Search for gamma-ray emission from the Coma Cluster with six years of Fermi-LAT data
Abstract
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.
Related
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- Search for Gamma-ray emission from Abell 119 galaxy cluster using INTEGRAL/ISGRI, COMPTEL, and DAMPE data
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BibTeX
@article{ackermann2026search,
title = {{Search for gamma-ray emission from the Coma Cluster with six years of Fermi-LAT data}},
author = {M. Ackermann and M. Ajello and A. Albert and W.B. Atwood and L. Baldini and J. Ballet and G. Barbiellini and D. Bastieri and K. Bechtol and R. Bellazzini and E. Bissaldi and R.D. Blandford and E.D. Bloom and R. Bonino and E. Bottacini and J. Bregeon and P. Bruel and R. Buehler and G.A. Caliandro and R.A. Cameron and M. Caragiulo and P.A. Caraveo and J.M. Casandjian and E. Cavazzuti and C. Cecchi and E. Charles and A. Chekhtman and G. Chiaro and S. Ciprini and Johann Cohen-Tanugi and J. Conrad and S. Cutini and F. d'Ammando and A.De Angelis and F.De Palma and R. Desiante and S.W. Digel and L.Di Venere and P.S. Drell and C. Favuzzi and S.J. Fegan and Y. Fukazawa and S. Funk and P. Fusco and F. Gargano and D. Gasparrini and N. Giglietto and F. Giordano and M. Giroletti and G. Godfrey and D. Green and I.A. Grenier and S. Guiriec and E. Hays and J.W. Hewitt and D. Horan and G. Jóhannesson and M. Kuss and S. Larsson and L. Latronico},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/0004-637x/819/2/149},
eprint = {1507.08995},
archivePrefix = {arXiv},
url = {https://hal.science/hal-01823268v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Search for gamma-ray emission from the Coma Cluster with six years of Fermi-LAT data
AU - M. Ackermann
AU - M. Ajello
AU - A. Albert
AU - W.B. Atwood
AU - L. Baldini
AU - J. Ballet
AU - G. Barbiellini
AU - D. Bastieri
AU - K. Bechtol
AU - R. Bellazzini
AU - E. Bissaldi
AU - R.D. Blandford
AU - E.D. Bloom
AU - R. Bonino
AU - E. Bottacini
AU - J. Bregeon
AU - P. Bruel
AU - R. Buehler
AU - G.A. Caliandro
AU - R.A. Cameron
AU - M. Caragiulo
AU - P.A. Caraveo
AU - J.M. Casandjian
AU - E. Cavazzuti
AU - C. Cecchi
AU - E. Charles
AU - A. Chekhtman
AU - G. Chiaro
AU - S. Ciprini
AU - Johann Cohen-Tanugi
AU - J. Conrad
AU - S. Cutini
AU - F. d'Ammando
AU - A.De Angelis
AU - F.De Palma
AU - R. Desiante
AU - S.W. Digel
AU - L.Di Venere
AU - P.S. Drell
AU - C. Favuzzi
AU - S.J. Fegan
AU - Y. Fukazawa
AU - S. Funk
AU - P. Fusco
AU - F. Gargano
AU - D. Gasparrini
AU - N. Giglietto
AU - F. Giordano
AU - M. Giroletti
AU - G. Godfrey
AU - D. Green
AU - I.A. Grenier
AU - S. Guiriec
AU - E. Hays
AU - J.W. Hewitt
AU - D. Horan
AU - G. Jóhannesson
AU - M. Kuss
AU - S. Larsson
AU - L. Latronico
PY - 2026
DA - 2026/10/30
JO - The Astrophysical Journal
DO - 10.3847/0004-637x/819/2/149
UR - https://hal.science/hal-01823268v1
AB - 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.
SN - 0004-637X
SN - 1538-4357
ER -