Impact of Baryonic Processes on Weak-Lensing Cosmology: Power Spectrum, Nonlocal Statistics, and Parameter Bias

Abstract

We study the impact of baryonic physics on cosmological parameter estimation with weak-lensing surveys. We run a set of cosmological hydrodynamics simulations with different galaxy formation models. We then perform raytracing simulations through the total matter density field to generate 100 independent convergence maps with a field of view of 25 deg 2 , and we use them to examine the ability of the following three lensing statistics as cosmological probes:power spectrum (PS), peak counts, and Minkowski functionals (MFs). For the upcoming wide-field observations, such as the Subaru Hyper Suprime-Cam (HSC) survey with a sky coverage of 1400 deg 2 , these three statistics provide tight constraints on the matter density, density fluctuation amplitude, and dark energy equation of state, but parameter bias is induced by baryonic processes such as gas cooling and stellar feedback. When we use PS, peak counts, and MFs, the magnitude of relative bias in the dark energy equation of state parameter w is at a level of, respectively, w 0.017 d~, 0.061, and 0.0011. For the HSC survey, these values are smaller than the statistical errors estimated from Fisher analysis. The bias could be significant when the statistical errors become small in future observations with a much larger survey area. We find that the bias is induced in different directions in the parameter space depending on the statistics employed. While the two-point statistic, i.e., PS, yields robust results against baryonic effects, the overall constraining power is weak compared with peak counts and MFs. On the other hand, using one of peak counts or MFs, or combined analysis with multiple statistics, results in a biased parameter estimate. The bias can be as large as 1σ for the HSC surveyand will be more significant for upcoming wider-area surveys. We suggest to use an optimized combination so that the baryonic effects on parameter estimation are mitigated. Such a "calibrated" combination can place stringent and robust constraints on cosmological parameters.

KiDS-450: cosmological constraints from weak lensing peak statistics – I. Inference from analytical prediction of high signal-to-noise ratio convergence peaks

“…On the other hand, including the feedback of supernovae, stars and AGNs, Osato et al (2015) find that the feedback effects can effectively reduce the mass of small DM haloes, eventually reducing the number of low-SNR WL peaks. Because of the smaller impact of feedback on the massive DM haloes (Velliscig et al 2014), the high-SNR peak number is not significantly changed.…”

“…Indeed, most of the low signal-to-noise ratio (SNR) peaks are usually not associated with a dominant halo, and are instead generated by the projection of LSS along the LOS. Even for high-SNR peaks where the correspondence with massive haloes is clearly seen, many systematic effects, such as the shape noise contamination from the intrinsic ellipticities of source galaxies, the boost factor due to the member contamination and the blending in cluster regions, baryonic effects, the projection effects of LSS, and intrinsic alignments (IA), can complicate WL peak analysis (Tang & Fan 2005;Yang et al 2011Yang et al , 2013Hamana et al 2012;Fu & Fan 2014;Osato et al 2015;Kacprzak et al 2016;Liu & Haiman 2016;Yuan et al 2017). These can generate non-halo-associated peaks and also alter the significance of the peaks from DM haloes, thus affecting WL peak statistics.…”

Full-sky Gravitational Lensing Simulation for Large-area Galaxy Surveys and Cosmic Microwave Background Experiments

“…AGN feedback also suppresses the number density of halos by a few tens of a percent at M 10 14 M ⊙ (Vogelsberger et al 2014a). Current and future weak-lensing surveys will detect such baryonic effects via the shear correlation functions, convergence peak counts, or Minkowski functionals (e.g., Semboloni et al 2011;Osato et al 2015). These baryonic effects on the matter power spectrum can be taken into account using the fitting formula given by .…”

Origin of weak lensing convergence peaks

“…Refs. [9,34] studied the impact of baryonic physics on peaks, which can change the matter distribution inside dark matter halos through radiative cooling and feedback. Our findings are consistent with Y11 and suggest that low peaks may be less affected by baryonic processes, which may be confined to the inner regions of the halo ( [17], although see [18] that AGN feedback can impact the gas distribution out to the virial radius and beyond).…”