Browsing by Author "Ho, Wynn C. G."

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    Pinning down the superfluid and measuring masses using pulsar glitches
    (2015) Ho, Wynn C. G.; Espinoza, Cristobal M.; Antonopoulou, Danai; Andersson, Nils
    Pulsars are known for their superb timing precision, although glitches can interrupt the regular timing behavior when the stars are young. These glitches are thought to be caused by interactions between normal and superfluid matter in the crust of the star. However, glitching pulsars such as Vela have been shown to require a superfluid reservoir that greatly exceeds that available in the crust. We examine a model in which glitches tap the superfluid in the core. We test a variety of theoretical superfluid models against the most recent glitch data and find that only one model can successfully explain up to 45 years of observational data. We develop a new technique for combining radio and x-ray data to measure pulsar masses, thereby demonstrating how current and future telescopes can probe fundamental physics such as superfluidity near nuclear saturation.
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    Prospects for Time-Domain and Multi-Messenger Science with AXIS
    (2024) Arcodia, Riccardo; Bauer, Franz E.; Cenko, S. Bradley; Dage, Kristen C.; Haggard, Daryl; Ho, Wynn C. G.; Kara, Erin; Koss, Michael; Liu, Tingting; Mallick, Labani; Negro, Michela; Pradhan, Pragati; Quirola-Vasquez, J.; Reynolds, Mark T.; Ricci, Claudio; Rothschild, Richard E.; Sridhar, Navin; Troja, Eleonora; Yao, Yuhan
    The Advanced X-ray Imaging Satellite (AXIS) promises revolutionary science in the X-ray and multi-messenger time domain. AXIS will leverage excellent spatial resolution (<1.5 arcsec), sensitivity (80x that of Swift), and a large collecting area (5-10x that of Chandra) across a 24-arcmin diameter field of view at soft X-ray energies (0.3-10.0 keV) to discover and characterize a wide range of X-ray transients from supernova-shock breakouts to tidal disruption events to highly variable supermassive black holes. The observatory's ability to localize and monitor faint X-ray sources opens up new opportunities to hunt for counterparts to distant binary neutron star mergers, fast radio bursts, and exotic phenomena like fast X-ray transients. AXIS will offer a response time of <2 h to community alerts, enabling studies of gravitational wave sources, high-energy neutrino emitters, X-ray binaries, magnetars, and other targets of opportunity. This white paper highlights some of the discovery science that will be driven by AXIS in this burgeoning field of time domain and multi-messenger astrophysics. This White Paper is part of a series commissioned for the AXIS Probe Concept Mission; additional AXIS White Papers can be found at the AXIS website.