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Modeling Phase-resolved Observations of the Surfaces of Magnetic Neutron Stars
Wynn C. G. Ho, Kaya Mori
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…
Constraining the Geometry of the Neutron Star RX J1856.5-3754
Wynn C. G. Ho
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…
Magnetic Hydrogen Atmosphere Models and the Neutron Star RX J1856.5-3754
Wynn C. G. Ho, David L. Kaplan, Philip Chang +2
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 satis…
Electromagnetic polarization in partially ionized plasmas with strong magnetic fields and neutron star atmosphere models
A. Y. Potekhin, Dong Lai, G. Chabrier +1
Polarizability tensor of a strongly magnetized plasma and the polarization vectors and opacities of normal electromagnetic waves are studied for the conditions typical of neutron s…
Spectral Features in the Thermal Emission from Isolated Neutron Stars: Dependence on Magnetic Field Strengths
Wynn C. G. Ho, Dong Lai
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 v…
Atmospheres and Spectra of Strongly Magnetized Neutron Stars -- III. Partially Ionized Hydrogen Models
Wynn C. G. Ho, Dong Lai, Alexander Y. Potekhin +1
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 temperatu…
Polarized X-Ray Emission from Magnetized Neutron Stars: Signature of Strong-Field Vacuum Polarization
Dong Lai, Wynn C. G. Ho
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 (depen…
Matter and Radiation in Superstrong Magnetic Fields and Thermal Emission from Neutron Stars
Dong Lai, W. C. G. Ho
Thermal surface emissions have now been detected from more than a dozen isolated neutron stars, including radio pulsars, radio-quiet neutron stars and magnetars. These detections c…
Atmospheres of Magnetized Neutron Stars: Vacuum Polarization and Partially Ionized Models
Wynn C. G. Ho, Dong Lai, Alexander Y. Potekhin +1
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…
Transfer of Polarized Radiation in Strongly Magnetized Plasmas and Thermal Emission from Magnetars: Effect of Vacuum Polarization
Dong Lai, W. C. G. Ho
We present a theoretical study of radiative transfer in strongly magnetized electron-ion plasmas, focusing on the effect of vacuum polarization due to quantum electrodynamics. This…
Comment on ``The Effect of Vacuum Polarization ... in Strongly Magnetized Plasmas'' by Ozel (astro-ph/0203449)
Dong Lai, Wynn C. G. Ho
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…
Atmospheres and Spectra of Strongly Magnetized Neutron Stars II: Effect of Vacuum Polarization
Wynn C. G. Ho, Dong Lai
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 magne…
BVRI Photometry of Supernovae
Wynn C. G. Ho, Schuyler D. Van Dyk, Chien Y. Peng +5
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 1…
Resonant Conversion of Photon Modes Due to Vacuum Polarization in a Magnetized Plasma: Implications for X-Ray Emission from Magnetars
Dong Lai, Wynn C. G. Ho
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…
A Search for Rapid Photometric Variability in Symbiotic Binaries
J. L. Sokoloski, Lars Bildsten, Wynn C. G. Ho
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 accret…
Atmospheres and Spectra of Strongly Magnetized Neutron Stars
Wynn C. G. Ho, Dong Lai
We construct atmosphere models for strongly magnetized neutron stars with surface fields G and effective temperatures K. The atm…
R-Mode Oscillations and Spindown of Young Rotating Magnetic Neutron Stars
Wynn C. G. Ho, Dong Lai
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 evoluti…
Resonant Tidal Excitations of Rotating Neutron Stars in Coalescing Binaries
Wynn C. G. Ho, Dong Lai
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…