Related papers: Magnetized Atmospheres around Accreting Neutron St…
We present a detailed investigation of neutron star atmospheres with low magnetic fields, $B < 10^8 -10^{10}$ G, which do not affect opacities and equation of state of the atmospheric matter. We compute the atmospheric structure, emergent…
The spectral properties of X--ray radiation produced in a static atmosphere around a neutron star accreting at very low rates are investigated. Previous results by Alme \& Wilson (1973) are extended to the range $10^{-7}\leq L/L_{Edd}\leq…
The structure of static atmospheres around unmagnetized neutron stars undergoing steady, spherical accretion is discussed. We focus on the ``hot'' configurations presented by Turolla et al. (1994) and calculate the radiation spectrum using…
Recent observations of X-ray pulsars at low luminosities allow, for the first time, to compare theoretical models for the emission from highly magnetized neutron star atmospheres at low mass accretion rates ($\dot{M} \lesssim 10^{15}$ g…
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 determine the characteristics of thermal…
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 full radiative transfer equations for…
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 few \times 10^5-10^6 K. These models are…
Observed X-ray spectra of some isolated magnetized neutron stars display absorption features, sometimes interpreted as ion cyclotron lines. Modeling the observed spectra is necessary to check this hypothesis and to evaluate neutron star…
We present a new computer code for modeling magnetized neutron star atmospheres in a wide range of magnetic fields (10^{12} - 10^{15} G) and effective temperatures (3 \times 10^5 - 10^7 K). The atmosphere is assumed to consist either of…
Some thermonuclear (type I) X-ray bursts at the neutron star surfaces in low-mass X-ray binaries take place during hard persistent states of the systems. Spectral evolution of these bursts is well described by the atmosphere model of a…
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 Teff=(1-5)*10^6 K; this is done by first…
Recently Sanwal et al. (2002) reported the first clear detection of absorption features in an isolated neutron star, 1E1207.4-5209. Remarkably their spectral modeling demonstrates that the atmosphere cannot be Hydrogen. They speculated that…
We present a comprehensive investigation of the two broad absorption features observed in the X-ray spectrum of the neutron star 1E1207.4-5209 based on a recent analysis of the 260 ksec XMM-Newton data by Mori et al. 2005. Expanding on our…
Thermal surface radiation has been detected with X-ray instruments for several neutron stars with high spectral, spatial and timing resolution. These observations allow for direct study of fundamental properties of the source, but require…
We present an equation of state and radiative opacities for a strongly magnetized hydrogen plasma at magnetic fields B, temperatures T, and densities \rho typical for atmospheres of isolated neutron stars. The first- and second-order…
We investigate the atmosphere, ocean, and crust of neutron stars accreting at rates sufficiently high (typically in excess of the local Eddington limit) to stabilize the burning of accreted hydrogen and helium. For hydrogen-rich accretion…
Using a Hartree-Fock formalism, we estimate energy levels and photon cross sections for atomic iron in magnetic fields B ~ 10^13 G. Computing ionization equilibrium and normal mode opacities with these data, we construct LTE neutron star…
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 logT_eff=5.5-6.8, as well as with surface B…
We present an extended set of model atmospheres and emergent spectra of X-ray bursting neutron stars in low mass X-ray binaries. Compton scattering is taken into account. The models were computed in LTE approximation for six different…
Strong magnetic field of accreting neutron stars ($10^{14}$ G) is hard to probe by X-ray spectroscopy but can be indirectly inferred from spin-up/spin-down measurement in X-ray pulsars. The existing observations of slowly rotating X-ray…