104 lines
2.4 KiB
Typst
104 lines
2.4 KiB
Typst
#import "globals.typ": *
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= Simulating the Epoch of Reionization
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// == The Epoch of Reionization
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// - Marks the universe’s last major phase transition: from neutral to ionized hydrogen.
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// - Shapes the large-scale structure of the intergalactic medium (IGM).
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// - Is strongly linked to the formation and growth of the first galaxies and black holes.
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// - Sets the stage for many observables:
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// - CMB secondary anisotropies
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// - 21-cm signal
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// - high-z galaxy surveys.
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// // reformulate
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== The 21-cm signal
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The _brigthtness temperature_ describes the intensity of the 21-cm line
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#v(1em)
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#grid(columns: 2, align: center, column-gutter: 1em)[
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#image("assets/cmb_and_dtb.jpeg", height: 1fr, fit: "contain") #text(size: 0.8em)[from @cmb_spectrum]
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][
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#pause
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#set text(size: 0.8em)
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remove contribution from the BB spectrum
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_differential brightness temperature_
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$==>$ the actual reionization signal
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#image("assets/brighness_temperature.png", fit: "contain")
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from @Schaeffer_2023
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]
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#pagebreak()
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== Expression the 21-cm signal @Pritchard2012 @Furlanetto_2006
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#align(center)[
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#image("assets/evolution_of_dtb.png", height: 70%, fit: "contain")
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// #text(size: 0.8em)[from @Pritchard2012]
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]
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#pause
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$
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d T_"b" (bold(x), z) tilde.eq T_0 (z) dot
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#pin(1) x_"HI" (bold(x), z) #pin(2) dot
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(1 + delta_b (bold(x), z)) dot
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(x_alpha (bold(x), z)) / (#pin(3) 1 + x_alpha (bold(x), z) #pin(4) ) dot
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((1 - T_"CMB" (z)) / (#pin(5) T_"gas" (bold(x), z) #pin(6)))
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$ <eq:dTb>
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== The current state of simulations
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#layouts.contained(
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[
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*Traditional approaches*
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// From first principles
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$->$ need to cover large dynamic range
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// small scales to resolve sources + sinks + feedback
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// large scales to capture statistics
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$->$ hydrodynamics & radiative transfer
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$->$ hard to scale
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$=>$ no reproducibility
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#pause
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],
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[
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#pad(1em)[
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#align(left)[
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#text(weight: "bold")[Semi-numerical approaches]
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such as #beorn @Schaeffer_2023, `21cmFAST` @21cmfast
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// IF ASKED: difference with `21cmFAST`:
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// based on excursion formalistm -> only valid >= 1Mpc, which is ideal for large volumes + statistics => 21-cm forecasts
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$->$ approximative treatment
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$->$ prediction of global signals
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// and statisticical properties
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$->$ scalable + efficient
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$=>$ reproducible and flexible
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// interesting to build emulators for instance
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]
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]
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]
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)
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