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Understanding Argon Deficiency in DLA Systems: Importance, Trends, and Interpretations

Investigating the deficiency of Argon in DLAs and exploring the possible reasons such as nucleosynthesis and photoionization effects. Examining trends with metallicity and ionization conditions. Discusses implications for high-redshift HeII reionization stages.

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Understanding Argon Deficiency in DLA Systems: Importance, Trends, and Interpretations

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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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