Fermi-LAT Analysis of the Coma Cluster

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1 Fermi-LAT Analysis of the Coma Cluster a Fabio Zandanel GRAPPA Institute University of Amsterdam f.zandanel@uva.nl In collaboration with S. Ando (GRAPPA) 18 th Symposium on Astroparticle Physics in the Netherlands Leiden 23 th October 2013

2 Clusters of Galaxies Largest gravitationally bound systems in the Universe with mass of M and radius of few Mpc Actively evolving objects Cosmic energy reservoirs Expected to contain substantial populations of cosmic rays (CRs) and dark matter can generate non-thermal emission from radio to gamma-ray frequencies Powerful cosmological tools to test models on the origin and evolution of the Universe via thermal X-ray emission and Sunyaev-Zel dovich effect Fabio Zandanel (GRAPPA Amsterdam) 2

3 CRs in Clusters Processes & Emission from Pfrommer et al energy and particle sources structure formation AGNs and supernovae acceleration processes turbulence shock waves relativistic populations expected emission Fabio Zandanel (GRAPPA Amsterdam) 3

4 CRs in Clusters Processes & Emission from Pfrommer et al energy and particle sources structure formation AGNs and supernovae acceleration processes turbulence shock waves relativistic populations CR electrons re-acceleration primary CR electrons expected emission Fabio Zandanel (GRAPPA Amsterdam) 4

5 CRs in Clusters Processes & Emission from Pfrommer et al energy and particle sources structure formation AGNs and supernovae acceleration processes turbulence shock waves CR protons relativistic populations CR electrons re-acceleration primary CR electrons expected emission Fabio Zandanel (GRAPPA Amsterdam) 5

6 CRs in Clusters Processes & Emission from Pfrommer et al energy and particle sources structure formation AGNs and supernovae acceleration processes turbulence shock waves HADRONIC INTERACTIONS CR protons relativistic populations CR electrons re-acceleration primary CR electrons secondary CR electrons expected emission π Fabio Zandanel (GRAPPA Amsterdam) 6

7 CRs in Clusters Processes & Emission from Pfrommer et al energy and particle sources structure formation AGNs and supernovae acceleration processes turbulence shock waves HADRONIC INTERACTIONS CR protons relativistic populations CR electrons re-acceleration primary CR electrons secondary CR electrons expected emission synchrotron radio IC hard X-ray and gamma-ray π Fabio Zandanel (GRAPPA Amsterdam) 7

8 CRs in Clusters Processes & Emission from Pfrommer et al energy and particle sources structure formation AGNs and supernovae acceleration processes turbulence shock waves HADRONIC INTERACTIONS CR protons relativistic populations CR electrons re-acceleration primary CR electrons secondary CR electrons expected emission synchrotron radio IC hard X-ray and gamma-ray π 0 gamma-ray Fabio Zandanel (GRAPPA Amsterdam) 8

9 Analysis of Fermi-LAT data of the Coma Cluster FZ & Ando 2013, in preparation Analysis of 56 months of Fermi-LAT data on the Coma Cluster Events 100 MeV 100 GeV deg pixel = 0.1 deg We test different (diffuse) models: Point Source Disk Pinkze & Pfrommer (2010) FZ, Pfrommer & Prada (2012) Radio Relic template Ring-like Model (Keshet et al. 2012) NO DETECTION so far (TS 4) Fabio Zandanel (GRAPPA Amsterdam) 9

10 Analysis of Fermi-LAT data Templates FZ & Ando 2013, in preparation some TEMPLATES Fabio Zandanel (GRAPPA Amsterdam) 10

11 Analysis of Fermi-LAT data Results FZ & Ando 2013, in preparation Analysis of 56 months of Fermi-LAT data on the Coma Cluster Events 100 MeV 100 GeV deg pixel = 0.1 deg Model Fabio Zandanel (GRAPPA Amsterdam) 11

12 Analysis of Fermi-LAT data Results FZ & Ando 2013, in preparation Analysis of 56 months of Fermi-LAT data on the Coma Cluster Events 100 MeV 100 GeV deg pixel = 0.1 deg Model[%] Residuals Preliminary Fabio Zandanel (GRAPPA Amsterdam) 12

13 Analysis of Fermi-LAT data Implications Kushnir & Waxman (2009) predicted that a flat IC emission from primary electrons from accreting shocks should dominate the gamma-ray emission of clusters F TH >100 MEV cm -2 s -1 F UL >100 MEV cm -2 s Fabio Zandanel (GRAPPA Amsterdam) 13

14 Analysis of Fermi-LAT data Implications Kushnir & Waxman (2009) predicted that a flat IC emission from primary electrons from accreting shocks should dominate the gamma-ray emission of clusters F TH >100 MEV cm -2 s -1 F UL >100 MEV cm -2 s Electrons acceleration efficiency at shocks < 1% 2. However, likely overproduce radio emission Fabio Zandanel (GRAPPA Amsterdam) 14

15 Analysis of Fermi-LAT data Implications Keshet et al. (2012) claimed the detection of a gamma-ray ring around the Coma cluster in the VERITAS (Arlen et al. 2012) skymap, as predicted by earlier simulations (Keshet et al. 2003) F TH (>100 MEV) cm -2 s -1 F UL (>100 MEV) cm -2 s Fabio Zandanel (GRAPPA Amsterdam) 15

16 Analysis of Fermi-LAT data Implications Keshet et al. (2012) claimed the detection of a gamma-ray ring around the Coma cluster in the VERITAS (Arlen et al. 2012) skymap, as predicted by earlier simulations (Keshet et al. 2003) F TH (>100 MEV) cm -2 s -1 F UL (>100 MEV) cm -2 s No Ring-like structure is present 2. Electrons acceleration efficiency at shocks < 1% 3. Contribution to extragalactic background < 1% Fabio Zandanel (GRAPPA Amsterdam) 16

17 Analysis of Fermi-LAT data Implications Pinzke & Pfrommer (2010) predicted that pion decays from CR proton-proton interactions with the ambient gas should dominate the gamma-ray emission in clusters by running cosmological hydrodynamic simulations F TH >100 MEV cm -2 s -1 F UL >100 MEV cm -2 s Fabio Zandanel (GRAPPA Amsterdam) 17

18 Analysis of Fermi-LAT data Implications Pinzke & Pfrommer (2010) predicted that pion decays from CR proton-proton interactions with the ambient gas should dominate the gamma-ray emission in clusters by running cosmological hydrodynamic simulations F TH >100 MEV cm -2 s -1 F UL >100 MEV cm -2 s Protons maximum acceleration efficiency at shocks < 20% 2. CR-to-thermal pressure < 0.5% Fabio Zandanel (GRAPPA Amsterdam) 18

19 Analysis of Fermi-LAT data Implications FZ, Pfrommer & Prada (2012) included the possible CR transport phenomena (streaming and diffusion) by merging the advection-dominated simulations (Pinzke & Pfrommer 2010) and analytical (Ensslin et al. 2011) approaches Advection-dominated regime: F TH >100 MEV cm -2 s -1 F UL >100 MEV cm -2 s -1 Streaming-dominated regime: F TH >100 MEV cm -2 s -1 F UL >100 MEV cm -2 s Fabio Zandanel (GRAPPA Amsterdam) 19

20 Analysis of Fermi-LAT data Implications FZ, Pfrommer & Prada (2012) included the possible CR transport phenomena (streaming and diffusion) by merging the advection-dominated simulations (Pinzke & Pfrommer 2010) and analytical (Ensslin et al. 2011) approaches Advection-dominated regime: F TH >100 MEV cm -2 s -1 F UL >100 MEV cm -2 s Protons maximum acceleration efficiency at shocks < 20% 2. Overproduce radio for B 0 5 μg max. acc. eff. 5% Streaming-dominated regime: F TH >100 MEV cm -2 s -1 F UL >100 MEV cm -2 s -1 Being challenged, assuming magnetic field from Faraday rotation measurements (B 0 5 μg, α B = 0.5) but Fabio Zandanel (GRAPPA Amsterdam) 20

21 Conclusions & Future Prospects Gamma-rays (Fermi & IACTs) are starting to put stringent constraints on various acceleration scenarios and on the CR content in clusters of galaxies Detection of cluster gamma-ray emission would be a major scientific discovery Fermi 10 yr CTA Open up a new window to study: non-thermal processes in clusters high-energy physics in the largest and latest structures DM, CR, ICM, and cluster magnetic field formation and evolution of clusters and of the Universe itself Fabio Zandanel (GRAPPA Amsterdam) 21

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24 Gamma-ray Spectrum (Pinzke & Pfrommer 2010) Fabio Zandanel (GRAPPA Amsterdam) 24