Search Publications

Cosmological Constraints from the Hubble Diagram of Quasars at High Redshifts

Lusso, E.; Risaliti, G.

The concordance model (Λ cold dark matter (ΛCDM) model, where Λ is the cosmological constant) reproduces the main current cosmological observations^1-4 assuming the validity of general relativity at all scales and epochs and the presence of CDM and of Λ, equivalent to dark energy with a constant density in space and time. However, the ΛC…

Anisotropic winds in a Wolf-Rayet binary identify a potential gamma-ray burst progenitor

Callingham, J. R.; Crowther, P. A.; Tuthill, P. G. +5 more

The massive evolved Wolf-Rayet stars sometimes occur in colliding-wind binary systems in which dust plumes are formed as a result of the collision of stellar winds¹. These structures are known to encode the parameters of the binary orbit and winds^2-4. Here we report observations of a previously undiscovered Wolf-Rayet system,…

The brightening of the pulsar wind nebula of PSR B0540-69 after its spin-down-rate transition

Wang, Q. D.; Zhang, S. N.; Ge, M. Y. +6 more

It is believed that an isolated pulsar loses its rotational energy mainly through a relativistic wind consisting of electrons, positrons and possibly Poynting flux^1-3. As it expands, this wind may eventually be terminated by a shock, where particles can be accelerated to energies of X-ray synchrotron emission, and a pulsar wind nebula (…

Observations of a pre-merger shock in colliding clusters of galaxies

Gu, Liyi; Mao, Junjie; Kaastra, Jelle S. +10 more

Clusters of galaxies are the largest known gravitationally bound structures in the Universe. When clusters collide, they create merger shocks on cosmological scales, which transform most of the kinetic energy carried by the cluster gaseous halos into heat^1-3. Observations of merger shocks provide key information on the merger dynamics, …