A Neutron Star with a Carbon Atmosphere in the Cassiopeia A Supernova Remnant (2009)
Ho, Wynn C. G., Heinke, Craig O.
The surface of hot neutron stars is covered by a thin atmosphere. If there is accretion after neutron star formation, the atmosphere could be composed of light elements (H or He); if no accretion...
Polarized X-rays from Magnetized Neutron Stars (2009)
Lai, Dong, Ho, Wynn C. G., Van Adelsberg, Matthew, Wang, Chen, Heyl, Jeremy S.
We review the polarization properties of X-ray emission from highly magnetized neutron stars, focusing on emission from the stellar surfaces. We discuss how x-ray polarization can be used to...
Model X-ray Spectra of Magnetic Neutron Stars with Hydrogen Atmospheres (2008)
Ho, Wynn C. G., Potekhin, Alexander Y., Chabrier, Gilles
We construct partially ionized hydrogen atmosphere models for magnetized neutron stars in radiative equilibrium with fixed surface fields between B=10^12 and 2x10^13 G and effective temperatures...
Modeling Phase-resolved Observations of the Surfaces of Magnetic Neutron Stars (2007)
Recent observations by XMM-Newton detected rotational pulsations in the total brightness and spectrum of several neutron stars. To properly interpret the data, accurate modeling of neutron star...
Constraining the Geometry of the Neutron Star RX J1856.5-3754 (2007)
RX J1856.5-3754 is one of the brightest, nearby isolated neutron stars, and considerable observational resources have been devoted to its study. In previous work, we found that our latest models of a...
Magnetic Hydrogen Atmosphere Models and the Neutron Star RX J1856.5-3754 (2006)
Ho, Wynn C. G., Kaplan, David L., Chang, Philip, Van Adelsberg, Matthew, Potekhin, Alexander Y.
RX J1856.5-3754 is one of the brightest nearby isolated neutron stars, and considerable observational resources have been devoted to it. However, current models are unable to satisfactorily explain...
Modelling mid-Z element atmospheres for strongly-magnetized neutron stars (2006)
We construct models for strongly-magnetized neutron star atmospheres composed of mid-Z elements (carbon, oxygen and neon) with magnetic fields B=10^{12}-10^{13} G and effective temperatures...
We study several effects that influence the strength of the proton cyclotron and atomic features in the thermal spectra of magnetic neutron stars. We show that it is possible for vacuum polarization...
Ho, Wynn C. G., Lai, Dong, Potekhin, Alexander Y., Chabrier, Gilles
We construct partially ionized hydrogen atmosphere models for magnetized neutron stars in radiative equilibrium with surface fields B=10^12-5 \times 10^14 G and effective temperatures T_eff \sim a...
In the atmospheric plasma of a strongly magnetized neutron star, vacuum polarization can induce a Mikheyev-Smirnov-Wolfenstein like resonance across which a X-ray photon may (depending on its energy)...
Atmospheres of Magnetized Neutron Stars: Vacuum Polarization and Partially Ionized Models (2002)
Ho, Wynn C. G., Lai, Dong, Potekhin, Alexander Y., Chabrier, Gilles
We construct hydrogen atmosphere models for magnetized neutron stars in radiative equilibrium with surface fields B=10^12-5x10^14 G and effective temperatures T_eff a few x 10^5-10^6 K by solving the...
We have recently shown that in a highly magnetized neutron star atmospheric plasma, vacuum polarization can induce resonant conversion of photon polarization modes via a mechanism analogous to MSW...
We study the effect of vacuum polarization on the atmosphere structure and radiation spectra of neutron stars with surface magnetic fields B=10^14-10^15 G, as appropriate for magnetars. Vacuum...
BVRI Photometry of Supernovae (2001)
Ho, Wynn C. G., Van Dyk, Schuyler D., Peng, Chien Y., Filippenko, Alexei V., Leonard, Douglas C., Matheson, Thomas, ...
We present optical photometry of one Type IIn supernova (1994Y) and nine Type Ia supernovae (1993Y, 1993Z, 1993ae, 1994B, 1994C, 1994M, 1994Q, 1994ae, and 1995D). SN 1993Y and SN 1993Z appear to be...
It is known that vacuum polarization can modify the photon propagation modes in the atmospheric plasma of a strongly magnetized neutron star. A resonance occurs when the effect of vacuum polarization...
Atmospheres and Spectra of Strongly Magnetized Neutron Stars (2001)
We construct atmosphere models for strongly magnetized neutron stars with surface fields $B\sim 10^{12}-10^{15}$ G and effective temperatures $T_{\rm eff}\sim 10^6-10^7$ K. The atmospheres directly...
A Search for Rapid Photometric Variability in Symbiotic Binaries (2001)
Sokoloski, J. L., Bildsten, Lars, Ho, Wynn C. G.
We report on our survey for rapid (time scale of minutes) photometric variability in symbiotic binaries. These binaries are becoming an increasingly important place to study accretion onto white...
R-Mode Oscillations and Spindown of Young Rotating Magnetic Neutron Stars (1999)
Recent work has shown that a young, rapidly rotating neutron star loses angular momentum to gravitational waves generated by unstable r-mode oscillations. We study the spin evolution of a young,...
Resonant Tidal Excitations of Rotating Neutron Stars in Coalescing Binaries (1998)
In a coalescing neutron star-neutron star (NS-NS) or neutron star-black hole (NS-BH) binary, oscillation modes of the NS can be resonantly excited by the companion during the final minutes of the...