Quasar Absorption Lines
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Transcript of Quasar Absorption Lines
Quasar Absorption Lines
Tracing Cosmic Structure Growth & Galaxy EvolutionOver Cosmic Time
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Motivations and Astrophysical ContextMg II arises in environments ranging over five decades of N(HI)
• DLAs: N(HI)>2x1020 cm-2
• LLSs: N(HI)>2x1017 cm-2
• sub-LLSs: N(HI)<6x1016 cm-2
Statistical Cross-Sections, n
Giant molecular clouds?; 0.1 L* and LSB galaxies with wide range of morphologies; intergalactic clumps; n~15 kpc; black-bottom absorption with v~200 km s-1; average C IV absorption(eg. Le Brun et al 1997; Rao & Turnshek 2000; Bouche’ etal 2000; cwc etal (II) 2000)
“Normal” HSB galaxies with >0.1 L*; n~40 kpc;complex kinematics with “high velocity” componentswith v~100-400 km s-1; range of C IV absorption(eg. Steidel et al 1994; cwc etal 1996; cwc 1997; cwc & Vogt 2000) assuming *=0.03 h3 Mpc-3
“forest clouds”? LSB galaxies?; dwarf galaxies?; few associated with HSB galaxies; mostly single unresolved clouds; n~70 kpc; sizes ~10 pc to 1 kpc; Z>0.1 solar; [/Fe]~0 to +0.5; Cf~0.15; range of C IV absorption(eg. cwc & Le Brun 1998; cwc etal ApJS 1999 ; Rigby etal 2001)
Sub-LLS
Mg II selects a wide range of astrophysical sites, which can be traced from redshift 0 to 5
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What the sensitivity and resolution buy…
Steidel & Sargent (1992)
cwc (1997); cwc & Charlton (1999)
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cwc & Charlton 1999
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Chris Churchill (PSU) 12cwc 2001
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Statistically, Profiles are Consistent with …
(Charlton & cwc 1998)Monte-Carlo Models of Absorbing Galaxies
What is probability distribution for such models?Assume ~r-2 probability distribution of clouds in disk and in haloAssume Vrot=Vinfall kinematics of clouds in disk and in halo
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Voigt Profiles
Assume minimum number of components that are statistically significant (MINFIT). Parameterization does not account for asymmetric line-of-sight streaming motion.
cwc (1997); cwc, Vogt, & Charlton, ApJ, (2001)
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“Weak Systems”
• Single Clouds, Wr(MgII)<0.3 , isolated in redshift
• Unresolved line widths at 6 km s-1
• Power law equivalent width distribution down to Wr(MgII)=0.02
cwc etal, ApJS (1999)Steidel & Sargent (1992)
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