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On the deficiency of Argon in DLA systems

Tayyaba Zafar (AAO) ( tzafar@aao.gov.au ) Giovanni Vladilo, Celine Péroux, Paolo Molaro, Miriam Centurion, & Valentina D ’ Odorico. On the deficiency of Argon in DLA systems. EWASS-2017 SS14 28 June 2017. Importance of Argon. Argon is sensitive to ionization conditions

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On the deficiency of Argon in DLA systems

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  1. Tayyaba Zafar(AAO) (tzafar@aao.gov.au) Giovanni Vladilo, Celine Péroux, Paolo Molaro, Miriam Centurion, & Valentina D’Odorico On the deficiency of Argon in DLA systems EWASS-2017 SS14 28 June 2017

  2. Importance of Argon • Argon is sensitive to ionization conditions • Photoionization rate of Argon is 1 order of magnitude higher than HI • Hard photons can leak through the HI layers and ionize Ar • During the epoch of HeII reionization IGM become transparent to photons with hν > 54.4eV • ArI (λλ1048,1066) is challenging to detect in the Lyα forest • Search for ArI in 140 DLAs at z>1.7 from the EUADP sample • Profiles of ArI fitted together with SiII, SII, and FeII lines EWASS-2017 SS14 28 June 2017

  3. ArI Sample EUADP data + literature sample provided 19 measurements + 15 limits Bold are Proximate DLAs with zQSO ΔV<3000 kms-1 EWASS-2017 SS14 28 June 2017

  4. EUADP ArI Examples QSO J1113-1533 at z=3.27 QSO B2342+3417 at z=2.9 EWASS-2017 SS14 28 June 2017

  5. Deficiency of Argon in DLAs <[Ar/H]> = −1.76±0.36 Lower abundance compared to the typical DLA metallicity We used S and Si as references <[Ar/S]> = −0.61±0.21 <[Ar/Si]> = −0.66±0.25 We investigate trends between zabs, NHI and metallicity and [S/H] is used as an indicator of dust free metallicity EWASS-2017 SS14 28 June 2017

  6. Tentative trend of [Ar/α] with zabs EWASS-2017 SS14 28 June 2017

  7. Weak trend of [Ar/α] with NHI EWASS-2017 SS14 28 June 2017

  8. Tentative trend of [Ar/α] with [S/H] EWASS-2017 SS14 28 June 2017

  9. Reasons for Argon Deficiency Dust Depletion? Nucleosynthesis effects Photoionization effects? EWASS-2017 SS14 28 June 2017

  10. Ar Incorporation in Dust EWASS-2017 SS12 28 June 2017

  11. QSO-DLA dust analysis EWASS-2017 SS14 28 June 2017

  12. Nucleosynthesis Effects? Izotov & Thuan 1999 EWASS-2017 SS12 28 June 2017

  13. Nucleosynthesis Effects? EWASS-2017 SS12 28 June 2017

  14. Photoionization Effects? Jenkins et al. 2013 EWASS-2017 SS12 28 June 2017

  15. Photoionization Effects? Galaxies Contribution QSO Contribution Haardt & Madau 2012 EWASS-2017 SS14 28 June 2017

  16. Photoionization Effects? Dotted line: Soft radiation field Dashed line: Hard radiation field If Argon deficiency is due to ionization then we expect to see more deficiency for proximate DLAs EWASS-2017 SS14 28 June 2017

  17. SFR Role Mannucci et al. 2010 EWASS-2017 SS14 28 June 2017

  18. SFR role SFR  Δ[M/H] in Δt ≤1Gyr SFR  Transparency to+ emission of hard photons EWASS-2017 SS14 28 June 2017

  19. Alternative Interpretation High [M/H]  low NHI  low self shielding  high Ar ionization EWASS-2017 SS14 28 June 2017

  20. HeII reionization at z>3 Evidence of Ar deficiency is present but a gap in data at high redshift to infer HeII ionization stages EWASS-2017 SS14 28 June 2017

  21. Refresher!! • Underabundance of Argon is seen in DLAs • Analysis suggests that deficiency is due to ionization effects • This is consistent with the scenario of DLA ionization by the quasar photons • ArI appeared to me ionized at z>3 suggesting that photons with hν > 54.4eV leak through the HI layers after the HeII reionization • A large high redshift Argon sample is required to track the stages of HeII reionization EWASS-2017 SS14 28 June 2017

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