Related papers: Pulsars and quark stars
A growing number of early Be stars discovered in X-ray surveys exhibit X-ray luminosities intermediate between those of normal stars and those of most Be/X-ray binaries in quiescence. Their X-ray spectra are also much harder than those of…
In this brief review I summarize our basic knowledge about different types of isolated neutron stars. I discuss radio pulsars, central compact objects in supernova remnants, magnetars, near-by cooling neutron stars (aka the Magnificent…
Observations of cooling neutron stars allow to measure photospheric radii and to constrain the equation of state of nuclear matter at high densities. In this paper we concentrate on neutron stars, which show thermal (photospheric) X-ray…
The relationship between pulsar-like compact stars and gravitational waves is briefly reviewed. Due to regular spins, pulsars could be useful tools for us to detect ~nano-Hz low-frequency gravitational waves by pulsar-timing array…
Nuclear-powered X-ray millisecond pulsars are the third type of millisecond pulsars, which are powered by thermonuclear fusion processes. The corresponding brightness oscillations, known as burst oscillations, are observed during some…
The true ground state of hadronic matter may be strange quark matter (SQM). Consequently, the observed pulsars may actually be strange quark stars, but not neutron stars. However, proving or disproving the SQM hypothesis still remains to be…
Millisecond pulsars are neutron stars (NSs) that are thought to have been spun-up by mass accretion from a stellar companion. It is unknown whether there is a natural brake for this process, or if it continues until the centrifugal breakup…
Strange quark matter (SQM) may be the true ground state of matter. According to this SQM hypothesis, the observed neutron stars actually should all be strange quark stars. But distinguishing between neutron stars and strange quark stars by…
Millisecond pulsars are rapidly rotating neutron stars where general relativity plays a strong role in the propagation of light from the neutron star to observer. The observed X-ray pulse shapes carry information on the mass, radius and…
The origin of high-redshift quasars and their supermassive black hole engines is unclear. One promising solution is the collapse of a primordial supermassive star. Observational confirmation of this scenario may be challenging, but a…
Observations obtained in the last years challenged the widespread notion that rotation-powered neutron stars are steady X-ray emitters. Besides a few allegedly rotation-powered neutron stars that showed "magnetar-like" variability, a…
Rotation-powered "recycled" millisecond pulsars are a variety of rapidly-spinning neutron stars that typically show thermal X-ray radiation due to the heated surface of their magnetic polar caps. Detailed numerical modeling of the…
X-ray pulsars (XRPs) consist of a magnetized neutron star (NS) and an optical donor star. The NS accretes matter from the donor star producing pulsed X-ray emission. In most cases the donor stars are Be stars, and accretion is episodic,…
Anomalous X-ray pulsars (AXPs) are slowly rotating neutron stars with very bright and highly variable X-ray emission that are believed to be powered by ultra-strong magnetic fields of >1e14 G, according to the 'magnetar' model. The radio…
Pulsar glitches are thought to be probes of the superfluid interior of neutron stars. These sudden jumps in frequency observed in many pulsars are generally assumed to be the macroscopic manifestation of superfluid vortex motion on a…
Neutron stars are rich laboratories of multiple branches of modern physics. These include gravitational physics, nuclear and particle physics, (quantum) electrodynamics, and plasma astrophysics. In this chapter, we present the pioneering…
TThe glitch of anomalous X-ray pulsars \& soft gamma repeaters (AXP/SGRs) usually accompanied with detectable energy releases manifesting as X-ray bursts or outbursts, while the glitch of some pulsars like Vela release negligible energy. We…
The detection, in 1998, of the first Accreting Millisecond Pulsar, started an exciting season of continuing discoveries in the fashinating field of compact binary systems harbouring a neutron star. Indeed, in these last three lustres,…
It has been recently suggested that magnetically affected neutrino oscillations inside a cooling protoneutron star, created in a supernova explosion, could explain the large proper motion of pulsars. We investigate whether this hypothesis…
Magnetars are the strongest magnets in the present universe and the combination of extreme magnetic field, gravity and density makes them unique laboratories to probe current physical theories (from quantum electrodynamics to general…