Search Publications
Polarized x-rays constrain the disk-jet geometry in the black hole x-ray binary Cygnus X-1
Ingram, Adam; Wu, Kinwah; Enoto, Teruaki +111 more
A black hole x-ray binary (XRB) system forms when gas is stripped from a normal star and accretes onto a black hole, which heats the gas sufficiently to emit x-rays. We report a polarimetric observation of the XRB Cygnus X-1 using the Imaging X-ray Polarimetry Explorer. The electric field position angle aligns with the outflowing jet, indicating t…
A transient radio source consistent with a merger-triggered core collapse supernova
Kulkarni, S. R.; Hallinan, G.; Horesh, A. +10 more
A core collapse supernova occurs when exothermic fusion ceases in the core of a massive star, which is typically caused by exhaustion of nuclear fuel. Theory predicts that fusion could be interrupted earlier by merging of the star with a compact binary companion. We report a luminous radio transient, VT J121001+495647, found in the Very Large Arra…
A fast and long-lived outflow from the supermassive black hole in NGC 5548
Kaastra, J. S.; Harrison, F. A.; Nandra, K. +31 more
Supermassive black holes in the nuclei of active galaxies expel large amounts of matter through powerful winds of ionized gas. The archetypal active galaxy NGC 5548 has been studied for decades, and high-resolution x-ray and ultraviolet (UV) observations have previously shown a persistent ionized outflow. An observing campaign in 2013 with six spa…
Early 56Ni decay gamma rays from SN2014J suggest an unusual explosion
Diehl, Roland; Grebenev, Sergei A.; Greiner, Jochen +7 more
Type Ia supernovae result from binary systems that include a carbon-oxygen white dwarf, and these thermonuclear explosions typically produce 0.5 solar mass of radioactive 56Ni. The 56Ni is commonly believed to be buried deeply in the expanding supernova cloud. In SN2014J, we detected the lines at 158 and 812 kiloelectron volt…
Polarized Gamma-Ray Emission from the Galactic Black Hole Cygnus X-1
Rodriguez, J.; Wilms, J.; Laurent, P. +3 more
Because of their inherently high flux allowing the detection of clear signals, black hole x-ray binaries are interesting candidates for polarization studies, even if no polarization signals have been observed from them before. Such measurements would provide further detailed insight into these sources’ emission mechanisms. We measured the polariza…
Polarized Gamma-Ray Emission from the Crab
Hill, A. B.; Bird, A. J.; Ubertini, P. +7 more
Pulsar systems accelerate particles to immense energies. The detailed functioning of these engines is still poorly understood, but polarization measurements of high-energy radiation may allow us to locate where the particles are accelerated. We have detected polarized gamma rays from the vicinity of the Crab pulsar using data from the spectrometer…