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Insights into Emission from Damped Lyman-Alpha Systems

Explore the significance of Damped Lyman-Alpha Systems (DLAs) as neutral gas reservoirs for star formation and their dominance in the universe's gas content at various redshifts. Learn about DLAs' cooling rates, nucleosynthesis, and the impact of FUV heating in galaxies. Discover more through emission rates and predicted mass ranges in CDM models.

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Insights into Emission from Damped Lyman-Alpha Systems

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  1. [C II] 158 mm Emission from Damped Lya Systems Art Wolfe and Ken Nagamine UCSD

  2. DLAS are • Definition of Damped Lya System (DLA): N(HI) > 2*1020 cm-2 • Distinguishing characteristic of DLAs : Gas is Neutral

  3. DLAS are • Definition: N(HI) > 2*1020 cm-2 • Distinguishing characteristic of DLAs : Gas is Neutral Stars form out of cold gas

  4. Relevance of DLAs for Star Formation • DLAs Dominate the Neutral Gas Content of the Universe at z=[0,5] • Gas Content of DLAs at z=[3,4] Accounts for current visible Mass • DLAs Serve as Important Neutral Gas Reservoirs for Star Formation

  5. DLAs Dominate the Neutral Gas Content of the Universe at z=[0,5] • Gas Content of DLAs at z=[3,4] Accounts for current visible Mass • DLAs Serve as Important Neutral Gas Reservoirs for Star Formation Mass per unit Comoving Volume versus redshift

  6. DLAs Dominate the Neutral Gas Content of the Universe at z=[0,5] • Gas Content of DLAs at z=[3,4] Accounts for current visible Mass • DLAs Serve as Important Neutral Gas Reservoirs for Star Formation Current Visible Matter Neutral Gas at High z

  7. HIRES Metal-line Velocity Profiles in DLAs • High-resolution spectroscopy on very large telescopes can yield quantitative information about DLAs: • Cooling Rates • Star formation rates. Nucleosynthesis Chemistry Thermal Pressure Nucleosynthesis Dust & Nucleosynthesis Kinematics SFRs Nucleosynthesis

  8. Obtaining Cooling Rates from CII* Absorption • [C II] 158 micron transition dominates cooling of neutral gas in Galaxy ISM • Spontaneous emission rate per atom lc=nL[CII] obtained from strength of 1335.7 absorption and Lyman alpha absorption • Thermal equilibrium condition lc= Gpe gives heating rate per atom

  9. [C II] 158 micron Emission rates vs N(H I) • Median lc=10-26.6 ergs s-1 H-1 for positive Detections • Upper limits tend to have low N(H I) • DLA lc values about 30 times lower than for Galaxy: explained by lower dust content and similar SFRs per unit area

  10. Effect of Adding Local FUV Heating

  11. An LBG Galaxy Associated with a DLA (Moller etal ‘02) [O III] Emission Lya Emission 8.4 kpc CII* Absorption

  12. [C II] contours superposed on 6.75 mm Image

  13. [C II] Flux Densities Predicted for DLAs

  14. Predicted Sn0 for DLA 2206-19A • 3s Alma limit for 20 hr integration time • 90 % Mass range predicted for CDM Models of DLAs • MH I =mDM

  15. Tentative lc versus Dv relation • DLA2206-19A • CDM Models predict Dv = 0.6vc • M=vc3/10GH(z)

  16. DLA2206-19A • Sn0impliedfor Mass predicted by lc versus Dv relation

  17. 608 MHz VLBI Map of PKS 0458-02 17 kpc

  18. Single-Dish versus VLBI 21 cm Absorption profiles for DLA 0458-02 at z=2.0394

  19. Alma Sensitivity for Detection of C II Emission • Lower Limit for DLA0458-02 for MH I=1010 Msun

  20. Predicted Sn0 for full Sample • “Redshift Desert’’ • CNM confirmed by absence of Si II* 1264 absorption

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