# Impact of spurious shear on cosmological parameter estimates from weak lensing observables

## Abstract

We research, residual errors in shear measurements, after corrections for instrument systematics and atmospheric effects, can impact cosmological parameters derived from weak lensing observations. Here we combine convergence maps from our suite of ray-tracing simulations with random realizations of spurious shear. This allows us to quantify the errors and biases of the triplet (Ω _{m},w,σ _{8}) derived from the power spectrum (PS), as well as from three different sets of non-Gaussian statistics of the lensing convergence field: Minkowski functionals (MFs), low-order moments (LMs), and peak counts (PKs). Our main results are as follows: (i) We find an order of magnitude smaller biases from the PS than in previous work. (ii) The PS and LM yield biases much smaller than the morphological statistics (MF, PK). (iii) For strictly Gaussian spurious shear with integrated amplitude as low as its current estimate of σ _{sys} ^{2} ≈ 10 ^{-7}, biases from the PS and LM would be unimportant even for a survey with the statistical power of Large Synoptic Survey Telescope. However, we find that for surveys larger than ≈ 100 deg ^{2}, non-Gaussianity in the noise (not included in our analysis) will likely be important and must be quantified to assess themore »

- Authors:

- Columbia Univ., New York, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Columbia Univ., New York, NY (United States)
- Univ. of KwaZulu-Natal, Durban (South Africa)

- Publication Date:

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

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

- OSTI Identifier:
- 1174106

- Alternate Identifier(s):
- OSTI ID: 1181166

- Report Number(s):
- BNL-107477-2015-JA

Journal ID: ISSN 1550-7998; PRVDAQ; KA2301020

- Grant/Contract Number:
- SC00112704; AC02-98CH10886

- Resource Type:
- Journal Article: Accepted Manuscript

- Journal Name:
- Physical Review. D, Particles, Fields, Gravitation and Cosmology

- Additional Journal Information:
- Journal Volume: 90; Journal Issue: 12; Journal ID: ISSN 1550-7998

- Publisher:
- American Physical Society (APS)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTRONOMY AND ASTROPHYSICS; weak gravitational lensing; data analysis; analytical; numerical; statistical

### Citation Formats

```
Petri, Andrea, May, Morgan, Haiman, Zoltán, and Kratochvil, Jan M.
```*Impact of spurious shear on cosmological parameter estimates from weak lensing observables*. United States: N. p., 2014.
Web. doi:10.1103/PhysRevD.90.123015.

```
Petri, Andrea, May, Morgan, Haiman, Zoltán, & Kratochvil, Jan M.
```*Impact of spurious shear on cosmological parameter estimates from weak lensing observables*. United States. doi:10.1103/PhysRevD.90.123015.

```
Petri, Andrea, May, Morgan, Haiman, Zoltán, and Kratochvil, Jan M. Tue .
"Impact of spurious shear on cosmological parameter estimates from weak lensing observables". United States.
doi:10.1103/PhysRevD.90.123015. https://www.osti.gov/servlets/purl/1174106.
```

```
@article{osti_1174106,
```

title = {Impact of spurious shear on cosmological parameter estimates from weak lensing observables},

author = {Petri, Andrea and May, Morgan and Haiman, Zoltán and Kratochvil, Jan M.},

abstractNote = {We research, residual errors in shear measurements, after corrections for instrument systematics and atmospheric effects, can impact cosmological parameters derived from weak lensing observations. Here we combine convergence maps from our suite of ray-tracing simulations with random realizations of spurious shear. This allows us to quantify the errors and biases of the triplet (Ωm,w,σ8) derived from the power spectrum (PS), as well as from three different sets of non-Gaussian statistics of the lensing convergence field: Minkowski functionals (MFs), low-order moments (LMs), and peak counts (PKs). Our main results are as follows: (i) We find an order of magnitude smaller biases from the PS than in previous work. (ii) The PS and LM yield biases much smaller than the morphological statistics (MF, PK). (iii) For strictly Gaussian spurious shear with integrated amplitude as low as its current estimate of σsys2 ≈ 10-7, biases from the PS and LM would be unimportant even for a survey with the statistical power of Large Synoptic Survey Telescope. However, we find that for surveys larger than ≈ 100 deg2, non-Gaussianity in the noise (not included in our analysis) will likely be important and must be quantified to assess the biases. (iv) The morphological statistics (MF, PK) introduce important biases even for Gaussian noise, which must be corrected in large surveys. The biases are in different directions in (Ωm,w,σ8) parameter space, allowing self-calibration by combining multiple statistics. Our results warrant follow-up studies with more extensive lensing simulations and more accurate spurious shear estimates.},

doi = {10.1103/PhysRevD.90.123015},

journal = {Physical Review. D, Particles, Fields, Gravitation and Cosmology},

number = 12,

volume = 90,

place = {United States},

year = {Tue Dec 30 00:00:00 EST 2014},

month = {Tue Dec 30 00:00:00 EST 2014}

}

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