C G Bassa

Learn More
Cosmic rays are the most energetic particles arriving at Earth. Although most of them are thought to be accelerated by supernova remnants, the details of the acceleration process and its efficiency are not well determined. Here we show that the pressure induced by cosmic rays exceeds the thermal pressure behind the northeast shock of the supernova remnant(More)
Optical observations of the companions of pulsars can help determine the properties of the binaries, as well as those of their components , and give clues to the preceding evolution. In this review, we first describe the different classes of binary pulsars, and present a table with a summary what is known about their optical counterparts. Next, we focus on(More)
  • C G Bassa, M H Van Kerkwijk, D Koester, F Verbunt
  • 2006
We present spectroscopic and photometric observations of the optical counterpart to PSR J1911−5958A, a millisecond pulsar located towards the globular cluster NGC 6752. We measure radial velocities from the spectra and determine the systemic radial velocity of the binary and the radial-velocity amplitude of the white-dwarf orbit. Combined with the pulsar(More)
We present the identification of the optical counterparts to the low-mass X-ray binaries 1A 1246−588 and 4U 1812−12. We determine the X-ray position of 1A 1246−588 from ROSAT/PSPC observations and find within the error circle a blue star with V = 19.45, B − V = 0.22 and R − I = 0.22 which we identify as the counterpart. Within the Chandra error circle of 4U(More)
We analyse the stochastic properties of the 49 pulsars that comprise the first International Pulsar Timing Array (IPTA) data release. We use Bayesian methodology, performing model selection to determine the optimal description of the stochastic signals present in each pulsar. In addition to spin-noise and dispersion-measure (DM) variations, these models can(More)
Context. In August 2008, the accreting millisecond X-ray pulsar (AMXP), IGR J00291+5934, underwent an outburst lasting ∼ 100 days, the first since its discovery in 2004. Aims. We present data from the 2008 double-peaked outburst of IGR J00291+5934 from Faulkes Telescope North, the Isaac Newton Telescope, the Keck Telescope, PAIRITEL, the Westerbork(More)
The paucity of observed supermassive black hole binaries (SMBHBs) may imply that the gravitational wave background (GWB) from this population is anisotropic, rendering existing analyses suboptimal. We present the first constraints on the angular distribution of a nanohertz stochastic GWB from circular, inspiral-driven SMBHBs using the 2015 European Pulsar(More)
Pulsars with compact companions in close eccentric orbits are unique laboratories for testing general relativity and alternative theories of gravity. Moreover, they are excellent targets for future gravitational wave experiments like LISA and they are also highly important for understanding the equation of state of super-dense matter and the evolution of(More)
We present phase resolved optical spectroscopy and X-ray timing of the neutron star X-ray binary EXO 0748−676 after the source returned to quiescence in the fall of 2008. The X-ray light curve displays eclipses consistent in orbital period, orbital phase and duration with the predictions and measurements before the return to quiescence. Hα and He I emission(More)
We carried out X-ray and optical observations of 1RXS J171824.2–402934. A monitoring campaign with Chandra and Swift confirms that it is the persistently accreting low-mass X-ray binary with the lowest known mass accretion rate. The second thermonuclear X-ray flash ever was detected, with RXTE-ASM, testifies to the low accretion rate. Accretion disk theory(More)