Doron Kushnir

Magnetic fields and cosmic rays in clusters of galaxies

We argue that the observed correlation between the radio luminosity and the thermal X-ray luminosity of radio emitting galaxy clusters implies that the radio emission is due to secondary electrons that are produced by p-p interactions and lose their energy by emitting synchrotron radiation in a strong magnetic field, B > (8πaTCMB4)1/2 3 μG. We construct a simple model that naturally explains the correlation, and show that the observations provide stringent constraints on cluster magnetic fields and cosmic rays (CRs): Within the cores of clusters, the ratio βcore between the CR energy (per logarithmic particle energy interval) and the thermal energy is βcore ~ 2 10−4; The source of these CRs is most likely the cluster accretion shock, which is inferred to deposit in CRs ~ 0.1 of the thermal energy it generates; The diffusion time of 100 GeV CRs over scales 100 kpc is not short compared to the Hubble time; Cluster magnetic fields are enhanced by mergers to 1% of equipartition, and decay (to < 1 μG) on 1 Gyr time scales. The inferred value of βcore implies that high energy gamma-ray emission from secondaries at cluster cores will be difficult to detect with existing and planned instruments.

Constraints on the ejecta of the GW170817 neutron-star merger from its electromagnetic emission

We present a simple analytic model, that captures the key features of the emission of radiation from material ejected by the merger of neutron stars (NS), and construct the multi-band and bolometric luminosity light curves of the transient associated with GW 170817, AT 2017gfo, using all available data. The UV to IR emission is shown to be consistent with a single

The stability of decelerating shocks revisited

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HARD X-RAY EMISSION FROM ACCRETION SHOCKS AROUND GALAXY CLUSTERS

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The expected spins of gravitational wave sources with isolated field binary progenitors

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A significantly off-centre 56Ni distribution for the low-luminosity type Ia supernova SN 2016brx from the 100IAS survey★

component ejecta, with a power-law velocity distribution between

Nonthermal emission from clusters of galaxies

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The Progenitors of Type Ia Supernova Explosions are Head-On Collisions of White Dwarfs in Triple Systems

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An exact integral relation between the Ni56 mass and the bolometric light curve of a type Ia supernova

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Preliminary Evidence for a Virial Shock around the Coma Galaxy Cluster

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