#import "globals.typ": *


= Simulating the Epoch of Reionization
== The Epoch of Reionization
- Marks the universe’s last major phase transition: from neutral to ionized hydrogen.

- Shapes the large-scale structure of the intergalactic medium (IGM).

- Is strongly linked to the formation and growth of the first galaxies and black holes.

- Sets the stage for many observables: CMB secondary anisotropies, 21-cm signal, high-z galaxy surveys.
// reformulate


== The 21-cm signal


The brigthtness temperature describes the difference between the CMB temperature and the spin temperature of neutral hydrogen

#v(1em)

#grid(columns: 2, align: center)[
  #image("assets/cmb_black_body_spectrum.svg", height: 1fr, fit: "contain")   #text(size: 0.8em)[from @cmb_spectrum]
][
  #pause
  Removing the contribution from the black body spectrum of the CMB yields the explicit 21-cm signal:
  #image("assets/cmb_black_body_spectrum.svg", height: 1fr, fit: "contain")
]

#pagebreak()



#align(center)[
  #image("assets/evolution_of_dtb.png", height: 85%, fit: "contain")
  #text(size: 0.8em)[from @Pritchard2012]
]


== Expression the 21-cm signal
Expressing the _differential brightness temperature_ (e.g @Pritchard2012):

$
  d T_"b" (bold(x), z) tilde.eq T_0 (z) dot
  #pin(1) x_"HI" (bold(x), z) #pin(2) dot
  (1 + delta_b (bold(x), z)) dot
  (x_alpha (bold(x), z)) / (#pin(3)  1 + x_alpha (bold(x), z) #pin(4) ) dot
  ((1 - T_"CMB" (z)) / (#pin(5) T_"gas" (bold(x), z) #pin(6)))
$ <eq:dTb>

// Explanation
- further modulation by _RSD_


== The current state of simulations


#layouts.contained(
  [
    *Traditional approaches*

    // keypoints that describe heavy hydro + radiative transfer simulations
    - require hydrodynamics
    - require radiative transfer
    - scale poorly

    $=>$ no reproducibility
    #pause
  ],
  [
    #text(weight: "bold")[semi-numerical approaches]

    such as #beorn @Schaeffer_2023, `21cmFAST` [CITATION]
    - approximative treatment
    - link
    - scalable + efficient

    $=>$ reproducible and flexible
  ]
)


// #layouts.two-boxes(
//   [
//     #text(weight: "bold")[Traditional approaches]

//     // keypoints that describe heavy hydro + radiative transfer simulations
//     - require hydrodynamics
//     - require radiative transfer
//     - scale poorly

//     $=>$ no reproducibility
//     #pause
//   ],
//   [
//     *semi-numerical approaches*

//     such as #beorn @Schaeffer_2023, `21cmFAST` [CITATION]
//     - approximative treatment
//     - link
//     - scalable + efficient

//     $=>$ reproducible and flexible


//   ]
// )

#pagebreak()

== Matrix

#layouts.matrix((
  brand.wordmark,
  brand.wordmark,
  brand.wordmark,
  brand.wordmark,
  brand.wordmark,
  brand.wordmark
))

== Contained
#layouts.contained(
  columns(2, [
    - #lorem(10)
    - #lorem(15)
    - #lorem(25)
  ]),
  brand.wordmark
)



== Four columns

#layouts.four-columns(
  [
    #text(weight: "bold", brand.wordmark)
    #v(1em)
    #text(size: 10.5pt)[#lorem(60)]
  ],
  [
    #text(weight: "bold", brand.wordmark)
    #v(1em)
    #text(size: 10.5pt)[#lorem(45)]
  ],
  [
    #text(weight: "bold", brand.wordmark)
    #v(1em)
    #text(size: 10.5pt)[#lorem(75)]
  ],
  [
    #text(weight: "bold", brand.wordmark)
    #v(1em)
    #text(size: 10.5pt)[#lorem(50)]
  ]
)



== Two columns

#layouts.contained(
  columns(2, [
    - #lorem(10)
    - #lorem(15)
    - #lorem(25)
  ]),
  brand.wordmark
)
