Pulsars observations

Abstract From the earliest measurements of the masses of binary pulsars, observations of neutron stars have placed interesting constraints on the properties of high-density matter. The last few years have seen a number of observational developments that could place strong new restrictions on the equilibrium state of cold matter at supranuclear densities. We review these astronomical constraints and their context, and speculate on future prospects. 

E. de Ona-Wilhelmi, The Optimization of the MAGIC Telescope for Pulsar Observations, PhD Thesis, Universidad Complutense de Madrid, 2004. 

M. Ryle and A, Hewish (Cambridge) pioneering research in radioastrophysics Ryle for his observations and inventions, in particular of the aperture-synthesis technique, and Hewish for his decisive role in the discovery of pulsars. 

This represents an upper limit for the dimensions of the nucleus. Compared with the estimates for the size of the atom, obtained from kinetic theory calculations on gases, which are typically 4x10 9 m. we can see that the nucleus is very small indeed compared to the atom as a whole - a radius ratio of 10-5, or a volume ratio of 10 15, which supports Rutherford s observation that most of an atom consists of empty space. We can also conclude that the density of the nucleus must be extremely high - 1015 times that encountered in ordinary matter, consistent with density estimates in astronomical objects called pulsars or neutron stars. 

In section I we consider the dynamics of rotation of a two-component neutron star and obtain the relaxation solutions for spin-down rate of the star. In section II we compare our solutions for the relaxation process with the observation data from the Vela pulsar. 

Alpar, A. (2003), Accretion models for young neutron stars , in Pulsars, AXPs and SGRs observed with BeppoSAX and other observatories . Edited by G. Cusumano, E. Massaro, T. Mineo. p. 197 [astro-ph/0306179]. 

Brisken, W.F. Fruchter, A.S. Goss, W.M., Hermstein, R.S. Thorsett, S.E. (2003), Proper-motion measurements with the VLA. II. Observations of twenty-eight pulsars, astro-ph/0309215. 

Gavriil, F.P., Kaspi, V.M., Woods, P.M. (2003), Anomalous X-ray pulsars long-term monitoring and soft-gamma repeater like X-ray bursts , in Pulsars, AXPs and SGRs observed with... 

The relation of the radius and the expected strength of the magnetic field is listed by the use of the hypothesis in Table. 1. Then, it looks to work well for explaining the strength of the magnetic field observed for radio pulsars. However, it does not work for magnetars considering the Schwarzschild radius,... 

The high-density phases of QCD at low temperatures can be realized in rotating compact stars - pulsars. Therefore, the observational data from pulsars could provide potentially important information on the state of matter at super-nuclear densities, in particular the superconducting quark matter. 

Neutron and quark stars are natural laboratories to investigate the interplay of strong, electro-weak and gravitational interaction. Many theoretically determined properties of these astrophysical objects were tested by the observed properties of pulsars, and detailed calculations exist for these stars[ 1 —4. ... 

Besides the above Crab-like SNRs with PSRs, ther are some Crab-like SNRs with central compact sources but no pulsating radiation being observed, such as 3C 58, G 21.5 -0.9, Kes 73 and Kes 75 et al.. If we assume that such compact sources are also pulsars in nature but only hidden and Eq(l) is approximately satisfied for them, their periods... 

The Conference was opened with a progress report on pulsars by Pacini, followed by speeches on the observational results on compact galactic X-ray sources by Giacconi, on the optical properties of binary X-ray sources by the Bahcalls, and a review on the physics of binary X-ray sources by Martin Rees. 

Neutron stars have also provided the first direct evidence of planets outside the solar system. The pulsar PSR 1257+12 rotates 161 times per second-but its pulses are not evenly spaced, as are the ones from the Crab. Observations made with the giant Arecibo radio telescope showed that some pulses arrive slightly too soon, others just a bit too late. This means something is tugging the pulsar back and forth slightly. Careful measurements showed that a pair of planets is responsible. 

If one uses the cosmic ray energy requirements and the nonthermal radiation as a guideline, then the most powerful accelerators of relativistic particles in the Galaxy should be supernovae and supernova remnants, pulsars, neutron stars in close binary systems, and winds of young massive stars. The total power Lcr needed to maintain the observed energy density of cosmic rays is estimated as 1041 erg/s. For the acceleration by a supernovae, this estimate... 

Pulsars. Since their discovery pulsars have been observed in a wide range of wavelengths. Several theoretical models of emission have been developed to explain these data. The EGRET detector of the CGRO satellite measured... 

Figure 3. Observation times ranges for Crab and PSR1951+32. K is the flux at lGeV and Eo is the spectral cutoff. The star corresponds to the pulsar position.

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