increase sets-off an outward moving pressure shock in the cores of halos, where density profiles have already steepened. This pressure shock smoothes out the gas distribution and leads to a decrease in gas density in the cores of halos. Once the UVB is turned off, the gas rapidly cools to T~10 3 K through a combination of atomic, molecular hydrogen and Compton cooling. This temperature approximately corresponds to the gas temperature at the virial radius of such a proto-galactic, molecularly-cooled halo, thus effectively neutralizing the impact of temperature change on feedback. A large amount of molecular hydrogen is produced, x H2 ~ few x 10 -3, irrespective of the gas density and temperature. The pressure-shock begins to dissipate and gas with a newly enhanced H 2 abundance starts falling back onto the partially evacuated halo. The enhanced H 2 abundance allows the infalling gas to cool faster. - + No RT ok!

UV radiative feedbackRingberg, Germany march, 2009 Eventual Positive Feedback J UV = 0 J UV = 0.8 J UV =0.8, J LW =10 -3

UV radiative feedbackRingberg, Germany march, 2009 Conclusions UV feedback on T>10 4 K halos NOT strong enough to notably affect bulk of reionization (requires factor of ~100 increase in ionizing efficiencies) Likely M min ~ 10 8 M sun throughout most of reionization after minihalos no longer dominate In early relic HII regions, feedback can be both + and -, but is transient; eventual + feedback is interesting, but can be suppressed with modest values of LWB Natural timescale for significant part of reionization is the growth of the collapsed fraction in T>10 4 K halos, with small filling factor tail extending to higher z due to T<10 4 K halos, likely regulated by LWB??? Late stages maybe slowed down by photon sinks??? Dynamic range is important in modeling reionization!

UV radiative feedbackRingberg, Germany march, 2009 Halo Filtering Mesinger & Furlanetto (2007) z=8.7 N-body halo field from McQuinn et al. (2007)

UV radiative feedbackRingberg, Germany march, 2009 Density Fields Numerical results from Trac+2008 z=7

UV radiative feedbackRingberg, Germany march, 2009 Density Fields, cont. Mesinger (in preparation)

UV radiative feedbackRingberg, Germany march, 2009 HII Bubble Filtering Mesinger & Furlanetto (2007) RT ionization field from Zahn et al. (2007)

UV radiative feedbackRingberg, Germany march, 2009 Cool PR Movie DexM public release available at