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courses:ast403:absorption-systems [2026/03/23 10:27] – [Summary of Absorption Systems] shuvocourses:ast403:absorption-systems [2026/03/26 07:03] (current) – [Infographics on Absorption Systems] shuvo
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-[{{ :courses:ast403:lymanforest.jpg?600 | Fig 2: Lyman alpha forest.}}]+[{{ :courses:ast403:lymanforest.png?600 | Fig 2: Lyman-alpha forest.}}] 
 + 
 +Here is a video of how this is generated: [[https://youtu.be/6Bn7Ka0Tjjw?si=6O0a9UhoEDe6JY4x]] 
 ===== Damped Lyman-$\alpha$ Systems (DLAs)===== ===== Damped Lyman-$\alpha$ Systems (DLAs)=====
  
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 **Enrichment:** DLAs show a gradual increase in metal abundance over cosmic time, though they typically remain metal-poor ($\sim 0.1 Z_\odot$). **Enrichment:** DLAs show a gradual increase in metal abundance over cosmic time, though they typically remain metal-poor ($\sim 0.1 Z_\odot$).
  
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 +[{{ :courses:ast403:lymanasb.jpeg?600 | Fig 3: Spectrum foa quasar at z=1.34 showing various Lyman absorptions.}}]
 ===== Lyman-Limit Systems ===== ===== Lyman-Limit Systems =====
 These systems have column densities of $N(HI) \gtrsim 2 \times 10^{17} \text{ cm}^{-2}$. \\ These systems have column densities of $N(HI) \gtrsim 2 \times 10^{17} \text{ cm}^{-2}$. \\
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-[{{ :courses:ast403:lymanasb.png?600 | Fig 3: Various absorption systems.}}] +[{{ :courses:ast403:lymanasb.png?600 | Fig 4: Various absorption systems. See [[https://arxiv.org/abs/1510.03368]] for details.}}]
-===== Broad Absorption Line (BAL) Systems ===== +
-Found in about 15% of quasars, these are not caused by the IGM but by material in the active galactic nucleus (AGN) itself.\\ +
-**Spectral Signature:** They appear as broad troughs with widths indicating gas moving toward the observer at relativistic speeds (up to $0.1c$).\\ +
-**Origin:** This is interpreted as a superwind or outflow of gas being violently ejected from the vicinity of the central supermassive black hole.+
  
 ===== The Gunn-Peterson Trough ===== ===== The Gunn-Peterson Trough =====
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-[{{ :courses:ast403:gpt.jpg?600 | Fig 3: Gunn-Peterson trough.}}]+[{{ :courses:ast403:gp_trough.jpg?600 | Fig 5: Gunn-Peterson trough.}}] 
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 ===== Infographics on Absorption Systems ===== ===== Infographics on Absorption Systems =====
  
-[{{ :courses:ast403:absorption_systems.png?800 | Fig 4: IGM absorption systems explained.}}]+[{{ :courses:ast403:absorption_systems.png?800 | Fig 6: IGM absorption systems explained.}}]
courses/ast403/absorption-systems.1774283260.txt.gz · Last modified: by shuvo
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