Gamma Rays From Star Formation in Clusters of Galaxies

Storm, Emma; Jeltema, T.; Profumo, Stefano

doi:10.1088/0004-637x/755/2/117

Cited by 12 publications

(12 citation statements)

References 42 publications

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“…The other discrete ("compact") sources are mostly from starforming galaxies, whose contribution to the cluster γ-ray emission was estimated by Storm et al (2012) based on a scaling relation between galactic IR and γ-ray emission. They estimated that the superposed 0.1-100 GeV luminosity of starforming galaxies in Coma is in the wide range of ∼3×10 40 -3×10 42 erg s −1 .…”

Section: Discussionmentioning

confidence: 99%

Search for Gamma-Ray Emission From the Coma Cluster With Six Years of Fermi-Lat Data

Ackermann¹,

Ajello²,

Albert³

et al. 2016

ApJ

109

118

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We present results from γ-ray observations of the Coma cluster incorporating six years of Fermi-LAT data and the newly released "Pass 8" event-level analysis. Our analysis of the region reveals low-significance residual structures within the virial radius of the cluster that are too faint for a detailed investigation with the current data. Using a likelihood approach that is free of assumptions on the spectral shape we derive upper limits on the γ-ray flux that is expected from energetic particle interactions in the cluster. We also consider a benchmark spatial and spectral template motivated by models in which the observed radio halo is mostly emission by secondary electrons. In this case, the median expected and observed upper limits for the flux above 100 MeV are 1.7×10 −9 ph cm −2 s −1 and 5.2×10 −9 ph cm −2 s −1 respectively (the latter corresponds to residual emission at the level of 1.8σ). These bounds are comparable to or higher than predicted levels of hadronic gamma-ray emission in cosmic-ray (CR) models with or without reacceleration of secondary electrons, although direct comparisons are sensitive to assumptions regarding the origin and propagation mode of CRs and magnetic field properties. The minimal expected γ-ray flux from radio and star-forming galaxies within the Coma cluster is roughly an order of magnitude below the median sensitivity of our analysis.

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Section: Discussionmentioning

confidence: 99%

Search for Gamma-Ray Emission From the Coma Cluster With Six Years of Fermi-Lat Data

Ackermann¹,

Ajello²,

Albert³

et al. 2016

ApJ

109

118

View full text Add to dashboard Cite

show abstract

“…In this paper, we focus on the CR-induced γ -ray signal and defer an analysis of γ rays originating from DM decay or annihilation to future studies. For a study of γ rays originating from star-forming galaxies in galaxy clusters, see, e.g., Storm et al (2012). Hydrodynamic simulations of galaxy clusters in a cosmological framework that include CR physics show an approximately universal spectral and spatial CR distribution within clusters as a result of hierarchical structure growth (Pinzke & Pfrommer 2010).…”

Section: Signal Model: Gamma-ray Emission From Cosmic Raysmentioning

confidence: 99%

Search for Cosmic-Ray-Induced Gamma-Ray Emission in Galaxy Clusters

Ackermann¹,

Ajello²,

Albert³

et al. 2014

ApJ

144

146

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Current theories predict relativistic hadronic particle populations in clusters of galaxies in addition to the already observed relativistic leptons. In these scenarios hadronic interactions give rise to neutral pions which decay into γ rays that are potentially observable with the Large Area Telescope (LAT) on board the Fermi space telescope. We present a joint likelihood analysis searching for spatially extended γ-ray emission at the locations of 50 galaxy clusters in four years of Fermi-LAT data under the assumption of the universal cosmic-ray (CR) model proposed by Pinzke & Pfrommer. We find an excess at a significance of 2.7σ , which upon closer inspection, however, is correlated to individual excess emission toward three galaxy clusters: A400, A1367, and A3112. We discuss these cases in detail and conservatively attribute the emission to unmodeled background systems (for example, radio galaxies within the clusters).Through the combined analysis of 50 clusters, we exclude hadronic injection efficiencies in simple hadronic models above 21% and establish limits on the CR to thermal pressure ratio within the virial radius, R 200 , to be below 1.25%-1.4% depending on the morphological classification. In addition, we derive new limits on the γ-ray flux from individual clusters in our sample.

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“…The other discrete ('compact') sources are mostly from star-forming galaxies, whose contribution to the cluster γray emission was estimated by Storm et al (2012) based on a scaling relation between galactic IR and γ-ray emission. They estimated that the superposed 0.1 − 100 GeV luminosity of star-forming galaxies in Coma is in the wide range of ∼ 3 × 10 40 − 3 × 10 42 erg s −1 .…”

Section: Discussionmentioning

confidence: 99%

Erratum: “Search for Gamma-Ray Emission from the Coma Cluster with Six Years of Fermi-LAT Data” (2016, ApJ, 819, 149)

Ackermann

Ajello

Albert

et al. 2018

ApJ

View full text Add to dashboard Cite

We present results from γ-ray observations of the Coma cluster incorporating 6 years of Fermi-LAT data and the newly released "Pass 8" event-level analysis. Our analysis of the region reveals low-significance residual structures within the virial radius of the cluster that are too faint for a detailed investigation with the current data. Using a likelihood approach that is free of assumptions on the spectral shape we derive upper limits on the γ-ray flux that is expected from energetic particle interactions in the cluster. We also consider a benchmark spatial and spectral template motivated by models in which the observed radio halo is mostly emission by secondary electrons. In this case, the median expected and observed upper limits for the flux above 100 MeV are 1.7 × 10 −9 ph cm −2 s −1 and 5.2 × 10 −9 ph cm −2 s −1 respectively (the latter corresponds to residual emission at the level of 1.8σ). These bounds are comparable to or higher than predicted levels of hadronic gamma-ray emission in cosmic-ray models with or without reacceleration of secondary electrons, although direct comparisons are sensitive to assumptions regarding the origin and propagation mode of cosmic rays and magnetic field properties. The minimal expected γ-ray flux from radio and star-forming galaxies within the Coma cluster is roughly an order of magnitude below the median sensitivity of our analysis.

show abstract

Gamma Rays From Star Formation in Clusters of Galaxies

Cited by 12 publications

References 42 publications

Search for Gamma-Ray Emission From the Coma Cluster With Six Years of Fermi-Lat Data

Search for Gamma-Ray Emission From the Coma Cluster With Six Years of Fermi-Lat Data

Search for Cosmic-Ray-Induced Gamma-Ray Emission in Galaxy Clusters

Erratum: “Search for Gamma-Ray Emission from the Coma Cluster with Six Years of Fermi-LAT Data” (2016, ApJ, 819, 149)

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