We construct models for strongly-magnetized neutron star atmospheres composed of mid-Z elements (carbon, oxygen and neon) with magnetic fields B = 1012–1013 G and effective temperatures Teff = (1 − 5) × 106 K; this is done by first addressing the physics relevant to strongly-magnetized plasmas and calculating the equation of state and polarizationdependent opacities. We then obtain the atmosphe...

Neutron interactions with matter can be either scattering or absorption reactions. Scattering can result in a change in the energy and direction of motion of a neutron but cannot directly cause the disappearance of a free neutron. Absorption leads to the disappearance of free neutrons as a result of a nuclear reaction with fission or the formation of a new nucleus and another particle or partic...

We report on the results of a deep XMM-Newton observation of RBS 1774, the most recent dim isolated neutron star candidate found in the ROSAT archive data. Spectral and timing analysis of the high-quality PN and MOS data confirm the association of this source with an isolated neutron star. The spectrum is thermal and blackbody-like, and there is evidence at a significance level > 4σ that the so...

In proto-neutron stars with strong magnetic fields, the cross section for νe (ν̄e) absorption on neutrons (protons) depends on the local magnetic field strength due to the quantization of energy levels for the e (e+) produced in the final state. If the neutron star possesses an asymmetric magnetic field topology in the sense that the magnitude of magnetic field in the north pole is different fro...

In proto-neutron stars with strong magnetic fields, the cross section for νe (ν̄e) absorption on neutrons (protons) depends on the local magnetic field strength due to the quantization of energy levels for the e (e+) produced in the final state. If the neutron star possesses an asymmetric magnetic field topology in the sense that the magnitude of magnetic field in the north pole is different fro...

Aims. By measuring the gravitational redshift of spectral features in the spectrum of thermal radiation emitted from neutron stars, useful constraints for the equation of state of superdense matter can be obtained via an estimate of the mass-to-radius ratio. We searched for spectral line features in the high-resolution X-ray spectrum of the isolated neutron star RX J0720.4−3125. Methods. Our ta...

We report spectral and variability analysis of two quiescent low mass X-ray binaries (X5 and X7, previously detected with the ROSAT HRI) in a Chandra ACIS-I observation of the globular cluster 47 Tuc. X5 demonstrates sharp eclipses with an 8.666±0.01 hr period, as well as dips showing an increased NH column. The thermal spectra of X5 and X7 are well-modeled by unmagnetized hydrogen atmospheres ...

A method is described for measuring the concentration of calcium in arterial tissue by neutron activation analysis. The principal advantage is that the method is nondestructive and is ideal for analytical situations in which multiple biochemical measurements are required on a few-milligram sample. Application of the method is illustrated here by a study of aortic calcium metabolism in pigeons a...

We examine properties of thermal radiation emitted by strongly magnetized neutron stars (NSs). In particular, we show that the pulsation amplitudes of the energy-integrated flux are an increasing function of the absorption column density to the source. This is especially important for the interpretation of the Anomalous X-ray Pulsars (AXPs) as cooling neutron stars with high magnetic fields. We...

Presently seven nearby radio-quiet isolated neutron stars discovered in ROSAT data and characterized by thermal X-ray spectra are known. They exhibit very similar properties and despite intensive searches their number remained constant since 2001 which led to their name “The Magnificent Seven”. Five of the stars exhibit pulsations in their X-ray flux with periods in the range of 3.4 s to 11.4 s...