UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
UV Radiative Feedback During UV Radiative Feedback During ReionizationReionization
Andrei MesingerAndrei MesingerPrinceton UniversityPrinceton University
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Current Reionization Constraints at z~6-7Current Reionization Constraints at z~6-7
• WMAP e ~ 0.0870.017 reionization z~11?
Dunkely+2009
Caution:
- integrated measurement
• Ly forest in GP troughs of SDSS QSOs
Fan et al. 2006: xHI ≥ 10-3 and accelerated evolution
Becker et al. 2007: no accelerated evolution
-rise in does not directly translate to rise in xHI (Furlanetto & Mesinger 2009)-analytical density models-differences sensitive to low -extrapolation sensitive to continuum fitting
• Size of Proximity Region: xHI ≥ 0.1
Wyithe & Loeb 2004; Wyithe+ 2004
Combined w/ independent constraints on L and age (Mesinger & Haiman 2004)
Evolution in size (Fan et al. 2006): xHI ~ 10-3
-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 feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Current Reionization Constraints at z~6-7, Current Reionization Constraints at z~6-7, contcont..
• No evolution in Ly emitter (LAE) LFIn isolation: xHI < 0.3 (e.g. Malhotra & Rhoads 2004)
Clustered: xHI < 0.5 (Furlanetto et al. 2006)
• Some evolution in LAE LF (Kashikawa et al. 2006)
• LAE clustering xHI < 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. 2008 disagree with impact on clustering
• Lack of Ly damping wing in z=6.3 GRB
Totani et al. 2006 xHI < 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) xHI> 0.2
Modeling Ly forest in proximity region
(Mesinger & Haiman 2007) xHI > 0.03
- 2 sightlines- patchy reionization likely degrades confidence contours (Mesinger & Furlanetto 2008b)
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Challenges in Modeling Global ProcessesChallenges 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 feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
PhilosophyPhilosophyUse the right tool for the job!
one size DOES NOT fit all!
QuickTime™ and aH.264 decompressor
are needed to see this picture.
Mesinger (2007)
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
OutlineOutline
• Radiative feedback throughout reionization:– advanced stages of reionization and Mmin
– early stages (fossil HII regions around massive stars)
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
MMminmin in Advanced Stages of Reionization 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, Tvir>104 K)
– can extend reionization– early work, z=2 halos with vcir<35km/s completely
suppressed; vcir < 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 feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Systematic approach -> Minimize AssumptionsSystematic approach -> Minimize Assumptions
• We do NOT attempt to self-consistently model reionization
• LARGE parameter space (small knowledge at high-z):– z = 7, 10, 13
– <xHI>
– ionization efficiency, fid (=1 to match z=6 LAE and LBG LFs)
Does UV radiative feedback impact the advanced stages of reionization? Does/How Mmin effectively increase in ionized regions?
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Two Tier ApproachTwo Tier Approach• 1D hydro simulations to model
collapse of gas + dark matter under UVB:
fg(Mhalo, z, J21, zon=14)
• Semi-numerical code (DexM) to model halo, ionization and inhomogeneous flux fields:
J21(x, z, <xH>, fid)
Mesinger & Dijkstra (2008)
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Ionizing UV Flux FieldsIonizing UV Flux Fields
Mesinger & Dijkstra (2008)
flux ∑ L(Mhalo)/r2 e-r/mfp
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Global impactGlobal impact
Mesinger & Dijkstra (2008)
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
MMminmin
• Factor of 10 increase in ionizing efficiency is required to extend suppression by only factor of 2 in mass.
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Being Conservative…Being Conservative…
• No self-shielding mfp = 20 Mpc (the high-end of z<4 LLS extrapolations;
Storrie-Lombardi+ 1994)
• zon = 14 (zre = 11.0 +/- 1.4; Dunkley+ 2008)
– biased halo formation
• No redshift evolution of J21 over zon --> z
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Relic HII RegionsRelic 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 feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
UV Radiative Feedback in Relic HII RegionsUV 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; O’Shea+2005; Abel+2007; ; Ahn & Shapiro 2007; Whalen+2008)
Radiative feedback on subsequent star formation can be:• positive (e- catalyzes H2 formation/cooling channel)
• negative (LW radiation disassociates H2; 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:
JJUVUV = 0 = 0 FlashFlash JJUVUV = 0.08 = 0.08 JJUV UV = 0.8= 0.8Then add LWB of various strengths
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Pretty PicturesPretty Pictures
T(K)10 104
20 h
-1 k
pc
z = 25
JJUVUV = 0.08 = 0.08
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Pretty PicturesPretty Pictures
T(K)10 104
20 h
-1 k
pc
z = 24.9
JJUVUV = 0.08 = 0.08
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Pretty PicturesPretty Pictures
T(K)10 104
20 h
-1 k
pc
z = 24.62
JJUVUV = 0.08 = 0.08
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Pretty PicturesPretty Pictures
T(K)10 104
20 h
-1 k
pc
z = 24
JJUVUV = 0.08 = 0.08
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Pretty PicturesPretty Pictures
T(K)10 104
20 h
-1 k
pc
z = 23
JJUVUV = 0.08 = 0.08
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Pretty PicturesPretty Pictures
T(K)10 104
20 h
-1 k
pc
z = 22
JJUVUV = 0.08 = 0.08
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Pretty PicturesPretty Pictures
T(K)10 104
20 h
-1 k
pc
z = 21
JJUVUV = 0.08 = 0.08
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Pretty PicturesPretty Pictures
T(K)10 104
20 h
-1 k
pc
z = 20
JJUVUV = 0.08 = 0.08
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Physics OutlinePhysics Outline• When the UVB turns on, gas gets ionized and heated to T~104 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~103 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, xH2 ~ few x 10-3, irrespective of the gas density and temperature.
• The pressure-shock begins to dissipate and gas with a newly enhanced H2 abundance starts falling back onto the partially evacuated halo.
• The enhanced H2 abundance allows the infalling gas to cool faster.
-
+
No RT!
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Radial ProfilesRadial ProfilesJJUVUV = 0 = 0JJUV UV = 0.8= 0.8
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Transient FeedbackTransient Feedback
_ FlashFlash JJUVUV = 0.08 = 0.08 JJUVUV = 0.8 = 0.8
Mesinger+ (2006) Mesinger+ (2008)
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Physics Outline (halo embryos)Physics Outline (halo embryos)• When the UVB turns on, gas gets ionized and heated to T~104 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~103 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, xH2 ~ few x 10-3, irrespective of the gas density and temperature.
• The pressure-shock begins to dissipate and gas with a newly enhanced H2 abundance starts falling back onto the partially evacuated halo.
• The enhanced H2 abundance allows the infalling gas to cool faster.
-
+
No RT ok!
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Eventual Positive FeedbackEventual Positive FeedbackJJUVUV = 0 = 0JJUV UV = 0.8= 0.8JJUVUV=0.8, J=0.8, JLWLW=10=10-3-3
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
ConclusionsConclusions
• UV feedback on T>104 K halos NOT strong enough to notably affect bulk of reionization (requires factor of ~100 increase in ionizing efficiencies)
• Likely Mmin ~ 108 Msun 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>104 K halos, with small filling factor tail extending to higher z due to T<104 K halos, likely regulated by LWB??? Late stages maybe slowed down by photon sinks???
• Dynamic range is important in modeling reionization!
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Halo FilteringHalo FilteringMesinger & Furlanetto (2007)
z=8.7 N-body halo field fromMcQuinn et al. (2007)
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Density FieldsDensity FieldsNumerical resultsfrom Trac+2008
z=7
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
Density Fields, cont.Density Fields, cont.Mesinger+ 2009 (in preparation)
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
HII Bubble FilteringHII Bubble FilteringMesinger & Furlanetto (2007)
RT ionization field fromZahn et al. (2007)
UV radiative feedbackUV radiative feedback Ringberg, Germany 24-27. march, 2009Ringberg, Germany 24-27. march, 2009
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