Evidence for Feedback in the IGM at High Redshift Barlow (CIT), Becker (CIT), Boksenberg(IoA), Sargent (CIT), Simcoe (MIT), Rauch (OCIW) (based on QSO absorption line data from Keck HIRES, ESI and LRIS)

How does the undisturbed IGM look ? A cosmic web of baryons formed mainly by gravitational instability Main observational manifestation: the Lyman alpha forest Cen & Ostriker et al Keck HIRES

Interactions between Galaxies and the IGM Galaxies accrete gas (infall velocities ~ 100 km/s) merge (approaching c.o.m. with velocities ~ 200km/s) interact tidally, lose gas by ram pressure stripping move about, stir and heat the IGM ( T ~10^7 K) may have strong winds (outflows w. many 100 km/s) chemically enrich the IGM produce ionizing radiation accrete gas (infall velocities ~ 100 km/s) merge (approaching c.o.m. with velocities ~ 200km/s) interact tidally, lose gas by ram pressure stripping move about, stir and heat the IGM ( T ~10^7 K) may have strong winds (outflows w. many 100 km/s) chemically enrich the IGM produce ionizing radiation z=4 z=3 z=1.8 Boxsize 2 Mpc comov; vc=200km/s; Steinmetz (sim.)

gas phases in a hypothetical large scale filament 100 kpc

Observable Effects 1.Metal enrichment: how much, when, how ? 2.Ionization: stellar/AGN ? 3.Signatures of in/outflows 4.Bulk motion and turbulence 5.Accretion vs winds 1.Metal enrichment: how much, when, how ? 2.Ionization: stellar/AGN ? 3.Signatures of in/outflows 4.Bulk motion and turbulence 5.Accretion vs winds

By z~3 the IGM is widely enriched with metals (C,O) Lognormal distribution with – –describes metallicity of about 50% of the mass and 5% of the volume of the universe – –probes down to overdensities > 1.6, i.e., to the edge of large scale filaments (Simcoe, Sargent & Rauch 2004) See talk by Joop Schaye Latest results (Simcoe et al 2004):

The ‘Ultimate Closed Box’ model (Simcoe et al 2004) Universal chemical evolution: treat galaxies as sources of metals and the IGM as the mass reservoir requires that on average more than 14 % of a galaxy’s metals must be lost to the IGM to explain the observed IGM metallicity

The effect of the galactic radiation field least explored aspect of feedback: highly important for reionization but observational evidence difficult to obtain. Idea: different spectral shapes of the ionizing radiation produce different ratios among common metal ions strong CIV metal absorption systems (interior of LSS filaments, outer halos) are ionized by a stellar radiation field (T~40,000 K) (Boksenberg, Sargent & Rauch 1998,2003) matching observed relative C and O metallicities in the IGM to those of metal-poor stars ([C/O]= -0.5) requires soft (stellar) radiation field (Simcoe et al 2004)

Signatures of Bubbles and Winds in the ISM 30 Dor (LMC); Wang 1999 “spherical”, expanding shells compressed, shocked gas hot interior (10^6 K) transitory, cooling zone (OVI; 10^5 K) cool dense layer (MgII; few x 10^4 K) collisional + photoionization “spherical”, expanding shells compressed, shocked gas hot interior (10^6 K) transitory, cooling zone (OVI; 10^5 K) cool dense layer (MgII; few x 10^4 K) collisional + photoionization

Probe ISM gas with multiple lines of sight to lensed QSOs

A possible galactic HI shell MgII absorption system at z~0.56 Curious two-component structure coherent over ~1kpc : LoS intersecting two bubble walls ?

Do high z winds manage to get out of galaxies ? Two approaches: 1. look directly into galaxies and their immediate neighbourhood - learn about individual winds, connection of winds and stelpops. - learn about individual winds, connection of winds and stelpops. 2. look at random places in spaces and do a blind search for winds - learn about global statistics of winds - learn about global statistics of winds

(Pettini et al 2000) Lyman break galaxies have outflows with several 100 km/s, similar to present day superwinds Can we observe winds outside of galaxies ? A lack of neutral hydrogen within 0.5 comoving Mpc from those objects may correspond to wind-blown cavities (Adelberger et al 2003)

shock heated (collisionally ionized) gasshock heated (collisionally ionized) gas large, rapidly expanding shell structureslarge, rapidly expanding shell structures metal enriched gasmetal enriched gas 2. Search the IGM directly for use OVI ion as a tracer of galactic winds OVI survey at z ~2.5 with Keck HIRES (Simcoe et al 2002) OVI survey at z ~2.5 with Keck HIRES (Simcoe et al 2002)

Evidence for symmetric in/outflow: ( Simcoe et al 2002) ~ ¼ of strong OVI absorbers show conspicuous double component structure in HI and other ions. Shocked shell ? Bi-polar outflow ? OVI HI Ly alpha OVI

Temperatures of OVI, CIV and SiIV If line widths predominantly thermal, the median temperature of the OVI phase is whereas Simcoe et al 2002 Probably shocked gas or thermal conduction in a hot bubble

Properties of OVI systems High metallicity as opposed to average metallicity in the IGM, Sizes L ~ 60 kpc, densities (Simcoe et al 2002)

Number density and cross section from rate of incidence per unit redshift If all bright Ly break galaxies had such an OVI halo around them (with comov. density ; Adelberger & Steidel 2000): At z = 2.5 Lybreak galaxies could account for all of the observed OVI absorption in the Simcoe et al survey if they are embedded in hot bubbles out to radii ~ 40 kpc

Summary: Highly ionized (OVI) Gas (Simcoe et al 2002) Summary: Highly ionized (OVI) Gas (Simcoe et al 2002) OVI kinematically distinct from and hotter than other gas phases (CIV) OVI kinematically distinct from and hotter than other gas phases (CIV) shocked gas ? shocked gas ? peculiar double component structure relatively common in strongest systems. shells or cones ? peculiar double component structure relatively common in strongest systems. shells or cones ? sizes a few tens of kpc, overdensities around 10 – 30 (as opposed to > 100 for strong CIV/SiIV systems). sizes a few tens of kpc, overdensities around 10 – 30 (as opposed to > 100 for strong CIV/SiIV systems). external to galaxies external to galaxies Metallicity [O/H] > -1.5 higher than general IGM Metallicity [O/H] > -1.5 higher than general IGM outflow, as opposed to infall outflow, as opposed to infall cross-section consistent with R~ 40 kpc hot bubbles around Lyman break galaxies cross-section consistent with R~ 40 kpc hot bubbles around Lyman break galaxies

Kinematic effects of feedback: Bulk motion and turbulence in the IGM

Kinematics of the IGM Probe bulk motion and turbulence with multiple lines of sight: Lensed QSO IGM observer grav. lens Velocity and column density differences as a function of spatial scale, density

Becker et al 2004 Becker et al 2004 Spatial coherence and kinematics in the IGM sep ~ 0.22 kpc sep ~ 260 kpc

Expect: Large scale motion represent Hubble expansion Small scale motion are hydrodynamic disturbances (e.g., winds)

Large Scale Velocity Shear in the IGM Differences between the velocities of the same absorber in two lines of sight separated by S: On kpc scales, velocity shear consistent with zero. On kpc scales, velocity shear consistent with zero. On large scales (250 kpc), a significant velocity shear (~ 30km/s RMS) is visible. On large scales (250 kpc), a significant velocity shear (~ 30km/s RMS) is visible. Its distribution can be reproduced assuming the clouds are randomly orientated, freely expanding slabs. Its distribution can be reproduced assuming the clouds are randomly orientated, freely expanding slabs.

Is the large scale motion consistent with the Hubble flow ?

Adopting a coherence length ~500 physical kpc (e.g., D’Odorico etal 1998), expansion velocity is about 70 % of Hubble flow. expansion velocity is about 70 % of Hubble flow. Not clear whether one should expect to find clouds to follow Hubble flow exactly (column density limited sample, crude modelling, observational errors)

The Lyman alpha forest on kpc scales as seen in two Lines of sight towards RXJ (z=2.80) 2.2 kpc “0” kpc

degree of disturbances among two lines of sight tells us about filling factor of winds

upper limit on the volume filling factor of ‘winds’: Mechanical luminosity gas density e.g., winds starting at z~4 cannot fill more than 18% of the volume. (Rauch et al 2002)

General low density IGM at z~3 Large scale motions consistent with full Hubble expansionLarge scale motions consistent with full Hubble expansion Most of the intergalactic medium (by volume) is highly homogeneous on kpc scales.Most of the intergalactic medium (by volume) is highly homogeneous on kpc scales. The volume filling factor for strong winds arising later than z~4 is less than 18% (possibly much less).The volume filling factor for strong winds arising later than z~4 is less than 18% (possibly much less). Low density Lyman alpha forest probably well described by numerical simulations with finite resolution and without any feedback (but see metal absorption systems)Low density Lyman alpha forest probably well described by numerical simulations with finite resolution and without any feedback (but see metal absorption systems)

Going to higher density regions…

Spectra of UM673 A (red) and B (black) (z(QSO) = 2.72, sep. =2.24”) metals ! r = 480 pc z~z(QSO); r = “0” pc

Traces of galactic winds in higher density, metal enriched CIV gas ? Origin of velocity differences, spatial scales ? a few – 200; velocity width < 300 km/s a few – 200; velocity width < 300 km/s characteristic of the filamentary matrix in which galaxies are embedded

Measure differences between lines of sight A and B as a function of transverse separation between the LoS: Column density weighted projected velocity: transverse separation (kpc) Fractional difference in column density: Results: minimum size of CIV clouds (a few 100 pc) minimum size of CIV clouds (a few 100 pc) increasing velocity shear 10 kpc) increasing velocity shear 10 kpc)

What Does It Mean ? or are measures of the turbulence of the gas on a spatial scale r, and of the rate of energy input,. E.g., for Kolmogorov case, A crude estimate of the energy transfer rate from our data: i.e., the turbulent energy in CIV gas is much less than for an actively starforming region (e.g., factors less than for Orion).

There is a finite amount of turbulent energy in the gas. Defines a dissipation time scale (time it takes to transform the mean kinetic energy in the gas, at a rate into heat), years. The finite size of the CIV clouds defines relaxation time scale: Without further energy input, pressure and density differences are wiped out by pressure waves during a sound crossing time : years. Structure on larger scales has not been wiped out there is (at least intermittent) energy input into the gas.

Origin of the turbulence ? Gas may have been stirred by mergers/tidal interactions or winds, or it may just be circling the drain Timescales are similar to those of recurrent star formation events that have been postulated for various environments: z~1 field galaxies (Glazebrook et al 1999) the Galaxy (Rocha-Pinto et al 2000) fluctuations in SFR in nearby spirals (Tomita et al 1996; Hirashita & Kamaya 2000) g alactic nuclei (Krugel & Tutukov 1993) L yman break galaxies (Papovich, Dickinson & Ferguson 2001)

CIV absorption from the filamentary LSS structure SPH modelling of pre-enriched gas undergoing gravitational collapse reproduces all know properties of CIV systems (except clustering – box too small) Distribution of CIV line widths (thermal + turbulent) Rauch, Haehnelt & Steinmetz 1997

“structure function” of the universe Velocity-density-scale diagram

Summary: evidence for feedback in the IGM ? Cosmic web widely metal enriched down to mean densityCosmic web widely metal enriched down to mean density CIV metal absorbers ionized by local stellar radiation fieldCIV metal absorbers ionized by local stellar radiation field General low density IGM (the universe by volume) kinematically undisturbed by feedbackGeneral low density IGM (the universe by volume) kinematically undisturbed by feedback kinematic disturbances in the somewhat denser CIV gas; low level (intermittent) energy input; filamentary gas possibly stirred by galaxy motions, winds, circling the drainkinematic disturbances in the somewhat denser CIV gas; low level (intermittent) energy input; filamentary gas possibly stirred by galaxy motions, winds, circling the drain Double component structure, temperatures, expansion velocities, and the high metallicity seen in some MgII (low ionization, dense gas) and OVI (high ioniz., tenuous hot gas) point to ISM and IGM windsDouble component structure, temperatures, expansion velocities, and the high metallicity seen in some MgII (low ionization, dense gas) and OVI (high ioniz., tenuous hot gas) point to ISM and IGM winds velocities and ionization structure around high z starburst gals. consistent with superwindsvelocities and ionization structure around high z starburst gals. consistent with superwinds Inevitable that some of the “wind” phenomena described here are not due to winds but to gravitationally induced heating, motions,strippingInevitable that some of the “wind” phenomena described here are not due to winds but to gravitationally induced heating, motions,stripping To date origin and and timing of most of the metal enrichment unclear; probably early (z>5) and by dwarf galaxiesTo date origin and and timing of most of the metal enrichment unclear; probably early (z>5) and by dwarf galaxies

When does the wide spread metal enrichment happen ? E.g., Early vs. late (ongoing) enrichment Massive vs. dwarf galaxies Gravitational vs. winds ambient universe much denser at high z, ram pressure from infalling gas favors winds from dwarfs (e.g., Fujita et al 2004) ambient universe much denser at high z, ram pressure from infalling gas favors winds from dwarfs (e.g., Fujita et al 2004) mass-metallicity relation may indicate mass loss to IGM dominated by dwarf galaxies (Tremonti et al 2004) mass-metallicity relation may indicate mass loss to IGM dominated by dwarf galaxies (Tremonti et al 2004) quiescence of Lyman alpha forest, ubiquity of metals appears to favour early, widespread (= dwarf?) enrichment, ongoing locally (OVI winds, CIV turbulence) quiescence of Lyman alpha forest, ubiquity of metals appears to favour early, widespread (= dwarf?) enrichment, ongoing locally (OVI winds, CIV turbulence)

Gravitational motion (accretion,tidal,merging) winds quiescence of general IGM consistentcan’t be important CIV turbulence consistent ? OVI systems temperatures consistent OVI kinematics (double components) accretion shockwind shell High OVI metallicity stripping of ISMmetal rich winds Depletion of Ly break gals. Ionized by accretion shock, cluster radiation blown away by wind Gravitational effects vs. winds ?

Case I: possible old SN remnant at z = 3.62 Radius 13 < R < 48 pc thickness (LoS): < L< 1.6 pc Mass range 0.4 < M < 2700 Expansion velocity v > 195 km/s Number density 0.2 < n < 2 metallicity age ~ 10,000 years

Interactions between Galaxies and the IGM Galaxies accrete gas (infall velocities ~ 100 km/s) merge (approaching c.o.m. with velocities ~ 200km/s) interact tidally, lose gas by ram pressure stripping move about, stirring and heating the IGM ( T up to 10^6 K) may have strong winds (outflows w. many 100 km/s) produce ionizing radiation accrete gas (infall velocities ~ 100 km/s) merge (approaching c.o.m. with velocities ~ 200km/s) interact tidally, lose gas by ram pressure stripping move about, stirring and heating the IGM ( T up to 10^6 K) may have strong winds (outflows w. many 100 km/s) produce ionizing radiation

‘Structure function’ of the universe

Evidence for individual winds ?

General low density IGM at z~3 Large scale motions consistent with full Hubble expansionLarge scale motions consistent with full Hubble expansion Most of the intergalactic medium (by volume) is highly homogeneous on kpc scales.Most of the intergalactic medium (by volume) is highly homogeneous on kpc scales. The fraction of the Lyman alpha forest disturbed by more than 5% in optical depth is < 23% (very conservative)The fraction of the Lyman alpha forest disturbed by more than 5% in optical depth is < 23% (very conservative) The volume filling factor for strong winds arising later than z~10 is less than 20% (possibly much less).The volume filling factor for strong winds arising later than z~10 is less than 20% (possibly much less). Low density Lyman alpha forest probably well described by numerical simulations with finite resolution and without any feedback (but see metal absorption systems)Low density Lyman alpha forest probably well described by numerical simulations with finite resolution and without any feedback (but see metal absorption systems)

The Silence of the Lines: Translate column density into baryon density fluctuations, making use of tight correlation Obtain RMS scatter of the baryon overdensity: For a beam separation of 110 pc proper, and a sample of unsaturated Lyalpha forest lines with 12<logN<14.13, the RMS fluctuations in the baryon density are less than about 3 %. Similarly, RMS velocity differences !!!

What about large scale motions ? What about large scale motions ? Consistent with Hubble flow ? Consistent with Hubble flow ? Peculiar velocities ? Peculiar velocities ? Signs of feedback (winds) ? Signs of feedback (winds) ?

Define ‘disturbed fraction of the Lyalpha forest’ = fraction of the spectrum where the optical depths differ by more than a certain amount Measure Where is the width of the spectroscopic ‘footprint’ of a wind bubble intersecting a line of sight (two thermally broadened absorption lines from a crossing shell). and are the radius and expansion velocity of the shell, and is the space density of the sources of the wind events. Adopt a model for and (e.g., superbubble model of Mac Low & McCray 1988 and solve for.

upper limit on the number density of galaxies producing ‘winds’: upper limit on the volume filling factor of ‘winds’:

There is a finite amount of turbulent energy in the gas. Defines a dissipation time scale (time it takes to transform the mean kinetic energy in the gas, at a rate into heat), years. The finite size of the CIV clouds defines another time scale: Without further energy input, pressure and density differences are wiped out by pressure waves during a sound crossing time : years. Structure on larger scales has not been wiped out there is (at least intermittent) energy input into the gas.

(Pettini et al 2000) Lyman break galaxies have outflows with several 100 km/s, similar to present day superwinds Can we observe winds outside of galaxies ? A lack of neutral hydrogen within 0.5 comoving Mpc from those objects may correspond to wind-blown cavities (Adelberger et al 2003)

Low vs. high mass gals. as the origin of metals in the IGM Evidence in favor of massive galaxies: superwinds at low z blow out of galaxies (e.g., Heckman 2001), and strong winds seen in Lyman break galaxies (Pettini et al 2000) Lack of neutral hydrogen around high z starburst galaxies (Adelberger et al 2003) superwinds grafted onto massive galaxies in large scale cosmological hydro- simulations manage to get the metals out Evidence in favor of dwarf galaxies: high resolution simulations of winds: infall and high density of the IGM at high z favor dwarf galaxies outflows (e.g., Fujita et al 2004) z~0.1 mass-metallicity relation (Tremonti et al 2004): mass loss dominated by low mass galaxies. Lack of neutral hydrogen around starburst galaxies (Adelberger et al 2003) may have explanations other than winds (hot, highly ionized gas from accretion; photoionization by cluster radiation field).

(Pettini et al 2000) Spectra of massive high z starburst galaxies have outflow features similar to present day superwinds winds linked to individual galaxies A lack of neutral hydrogen within 0.5 comoving Mpc from those objects may correspond to wind-blown cavities (Adelberger et al 2003) But: ambient universe much denser at high z, ram pressure from infalling gas favors winds from dwarfs (Fujita et al 2004) ambient universe much denser at high z, ram pressure from infalling gas favors winds from dwarfs (Fujita et al 2004) mass-metallicity relation indicates mass loss to IGM dominated by dwarf galaxies (Tremonti et al 2004) mass-metallicity relation indicates mass loss to IGM dominated by dwarf galaxies (Tremonti et al 2004) But: May have alternative explanations: merger-heated halo, cluster radiation field

Anecdotal evidence for the existence of ISM shells ok, but objects are much smaller and weaker than required for wind bubbles that leave the galaxy.

Too quiescent to be directly related to starformationToo quiescent to be directly related to starformation residual turbulence and finite cloud sizes suggest ongoing (at z~3) low level, energy input on timescales ~ Mio years. Time scales are similar to those involved in recurrent starformation events. Winds or galaxy encounters (accretion, mergers, stripping) may play a role.Time scales are similar to those involved in recurrent starformation events. Winds or galaxy encounters (accretion, mergers, stripping) may play a role. CIV Gas: “structure function” of the universe