# The Lyman-α power spectrum—CMB lensing convergence cross-correlation

## Abstract

We investigate the three-point correlation between the Lyman-α forest and the CMB weak lensing (δ _{F}δ _{F}Κ) expressed as the cross-correlation between the CMB weak lensing field and local variations in the forest power spectrum. In addition to the standard gravitational bispectrum term, we note the existence of a non-standard systematic term coming from mis-estimation of the mean flux over the finite length of Lyman-α skewers. We numerically calculate the angular cross-power spectrum and discuss its features. We integrate it into zero-lag correlation function and compare our predictions with recent results by Doux et al.. We nd that our predictions are statistically consistent with the measurement, and including the systematic term improves the agreement with the measurement. We comment on the implication of the response of the Lyman-α forest power spectrum to the long-wavelength density perturbations.

- Authors:

- Stony Brook Univ., NY (United States)
- Brookhaven National Lab. (BNL), Upton, NY (United States)

- Publication Date:

- Research Org.:
- Brookhaven National Lab. (BNL), Upton, NY (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)

- OSTI Identifier:
- 1426439

- Report Number(s):
- BNL-203334-2018-JAAM

Journal ID: ISSN 1475-7516; TRN: US1802281

- Grant/Contract Number:
- SC0012704

- Resource Type:
- Journal Article: Accepted Manuscript

- Journal Name:
- Journal of Cosmology and Astroparticle Physics

- Additional Journal Information:
- Journal Volume: 2018; Journal Issue: 01; Journal ID: ISSN 1475-7516

- Publisher:
- Institute of Physics (IOP)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTRONOMY AND ASTROPHYSICS

### Citation Formats

```
Chiang, Chi-Ting, and Slosar, Anže.
```*The Lyman-α power spectrum—CMB lensing convergence cross-correlation*. United States: N. p., 2018.
Web. doi:10.1088/1475-7516/2018/01/012.

```
Chiang, Chi-Ting, & Slosar, Anže.
```*The Lyman-α power spectrum—CMB lensing convergence cross-correlation*. United States. doi:10.1088/1475-7516/2018/01/012.

```
Chiang, Chi-Ting, and Slosar, Anže. Thu .
"The Lyman-α power spectrum—CMB lensing convergence cross-correlation". United States.
doi:10.1088/1475-7516/2018/01/012.
```

```
@article{osti_1426439,
```

title = {The Lyman-α power spectrum—CMB lensing convergence cross-correlation},

author = {Chiang, Chi-Ting and Slosar, Anže},

abstractNote = {We investigate the three-point correlation between the Lyman-α forest and the CMB weak lensing (δFδFΚ) expressed as the cross-correlation between the CMB weak lensing field and local variations in the forest power spectrum. In addition to the standard gravitational bispectrum term, we note the existence of a non-standard systematic term coming from mis-estimation of the mean flux over the finite length of Lyman-α skewers. We numerically calculate the angular cross-power spectrum and discuss its features. We integrate it into zero-lag correlation function and compare our predictions with recent results by Doux et al.. We nd that our predictions are statistically consistent with the measurement, and including the systematic term improves the agreement with the measurement. We comment on the implication of the response of the Lyman-α forest power spectrum to the long-wavelength density perturbations.},

doi = {10.1088/1475-7516/2018/01/012},

journal = {Journal of Cosmology and Astroparticle Physics},

number = 01,

volume = 2018,

place = {United States},

year = {Thu Jan 11 00:00:00 EST 2018},

month = {Thu Jan 11 00:00:00 EST 2018}

}

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