Correlation of extragalactic γ rays with cosmic matter density distributions from weak gravitational lensing

Abstract

The extragalactic γ-ray background (EGB) arises from the accumulation of γ-ray emissions from resolved and unresolved extragalactic sources as well as diffuse processes. It is important to study the statistical properties of the EGB in the context of cosmological structure formation. Known astrophysical γ-ray sources such as blazars, star-forming galaxies, and radio galaxies are expected to trace the underlying cosmic matter density distribution. We explore the correlation of the EGB from Fermi-LAT data with the large-scale matter density distribution from the Subaru Hyper Suprime-Cam (HSC) SSP survey. We reconstruct an unbiased surface matter density distribution κ at z < ∼ 1 by applying weak-gravitational lensing analysis to the first-year HSC data. We then calculate the γ − κ cross-correlation. Our measurements are consistent with a null detection, but a weak correlation is found at angular scales of 30-60 arcmin, especially when distant source galaxies at z > 1 are used for the lensing κ reconstruction. The large-scale correlation suggests strong clustering of high-redshift γ-ray sources such as blazars. However, the inferred bias factor of 4 − 5 is larger by about a factor of two than results from other clustering analyses. The final HSC data covering 1,400 squared degrees will play an essential role to determine accurately the blazar bias at z > 0.5.

Probing heavy dark matter decays with multi-messenger astrophysical data

“…In addition, we find that for 10 13 GeV m dm 10 16 GeV the PAO constraints are comparable to those obtained with Fermi-LAT. Although the constraints obtained with our extragalactic predictions are found to be weaker than those using the Galactic component, our simulations could potentially be used in future analyses of all sky gamma-ray analyses of, for example, tomographic cross-correlation using the local galaxy distributions [83][84][85][86][87][88].…”

Cross-correlation of the extragalactic gamma-ray background with the thermal Sunyaev-Zel’dovich effect in the cosmic microwave background

“…This is because faint blazar populations can be responsible for the UGRB at gamma-ray energies larger than ∼10 GeV, while mAGNs can contribute significantly to the UGRB at ∼1 GeV [86]. Also, blazars and mAGNs likely reside in massive dark matter halos (e.g., Refs [87][88][89]). The star forming activity in clusters can be a source of gamma rays in principle [90]; however, we ignore this contribution in this paper.…”

“…To evaluate the correlation between the gamma-ray emission from blazars and the tSZ effect by the ICM, we adopt the blazar model in Ref. [89]. In this model, the blazar is assumed to be a point source and located at the center of a dark matter halo.…”

Photometric Redshifts for the Hyper Suprime-Cam Subaru Strategic Program Data Release 2

“…The secound data release of the HSC photo-z has been published in January 31st, 2020 which is based on the photometric data collected from 2014 February to August 2018. To date, the HSC photoz has been widely utilized in various sciences; cluster of galaxies (Lin et al 2017;Miyaoka et al 2018;Miyazaki et al 2018;Jian et al 2018;Toshikawa et al 2018;Medezinski et al 2018;Yamashita et al 2018;Miyatake et al 2019;Kondo et al 2019;Pintos-Castro et al 2019;Okabe et al 2019b;Chiu et al 2019;Umetsu et al 2019;Murata et al 2019;Okabe et al 2019a;Hayashi et al 2019;Osato et al 2020), cosmoc weak and strong lensing analysis (Oguri et al 2018;Shirasaki et al 2018;Wong et al 2018;Sonnenfeld et al 2018;Sonnenfeld et al 2019;Hikage et al 2019;Hamana et al 2019;Sakakibara et al 2019;Namikawa et al 2019;Li et al 2019;Speagle et al 2019), and galaxy and quasar studies (Onoue et al 2018;Koyama et al 2018;He et al 2018;Yamashita et al 2018;Sonnenfeld et al 2019;Noboriguchi et al 2019;Pintos-Castro et al 2019;Wong et al 2019;Toba et al 2019;…”