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Title: CROSS-CORRELATING THE γ-RAY SKY WITH CATALOGS OF GALAXY CLUSTERS

Abstract

In this article, we report the detection of a cross-correlation signal between Fermi Large Area Telescope diffuse γ-ray maps and catalogs of clusters. In our analysis, we considered three different catalogs: WHL12, redMaPPer, and PlanckSZ. They all show a positive correlation with different amplitudes, related to the average mass of the objects in each catalog, which also sets the catalog bias. The signal detection is confirmed by the results of a stacking analysis. The cross-correlation signal extends to rather large angular scales, around 1°, that correspond, at the typical redshift of the clusters in these catalogs, to a few to tens of megaparsecs, i.e., the typical scale-length of the large-scale structures in the universe. Most likely this signal is contributed by the cumulative emission from active galactic nuclei (AGNs) associated with the filamentary structures that converge toward the high peaks of the matter density field in which galaxy clusters reside. In addition, our analysis reveals the presence of a second component, more compact in size and compatible with a point-like emission from within individual clusters. At present, we cannot distinguish between the two most likely interpretations for such a signal, i.e., whether it is produced by AGNs inside clusters ormore » if it is a diffuse γ-ray emission from the intracluster medium. Lastly, we argue that this latter, intriguing, hypothesis might be tested by applying this technique to a low-redshift large-mass cluster sample.« less

Authors:
ORCiD logo [1]; ORCiD logo [2];  [3]; ORCiD logo [4]; ORCiD logo [4];  [5];  [6]
  1. Universita degli Studi Roma Tre (Italy); INFN, Sezione di Roma Tre (Italy); INAF Osservatorio Astronomico di Roma, Osservatorio Astronomico di Roma (Italy)
  2. The University of Manchester, Alan Turing Building (United Kingdom). Jodrell Bank Centre for Astrophysics
  3. RWTH Aachen University (Germany). Institute for Theoretical Particle Physics and Cosmology
  4. Universita di Torino (Italy). Dipartimento di Fisica; Istituto Nazionale di Fisica Nucleare, Sezione di Torino (Italy)
  5. INAF Osservatorio Astronomico di Trieste (Italy); SISSA-International School for Advanced Studies, Trieste (Italy); INFN, Sezione di Trieste (Italy)
  6. Beijing Normal University (China). Department of Astronomy
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
Fermi LAT Collaboration
OSTI Identifier:
1355746
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
The Astrophysical Journal. Supplement Series (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal. Supplement Series (Online); Journal Volume: 228; Journal Issue: 1; Journal ID: ISSN 1538-4365
Publisher:
American Astronomical Society/IOP
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; cosmology; observations; theory; gamma-rays; diffuse backgrounds; large-scale structure of universe

Citation Formats

Branchini, Enzo, Camera, Stefano, Cuoco, Alessandro, Fornengo, Nicolao, Regis, Marco, Viel, Matteo, and Xia, Jun-Qing. CROSS-CORRELATING THE γ-RAY SKY WITH CATALOGS OF GALAXY CLUSTERS. United States: N. p., 2017. Web. doi:10.3847/1538-4365/228/1/8.
Branchini, Enzo, Camera, Stefano, Cuoco, Alessandro, Fornengo, Nicolao, Regis, Marco, Viel, Matteo, & Xia, Jun-Qing. CROSS-CORRELATING THE γ-RAY SKY WITH CATALOGS OF GALAXY CLUSTERS. United States. doi:10.3847/1538-4365/228/1/8.
Branchini, Enzo, Camera, Stefano, Cuoco, Alessandro, Fornengo, Nicolao, Regis, Marco, Viel, Matteo, and Xia, Jun-Qing. Wed . "CROSS-CORRELATING THE γ-RAY SKY WITH CATALOGS OF GALAXY CLUSTERS". United States. doi:10.3847/1538-4365/228/1/8. https://www.osti.gov/servlets/purl/1355746.
@article{osti_1355746,
title = {CROSS-CORRELATING THE γ-RAY SKY WITH CATALOGS OF GALAXY CLUSTERS},
author = {Branchini, Enzo and Camera, Stefano and Cuoco, Alessandro and Fornengo, Nicolao and Regis, Marco and Viel, Matteo and Xia, Jun-Qing},
abstractNote = {In this article, we report the detection of a cross-correlation signal between Fermi Large Area Telescope diffuse γ-ray maps and catalogs of clusters. In our analysis, we considered three different catalogs: WHL12, redMaPPer, and PlanckSZ. They all show a positive correlation with different amplitudes, related to the average mass of the objects in each catalog, which also sets the catalog bias. The signal detection is confirmed by the results of a stacking analysis. The cross-correlation signal extends to rather large angular scales, around 1°, that correspond, at the typical redshift of the clusters in these catalogs, to a few to tens of megaparsecs, i.e., the typical scale-length of the large-scale structures in the universe. Most likely this signal is contributed by the cumulative emission from active galactic nuclei (AGNs) associated with the filamentary structures that converge toward the high peaks of the matter density field in which galaxy clusters reside. In addition, our analysis reveals the presence of a second component, more compact in size and compatible with a point-like emission from within individual clusters. At present, we cannot distinguish between the two most likely interpretations for such a signal, i.e., whether it is produced by AGNs inside clusters or if it is a diffuse γ-ray emission from the intracluster medium. Lastly, we argue that this latter, intriguing, hypothesis might be tested by applying this technique to a low-redshift large-mass cluster sample.},
doi = {10.3847/1538-4365/228/1/8},
journal = {The Astrophysical Journal. Supplement Series (Online)},
number = 1,
volume = 228,
place = {United States},
year = {Wed Jan 18 00:00:00 EST 2017},
month = {Wed Jan 18 00:00:00 EST 2017}
}

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