Constraining the population of cosmic ray protons in cooling flow clusters with γ-ray and radio observations: Are radio mini-halos of hadronic origin?

Details Constraining the population of cosmic ray protons in cooling flow clusters with γ-ray and radio observations: Are radio mini-halos of hadronic origin? Constraining the population of cosmic ray protons in cooling flow clusters with γ-ray and radio observations: Are radio mini-halos of hadronic origin?

Jan 2004

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004a%26a...413...17p&link_type=abstract

Astronomy and Astrophysics, v.413, p.17-36 (2004)

Astronomy and Astrophysics

Astrophysics

111

Galaxies: Cooling Flows, Galaxies: Cluster: General, Galaxies: Cluster: Individual: Perseus (A426), Galaxies: Intergalactic Medium, Ism: Cosmic Rays, Radiation Mechanisms: Non-Thermal

Scientific paper

We wish to constrain the cosmic-ray proton (CRp) population in galaxy clusters. By hadronic interactions with the thermal gas of the intra-cluster medium (ICM), the CRp produce γ-rays for which we develop an analytic formalism to deduce their spectral distribution. Assuming the CRp-to-thermal energy density ratio XCRp and the CRp spectral index to be spatially constant, we derive an analytic relation between the γ-ray and bolometric X-ray fluxes, Fγ and FX. Based on our relation, we compile a sample of suitable clusters which are promising candidates for future detection of γ-rays resulting from hadronic CRp interactions. Comparing to EGRET upper limits, we constrain the CRp population in the cooling flow clusters Perseus and Virgo to XCRp < 20%. Assuming a plausible value for the CRp diffusion coefficient κ, we find the central CRp injection luminosity of M 87 to be limited to 1043 erg s-1 κ/(1029 cm2 s-1). The synchrotron emission from secondary electrons generated in CRp hadronic interactions allows even tighter limits to be placed on the CRp population using radio observations. We obtain excellent agreement between the observed and theoretical radio brightness profiles for Perseus, but not for Coma without a radially increasing CRp-to-thermal energy density profile. Since the CRp and magnetic energy densities necessary to reproduce the observed radio flux are very plausible, we propose synchrotron emission from secondary electrons as an attractive explanation of the radio mini-halos found in cooling flow clusters. This model can be tested with future sensitive γ-ray observations of the accompanying pi0-decays. We identify Perseus (A 426), Virgo, Ophiuchus, and Coma (A 1656) as the most promising candidate clusters for such observations.

Affiliated with

Also associated with

No associations

Rating

Constraining the population of cosmic ray protons in cooling flow clusters with γ-ray and radio observations: Are radio mini-halos of hadronic origin? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Constraining the population of cosmic ray protons in cooling flow clusters with γ-ray and radio observations: Are radio mini-halos of hadronic origin?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Constraining the population of cosmic ray protons in cooling flow clusters with γ-ray and radio observations: Are radio mini-halos of hadronic origin? will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1837444