J M Sarkissian

Learn More
On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass(More)
This manuscript is an updated version of Kalogera et al. (2004) published in ApJ Letters to correct our calculation of the Galactic DNS coalescence rate. The details of the original erratum submitted to ApJ Letters are given in page 6 of this manuscript. We report on the newly increased event rates due to the recent discovery of the highly relativistic(More)
Analysis of ten years of high-precision timing data on the millisecond pulsar PSR J0437−4715 has resulted in a model-independent kinematic distance based on an apparent orbital period derivative, ˙ P b , determined at the 1.5% level of precision (D k = 157.0±2.4 pc), making it one of the most accurate stellar distance estimates published to date. The(More)
Using a statistically rigorous analysis method, we place limits on the existence of an isotropic stochastic gravitational wave background using pulsar timing observations. We consider backgrounds whose characteristic strain spectra may be described as a power-law dependence with frequency. Such backgrounds include an astrophysical background produced by(More)
The merger of close binary systems containing two neutron stars should produce a burst of gravitational waves, as predicted by the theory of general relativity. A reliable estimate of the double-neutron-star merger rate in the Galaxy is crucial in order to predict whether current gravity wave detectors will be successful in detecting such bursts. Present(More)
The double pulsar system PSR J0737-3039A/B is unique in that both neutron stars are detectable as radio pulsars. They are also known to have much higher mean orbital velocities and accelerations than those of other binary pulsars. The system is therefore a good candidate for testing Einstein's theory of general relativity and alternative theories of gravity(More)
Binary pulsars provide an excellent system for testing general relativity because of their intrinsic rotational stability and the precision with which radio observations can be used to determine their orbital dynamics. Measurements of the rate of orbital decay of two pulsars have been shown to be consistent with the emission of gravitational waves as(More)
General relativity predicts that the spin axes of the pulsars in the double-pulsar system (PSR J0737−3039A/B) will precess rapidly, in general leading to a change in the observed pulse profiles. We have observed this system over a one-year interval using the Parkes 64-m radio telescope at three frequencies: 680, 1390 and 3030 MHz. These data, combined with(More)
Analysis of 20 months of observations at the Parkes radio telescope shows secular changes in the pulsed emission from J0737−3039B, the 2.77 s pulsar of the double-pulsar system. Pulse profiles are becoming single-peaked in both bright phases of the orbital modulation although there is no clear variation in overall pulse width. The shape of the orbital(More)
We present a novel experiment with the capacity to independently measure both the electron density and the magnetic field of the solar corona. We achieve this through measurement of the excess Faraday rotation due to propagation of the polarised emission from a number of pulsars through the magnetic field of the solar corona. This method yields independent(More)