Abstract
Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated and, on account of weak energy losses, can accumulate, suggesting that clusters may also be sources of very high energy (VHE; E 100 GeV) gamma-ray emission. We report here on VHE gamma-ray observations of the Coma galaxy cluster with the VERITAS array of imaging Cerenkov telescopes, with complementing Fermi Large Area Telescope observations at GeV energies. No significant gamma-ray emission from the Coma Cluster was detected. Integral flux upper limits at the 99% confidence level were measured to be on the order of (2-5) x 10(-8) photonsm(-2) s(-1) (VERITAS, 220 GeV) and similar to 2 x 10(-6) photonsm(-2) s(-1) (Fermi, 1-3GeV), respectively. We use the gamma-ray upper limits to constrain cosmic rays (CRs) and magnetic fields in Coma. Using an analytical approach, the CR-to-thermal pressure ratio is constrained to be .
| Original language | English (Ireland) |
|---|---|
| Article number | 123 |
| Journal | Astrophysical Journal |
| Volume | 757 |
| Issue number | 2 |
| Publication status | Published - 1 Oct 2012 |
Keywords
- cosmic rays
- dark matter
- galaxies: clusters: general
- galaxies: clusters: individual (Coma (ACO 1656))
- gamma rays: galaxies: clusters
- magnetic fields
Authors (Note for portal: view the doc link for the full list of authors)
- Authors
- Arlen, T,Aune, T,Beilicke, M,Benbow, W,Bouvier, A,Buckley, JH,Bugaev, V,Byrum, K,Cannon, A,Cesarini, A,Ciupik, L,Collins-Hughes, E,Connolly, MP,Cui, W,Dickherber, R,Dumm, J,Falcone, A,Federici, S,Feng, Q,Finley, JP,Finnegan, G,Fortson, L,Furniss, A,Galante, N,Gall, D,Godambe, S,Griffin, S,Grube, J,Gyuk, G,Holder, J,Huan, H,Hughes, G,Humensky, TB,Imran, A,Kaaret, P,Karlsson, N,Kertzman, M,Khassen, Y,Kieda, D,Krawczynski, H,Krennrich, F,Lee, K,Madhavan, AS,Maier, G,Majumdar, P,McArthur, S,McCann, A,Moriarty, P,Mukherjee, R,Nelson, T,de Bhroithe, AO,Ong, RA,Orr, M,Otte, AN,Park, N,Perkins, JS,Pohl, M,Prokoph, H,Quinn, J,Ragan, K,Reyes, LC,Reynolds, PT,Roache, E,Ruppel, J,Saxon, DB,Schroedter, M,Sembroski, GH,Skole, C,Smith, AW,Telezhinsky, I,Tesic, G,Theiling, M,Thibadeau, S,Tsurusaki, K,Var