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Binary pulsar systems are superb probes of stellar and binary evolution and the physics of extreme environments. In a survey with the Arecibo telescope, we have found PSR J1903+0327, a radio pulsar with a rotational period of 2.15 milliseconds in a highly eccentric (e = 0.44) 95-day orbit around a solar mass (M(middle dot in circle)) companion. Infrared(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)
Many physically motivated extensions to general relativity (GR) predict substantial deviations in the properties of spacetime surrounding massive neutron stars. We report the measurement of a 2.01 ± 0.04 solar mass (M⊙) pulsar in a 2.46-hour orbit with a 0.172 ± 0.003 M⊙ white dwarf. The high pulsar mass and the compact orbit make this system a sensitive(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)
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)
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. ABSTRACT We report on the Chandra X-ray Observatory and Hubble Space(More)
We report on our analysis of a 20 ksec Chandra X–ray observation of the quasi– persistent neutron star soft X–ray transient (SXT) 1M 1716–315 in quiescence. Only one source was detected in the HEAO–I error region. Its luminosity is 1.6×10 32 − 1.3 × 10 33 erg s −1. In this the range is dominated by the uncertainty in the source distance. The source spectrum(More)
We present Chandra X-ray Observatory ACIS-S3 X-ray imaging observations and VLT/FORS2 and Hubble Space Telescope optical observations of two low-density Galactic globular clusters; NGC 6366 and M55. We detect 16 X-ray sources with 0.5-6.0keV lumi­ nosities above LX = 4 x 1030 erg s-1 within the half-mass radius of M55, of which 8 or 9 are expected to be(More)