Intergalactic metals at the conclusion of reionization Emma Ryan Weber (Swinburne) Max Pe'ni George Becker Berkeley Zych Piero Madau Bram Venemans Gonzalo Diaz Jeff Cooke
Cosmological Mass Density?
Cosmological Mass Density Drop x 3 in 160 Myrs
Are there enough ionizing photons inferred from IGM metals at z>5.6 to reionize cosmic hydrogen? Too low by a factor of 3 ΩCIV+ΩCII (z=5.6) ZIGM =3.5x10 4 Z whereas ZIGM ~ 1x10 3 Z # is required.
Detecting the IGM as z 6 The landscape changes Womble et al. 1996 White et al. 2003
ISAAC/X shooter/vlt & NIRSPEC/Keck significant challenges: OH skylines, atmospheric absorption 5.5<z(CIV)<7.5 nm Demonstrated that medium resoluzon quasar absorpzon line spectroscopic is viable in the near IR. Ryan Weber et al. (2006), Simcoe (2006)
Search for CIV absorbers at 4.3<z<6.3 Currently ~ 30 quasars with z em >5.7 bright enough for this work (SDSS, UKIDSS, CFHQS).
Literature Ryan Weber et al. 2009 Becker et al. 2009 D Odorico et al. 2013 Simcoe et al. 2011
Cosmological Mass Density? Ryan Weber et al. 2009 Becker et al. 2009 Simcoe et al. 2011 D Odorico et al. 2013 } 14 QSO sight lines 111 CIV doublets ΔX=71
Cosmological Mass Density Ω CIV = H 0 m CIV cρ crit N CIV ΔX = 5.0 10 9 Drop x 3 in 160 Myrs
Cosmological Mass Density
Cosmological Mass density Numerical models Oppenheimer & Davé (2008) ERW+ 2013 (model with constant δ,z,t) SimulaZon results Cen & Chisari (2011) Intergalac*c metals at z~6 Emma Ryan Weber (Swinburne)
Where do CIV absorbers lie? At z~2.3 Lyman break galaxies can account for ~50% of CIV absorbers with log(n(civ)/cm)>13.6 within a impact parameter of 90 kpc (Steidel et al. 2010). However, D Odorico et al. (2013) find that the N(CII)/N(CIV) razo of high column density systems at z=5.7 are best represented by CLOUDY models of gas with over densizes of 10 rather than 100. D Odorico et al. 2013 Intergalac*c metals at z~6 Emma Ryan Weber (Swinburne)
Association of CIV absorbers with galaxies and large scale structure Poster by Gonzalo Diaz: CIV absorbers; LBGs and LAEs at z=5.7 Finds region around strong CIV absorbers UNDERDENSE in LBGs, but OVERDENSE in LAEs. See also Cooke, Omori & Ryan Weber (2013) on the anzcorrelazon of z~3 LBGs detected with emission and absorpzon features. Intergalac*c metals at z~6 Emma Ryan Weber (Swinburne)
IGM metallicity at z=5.6 Z IGM = Ω CII + Ω CIV Ω b. 1 A c. = 3.5 10 4 Z A c = fraczon of metals in carbon 1 f (x CII ) + f (x CIV ) Ω CII =8x10 9 (z=5.3 to 6.2 Becker et al. 2006) f(x CII )+f(x CIV )~0.4 (Oppenheimer & Schaye 2013) Can use Z IGM to es*mate past total sum of stellar light Key point: same massive stars are responsible for metals and ionizing flux. Madau & Shull (1996) showed that changing Salpeter IMF α=2 to 3 results in a 10% change in Lyman ConZnuum (LyC) photons Intergalac*c metals at z~6 Emma Ryan Weber (Swinburne)
Are there enough ionizing photons inferred from IGM metals at z>5.6 to reionize cosmic hydrogen? E Z = ηm p c 2 Z MeV η = 0.014 for stars with Z=1/50 Z Average energy of 21 ev per LyC photon (Schaerer, 2002). RelaZonship is insensizve to the inizal mass funczon (IMF). Z IGM = 3.5x10 4 Z 2.8 LyC photons per baryon emiued prior to z=5.6. Two to three photons per baryon are required to guard against recombinazons in a clumpy IGM at z=6 (Bolton & Haehnelt 2007; McQuinn et al. 2011; Finlator et al. 2012) However, not all ionizing photons escape from galaxies (fesc ~0.2, see also talk by Jeff Cooke), and 75% metals are expected to reach the IGM (Dave & Oppenheimer 2006). Measured carbon density is insufficient reionize cosmic hydrogen by a factor of ~3. Intergalac*c metals at z~6 Emma Ryan Weber (Swinburne)
Comparison with galaxy Luminosity Function Can stars reionize the Universe? Robertson et al. 2013 Synthesis of UDF12 PopulaZon of star forming galaxies at z=7 9 must extend to M UV fainter than 13 to fully reionize the Universe by z=6. Intergalac*c metals at z~6 Emma Ryan Weber (Swinburne)
Future Prospects 14 QSO sight lines, 111 CIV doublets, ΔX=71 Further 8 unique QSO sight lines: 2 X shooter, 6 NIRSPEC. Provide addizonal ΔX 51. Further progress will be made when we can get a beuer handle on the IGM ionizazon state by measuring CII/CIV and/ or SiII/SiIII/SiIV in the same systems. Intergalac*c metals at z~6 Emma Ryan Weber (Swinburne)
Summary Ω CIV declines by a factor of 3 between z=5.0 and z=5.6. Ω CIV (z = 5.6) = 5.0(±0.2) 10 9 Z IGM (z = 5.6) = 3.5 10 4 Z Z IGM (required) ~ 10 3 Z The carbon density falls short of that required for reioniza*on of cosmic hydrogen by a factor 3, but the accounzng exercise involves some best eszmate factors from simulazons: 0.75 (metals escape), 2 (clumping), 2.5 (Ωtot/Ω(CII+CIV)) and 5 (fesc). Reioniza*on of cosmic hydrogen was likely to be `photon staved. Strong CIV absorbers at z=5.7 are not associated with the highest density peaks of LBGs, but with instead with overdense regions of LAEs Intergalac*c metals at z~6 Emma Ryan Weber (Swinburne)
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Missing carbon Lack of carbon expelled from early stars? Unlikely. Heger & Woosley 2002: Pop III yields ObservaZons of low Z halo stars (Akerman et al. 2004) and DLAs (Pe'ni et al. 2008) Intergalac*c metals at z~6 Emma Ryan Weber (Swinburne)