Pulsar braking indices, glitches and energy dissipation in neutron stars

Alpar, M. A.; Baykal, A.

doi:10.1111/j.1365-2966.2006.10893.x

Cited by 60 publications

(62 citation statements)

References 40 publications

(121 reference statements)

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“…Finally, measurements of very large values of braking indices (Johnston and Galloway 1999) could be an indication of the closeness toḟ = 0 state associated with back bending. However, this might be explained in a more standard way, by the behavior connected with the glitch phenomena (Johnston and Galloway 1999;Alpar and Baykal 2006).…”

Section: Discussionmentioning

confidence: 97%

Equation of state of neutron star cores and spin down of isolated pulsars

Haensel

Zdunik

2007

Astrophys Space Sci

114

191

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We study possible impact of a softening of the equation of state by a phase transition, or appearance of hyperons, on the spin evolution of isolated pulsars. Numerical simulations are performed using exact 2-D simulations in general relativity. The equation of state of dense matter at supranuclear densities is poorly known. Therefore, the accent is put on the general correlations between evolution and equation of state, and mathematical strictness. General conjectures referring to the structure of the one-parameter families of stationary configurations are formulated. The interplay of the back bending phenomenon and stability with respect to axisymmetric perturbations is described. Changes of pulsar parameters in a corequake following instability are discussed, for a broad choice of phase transitions predicted by different theories of dense matter. The energy release in a corequake, at a given initial pressure, is shown to be independent of the angular momentum of collapsing configuration. This result holds for various types of phases transition, with and without metastability. We critically review observations of pulsars that could be relevant for the detection of the signatures of the phase transition in neutron star cores.

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Section: Discussionmentioning

confidence: 97%

Equation of state of neutron star cores and spin down of isolated pulsars

Haensel

Zdunik

2007

Astrophys Space Sci

114

191

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“…As discussed by Woods et al (2004), the negative sign of the fractional change of the pulse‐frequency derivative is unusual for large radio pulsar glitches. For large glitches, the fractional frequency change is Δν/ν > 10 −7 and the fractional pulse‐frequency derivative has the range (see also Alpar & Baykal 1994, 2006).…”

Section: Discussionmentioning

confidence: 99%

RXTE timing analysis of the anomalous X-ray pulsar 1E 2259+586

Icdem

Baykal

İnam

2011

Monthly Notices of the Royal Astronomical Society

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We present a pulse‐timing analysis of Rossi X‐ray Timing Explorer (RXTE) observations of the anomalous X‐ray pulsar 1E 2259+586 from its 2002 outburst to 2010 October. We have the following objectives: to extend the work on the recovery stage after the 2002 glitch; to investigate the variations caused by the second glitch that occurred in 2007; to look for other unusual events, if any, that arise in the regular spin‐down trend of the source. We find that the fractional change in the spin frequency derivative after the 2002 glitch is not stable as it decreased by an order of magnitude, from −2.2 × 10−2 to −1.278(3) × 10−3, in about 2.5 yr. Using a pulse‐timing analysis, we discover two small frequency shifts with fractional changes Δν/ν= 3.08(32) × 10−8 and Δν/ν=−1.39(11) × 10−8. While the first of these shifts is not found to have a fractional frequency derivative change, the second has . We interpret these frequency changes as positive and negative microglitches, similar to those seen in radio pulsars.

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“…In general the effects can be due to various processes including precession [128,129], Tkachenko modes [130], superfluid vortex creep [25], superfluid turbulence [103], or changes in the magnetic field [101,110,131]. Timing noise is of interest for the current discussion as it has been suggested that glitches below the observational threshold may be the cause of timing noise [25,132] and of the measurement of anomalous breaking indices [133,134]. Janessen & Stappers [135] in fact showed that small glitches can account for part of the timing noise in PSR B1951+32, but not all of it, while Hobbs et al [131] claimed that for young pulsars with τ c < 10…”

Section: Timing Noisementioning

confidence: 99%

Models of pulsar glitches

Haskell

Melatos

2015

Int. J. Mod. Phys. D

324

304

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Radio pulsars provide us with some of the most stable clocks in the universe. Nevertheless several pulsars exhibit sudden spin-up events, known as glitches. More than forty years after their first discovery, the exact origin of these phenomena is still open to debate. It is generally thought that they an observational manifestation of a superfluid component in the stellar interior and provide an insight into the dynamics of matter at extreme densities. In recent years there have been several advances on both the theoretical and observational side, that have provided significant steps forward in our understanding of neutron star interior dynamics and possible glitch mechanisms. In this article we review the main glitch models that have been proposed and discuss our understanding, in the light of current observations.Radio pulsars are thought to be rotating magnetised neutron stars (NS). The huge moment of inertia (of the order of 10 45 g cm 2 ) leads to exceptionally stable rotation rates and provides us with some of the most precise clocks in the universe. The best timed millisecond pulsars are stable to a precision which rivals that of atomic clocks [1]. Nevertheless radio pulsars exhibit several timing irregularities, the most striking of which are the so-called glitches. While most objects are observed to steadily spin-down due to the emission of electromagnetic and, possibly, gravitational waves, many pulsars show sudden increases in their spin, in some cases followed by an increase in their spin-down rate, i.e. glitches. Most pulsars also show slower, long-term, stochastic deviations from a regular spin-down law, that are generally classed as 'timing noise' and are not the main focus of this review article.Soon after the discovery of the first glitches in the Vela [2,3] and Crab [4,5] pulsars in 1969, several mechanisms were suggested to explain these phenomena. Although some initial suggestions featured external mechanisms, such as plasma explosions in the magnetosphere [6] or planets around the pulsar [7], the lack of radiative and pulse profile changes associated with these events was taken as evidence for an internal origin. The situation is different for rotating radio transients (RRATs) and magnetars, which are now known to glitch and do exhibit, amongst other peculiar traits, radiative changes associated with these events [8][9][10][11]. Magnetospheric activity is likely to play a role in these objects, as we discuss below.There are two main internal glitch mechanisms that have been examined in the literature. The first set of models relies on the fact that the outer layers of a neutron star form a crystalline crust that can support stress. As the NS spins down, the liquid core adjusts its shape to the rotation rate, while the solid crust maintains the shape appropriate for the previous, higher, spin rate. This leads to an increasing amount of strain building up in the crust, which is eventually released in the form of a star quake. The quake causes a sudden rearrangement of the moment of inertia and...

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Pulsar braking indices, glitches and energy dissipation in neutron stars

Cited by 60 publications

References 40 publications

Equation of state of neutron star cores and spin down of isolated pulsars

Equation of state of neutron star cores and spin down of isolated pulsars

RXTE timing analysis of the anomalous X-ray pulsar 1E 2259+586

Models of pulsar glitches

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