LAEs on Cosmological Scales

class: center, middle

.title[Lyman-alpha Emitters on Cosmological Scales]

.subtitle[Radiative Transfer Characteristics in Mock Galaxy Surveys and Intensity Mapping]

.author[Chris Byrohl]

.institution[University of Goettingen, Germany]

.date[October 04, 2017]

---
##  Outline

1. The Basics
 
The Lyman-alpha Line and its Radiative Transfer Properties
 
Methodology

2. Results
 
Spectra and radial profiles of LAEs
 
Redshift Surveys
 
Intensity Mapping

---
## The Lyman Alpha Line

* Resonant frequency for the `\(n=2\rightarrow 1\)` transition of hydrogen.

* Large cross-section:

\(\sigma_{\alpha,0}\sim 6\cdot 10^{-14} (T/10^4)^{-1/2} cm^{2}\)

<figure>
 <img style="width:65%;margin:0px auto;display:block" src="../figures_new/profile_voigt.png">
 <figcaption>Voigt Line Profile.</figcaption>
</figure>

<!---
## A Recipe for Radiative Transfer

* `\(I_\nu\)` = Emission - Absorption + Redistribution

* Redistribution complicated by integration over angle and frequency distribution at other frequencies.

<figure style="width:55%;float: left;display:block;"><img style="width:100%;" src="../figures_new/profile_voigt.png"</img>
	 <figcaption>Voigt Line Profile</figcaption>
 </figure>

\(\langle \Delta x|x'\rangle = -\frac{1}{x'}\) 
 \(\sqrt{\langle\Delta x^2|x'\rangle} = 1\)

-->
---
## Radiative Transfer Toy Models

---
## Radiative Transfer Toy Models (2)

---
## Lyman Alpha Observations

<figure style="width:90%;float:center;"><img style="width:100%;" src="../figures_new/hayes15_obsLAEs.png"</img>
 <figcaption>Example of observed LAEs as shown in Hayes 2015.</figcaption>
 </figure>

---
##  Methodology

<figure>
 <img style="width:100%;margin:0px auto;display:block" src="../figures_new/methodology.svg">
 <figcaption>Schematic Methodology.</figcaption>
</figure>

---
## Results

---
## Results - Individual LAEs

---
## Results - Individual LAEs

---
## Results - Statistical Analysis

---
## Results - Statistical Analysis

---
## Results - Statistical Analysis: Emitter Detection

<figure>
 <img style="width:60%;margin:0px auto;display:block;" src="../figures_new/detection_ZZ.png"</img>
 <figcaption>Source detection method.<figcaption>
 </figure>

---

##  Statistical Analysis - Galaxy Clustering

<figure style="width:35%;float: right;display:block;"><img style="width:100%;" src="../figures/ZZ_anisotropy.png"></img>
	 <figcaption>(<a href="https://arxiv.org/pdf/1003.4990v3.pdf">Zheng et al., 2011</a>) </figcaption>
 </figure> 
 
 
 
 
 
 
 → (<a href="https://arxiv.org/pdf/1003.4990v3.pdf">Zheng et al., 2011</a>)
	 find 2PCF to be deformed by a Radiative Transfer Effect.

<figure style="width:35%;float: left;display:block;"><img style="width:100%;" src="../figures/croft_anisotropy.png"></img>
 <figcaption>(<a href="https://arxiv.org/abs/1504.04088">Croft et al., 2016</a>)
 </figure> 
 
 
 
 → (<a href="https://arxiv.org/abs/1504.04088">Croft et al., 2016</a>)
compute similar elongation from observations, explained with (<a href="https://arxiv.org/pdf/1003.4990v3.pdf">Zheng et al., 2011</a>).

→ Problem for HETDEX?

---
## Statistical Analysis - Galaxy Clustering: Radiative Transfer Distortion?
<figure>
 <img style="width:90%;margin:0px auto;display:block" src="../figures/rteffect.png">
 <figcaption>Schematic of the RT Effect.</figcaption>
</figure>

---
## Statistical Analysis - Galaxy Clustering: Radiative Transfer Distortion?

---
## Statistical Analysis - Galaxy Clustering: Radiative Transfer Distortion?
 <figure style="width:100%;float:center;"><img style="width:75%;" src="../figures_new/corr_srs_ZZ_velocitygrad.png"</img>
 </figure>

---
## Statistical Analysis - Galaxy Clustering: Radiative Transfer Distortion?
 <figure style="width:100%;float:center;"><img style="width:85%;" src="../figures_new/RSdistort_bestworst.png"</img>
 </figure>

---
## Statistical Analysis - Galaxy Clustering: Radiative Transfer Distortion?

---
## Statistical Analysis - Galaxy Clustering: Radiative Transfer Distortion?

---
## Statistical Analysis - Galaxy Clustering: Radiative Transfer Distortion?

--
 
 
 → Prior findings likely artificial due to resolution (and emitter model).
 
 → Artificial RT effect depends on the frequency distribution.
 
 → Based on our findings, no such effect expected in Lyman alpha surveys, particularly at low redshift.

---
## Results - Intensity Mapping

---
## Results - Intensity Mapping

→ Imprints of radiative transfer on Mpc scales!
 
 → Increasing influence with redshift.

---
## Results - Intensity Mapping: Redshift Space

---
## Results - Intensity Mapping: Redshift Space

---
##  Summary

__**1. Individual LAEs**__
* Can trace the neutral hydrogen density/velocity structure.

* Most of the emission contributes to a **diffuse background**.

* **Double peak profile** cannot be observed at high redshifts.

---
##  Summary

__**2. Galaxy Clustering**__
* If there is a correlation of observed fraction of photons and the **velocity gradient**, decreased clustering along the line of sight is possible.

* This **Radiative Transfer Effect** has an artificial cause due to lacking hydrodynamic resolution of prior studies.

* Artificial effect can be attributed to change in spectrum.

---
## Summary

__**3. Intensity Mapping**__
* Radiative transfer impacts power spectrum even on Megaparsec scales.

* Non-trivial correlation signal with neutral hydrogen can be used to constrain IGM properties (e.g. use 21cm line).

* Finger of Gods-like redshift space distortion from radiative transfer up to large scales.