Intergalactic metals at the conclusion of reionization

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1 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

2 Cosmological Mass Density?

3 Cosmological Mass Density Drop x 3 in 160 Myrs

4 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.

5 Detecting the IGM as z 6 The landscape changes Womble et al White et al. 2003

6 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)

7 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).

8 Literature Ryan Weber et al Becker et al D Odorico et al Simcoe et al. 2011

9 Cosmological Mass Density? Ryan Weber et al Becker et al Simcoe et al D Odorico et al } 14 QSO sight lines 111 CIV doublets ΔX=71

10 Cosmological Mass Density Ω CIV = H 0 m CIV cρ crit N CIV ΔX = Drop x 3 in 160 Myrs

11 Cosmological Mass Density

12 Cosmological Mass density Numerical models Oppenheimer & Davé (2008) ERW (model with constant δ,z,t) SimulaZon results Cen & Chisari (2011) Intergalac*c metals at z~6 Emma Ryan Weber (Swinburne)

13 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 Intergalac*c metals at z~6 Emma Ryan Weber (Swinburne)

14 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)

15 IGM metallicity at z=5.6 Z IGM = Ω CII + Ω CIV Ω b. 1 A c. = 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)

16 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 = 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)

17 Comparison with galaxy Luminosity Function Can stars reionize the Universe? Robertson et al 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)

18 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)

19 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) = 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)

20 .

21 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)