109 lines
2.5 KiB
Typst
109 lines
2.5 KiB
Typst
#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, column-gutter: 1em)[
|
||
#image("assets/cmb_and_dtb.jpeg", height: 1fr, fit: "contain") #text(size: 0.8em)[from @cmb_spectrum]
|
||
][
|
||
#pause
|
||
#set text(size: 0.8em)
|
||
remove contribution from the BB spectrum:
|
||
|
||
_differential brightness temperature_
|
||
|
||
$==>$ the actual 21-cm signal
|
||
|
||
#image("assets/brighness_temperature.png", fit: "contain")
|
||
from @Schaeffer_2023
|
||
]
|
||
|
||
#pagebreak()
|
||
|
||
|
||
|
||
#align(center)[
|
||
#image("assets/evolution_of_dtb.png", height: 85%, fit: "contain")
|
||
#text(size: 0.8em)[from @Pritchard2012]
|
||
]
|
||
|
||
// COMMENTS:
|
||
|
||
|
||
|
||
== 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*
|
||
// From first principles
|
||
- need to cover large dynamic range
|
||
// small scales to resolve sources + sinks + feedback
|
||
// large scales to capture statistics
|
||
- hydrodynamics & radiative transfer
|
||
- hard to scale
|
||
|
||
$=>$ no reproducibility
|
||
#pause
|
||
],
|
||
[
|
||
#pad(1em)[
|
||
#align(left)[
|
||
#text(weight: "bold")[semi-numerical approaches]
|
||
|
||
such as #beorn @Schaeffer_2023, `21cmFAST` @21cmfast
|
||
|
||
// IF ASKED: difference with `21cmFAST`:
|
||
// based on excursion formalistm -> only valid >= 1Mpc, which is ideal for large volumes + statistics => 21-cm forecasts
|
||
|
||
$->$ approximative treatment
|
||
|
||
$->$ link
|
||
|
||
$->$ scalable + efficient
|
||
|
||
$=>$ reproducible and flexible
|
||
// interesting to build emulators for instance
|
||
]
|
||
|
||
]
|
||
]
|
||
)
|
||
|