Predicting Ranges for Pulsars' Braking Indices

Magalhães, Nadja S.; Miranda, Thaysa A.; Frajuca, Carlos

doi:10.1088/0004-637x/755/1/54

Cited by 44 publications

(43 citation statements)

References 24 publications

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“…Several interpretations for the observed braking indices have been put forward, like the ones that propose either accretion of fall-back material via a circumstellar disk [10], relativistic particle winds [11,12], or modified canonical models to explain the observed braking index ranges (see e.g., [13][14][15], and references therein for further models). Alternatively, it has been proposed that the so-called quantum vacuum friction (QVF) effect in pulsars can explain several aspects of their phenomenology [16].…”

Section: Introductionmentioning

confidence: 99%

Gravitational waves from pulsars with measured braking index

2016

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We study the putative emission of gravitational waves (GWs) in particular for pulsars with measured braking index. We show that the appropriate combination of both GW emission and magnetic dipole brakes can naturally explain the measured braking index, when the surface magnetic field and the angle between the magnetic dipole and rotation axes are time dependent. Then we discuss the detectability of these very pulsars by aLIGO and the Einstein Telescope. We call attention to the realistic possibility that aLIGO can detect the GWs generated by at least some of these pulsars, such as Vela, for example.

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Section: Introductionmentioning

confidence: 99%

Gravitational waves from pulsars with measured braking index

2016

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“…Although data on many pulsars are available in the literature, there are only eight pulsars generally accepted to yield reliable data on the pulsar's spin-down (see Table. I, recent compilation [7] and Refs.…”

Section: Introductionmentioning

confidence: 99%

“…There have been many attempts to extend/modify the basics of the MDR model. These include consideration of magnetic field activity (e.g., [13,[18][19][20][21][22][23]), superfluidity and superconductivity of the matter within pulsars (e.g., [24][25][26]), and modifications of the power law and related quantities (e.g., [7,27]). Time dependence of the constants in the MDR model has also been considered [18,[28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Braking index of isolated pulsars

et al. 2015

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Isolated pulsars are rotating neutron stars with accurately measured angular velocities Ω, and their time derivatives that show unambiguously that the pulsars are slowing down. Although the exact mechanism of the spin-down is a question of detailed debate, the commonly accepted view is that it arises through emission of magnetic dipole radiation (MDR) from a rotating magnetized body. Other processes, including the emission of gravitational radiation, and of relativistic particles (pulsar wind), are also being considered. The calculated energy loss by a rotating pulsar with a constant moment of inertia is assumed proportional to a model dependent power of Ω. This relation leads to the power lawΩ = -K Ω n where n is called the braking index. The MDR model predicts n exactly equal to 3. Selected observations of isolated pulsars provide rather precise values of n, individually accurate to a few percent or better, in the range 1< n < 2.8, which is consistently less than the predictions of the MDR model. In spite of an extensive investigation of various modifications of the MDR model, no satisfactory explanation of observation has been found yet.The aim of this work is to determine the deviation of the value of n from the canonical n = 3 for a star with a frequency dependent moment of inertia in the region of frequencies from zero (static Our results show conclusively that, within the model used in this work, any significant deviation of the braking index away from the value n = 3 occurs at frequencies higher than about ten times 2 the frequency of the slow rotating isolated pulsars most accurately measured to date. The rate of change of n with frequency is related to the softness of the EoS and the M B of the star as this controls the degree of departure from sphericity. Change in the moment of inertia in the MDR model alone, even with the more realistic features considered here, cannot explain the observational data on the braking index and other mechanisms have to be sought.

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“…Yue et al 2007). By contrast, the few direct measurements of braking indices presently available lie in the range of 0.9-2.8 (for a compilation see Magalhaes et al 2012), indicating a much faster spin-down decay. In this study, we set it to the canonical n = 3.…”

Section: A6 Results Of the Time-dependent Modellingmentioning

confidence: 97%

A Population of TeV Pulsar Wind Nebulae in the H.E.S.S. Galactic Plane Survey

Klepser¹

2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

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The nine-year H.E.S.S. Galactic Plane Survey (HGPS) has yielded the most uniform observation scan of the inner Milky Way in the TeV gamma-ray band to date. The sky maps and source catalogue of the HGPS allow for a systematic study of the population of TeV pulsar wind nebulae found throughout the last decade. To investigate the nature and evolution of pulsar wind nebulae, for the first time we also present several upper limits for regions around pulsars without a detected TeV wind nebula. Our data exhibit a correlation of TeV surface brightness with pulsar spin-down powerĖ. This seems to be caused both by an increase of extension with decreasingĖ, and hence with time, compatible with a power law RPWN(Ė) ∼Ė −0.65±0.20 , and by a mild decrease of TeV gamma-ray luminosity with decreasingĖ, compatible with L1−10 TeV ∼Ė 0.59±0.21 . We also find that the offsets of pulsars with respect to the wind nebula centre with ages around 10 kyr are frequently larger than can be plausibly explained by pulsar proper motion and could be due to an asymmetric environment. In the present data, it seems that a large pulsar offset is correlated with a high apparent TeV efficiency L1−10 TeV /Ė. In addition to 14 HGPS sources considered firmly identified pulsar wind nebulae and 5 additional pulsar wind nebulae taken from literature, we find 10 HGPS sources that are likely TeV pulsar wind nebula candidates. Using a model that subsumes the present common understanding of the very high-energy radiative evolution of pulsar wind nebulae, we find that the trends and variations of the TeV observables and limits can be reproduced to a good level, drawing a consistent picture of present-day TeV data and theory.

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Predicting Ranges for Pulsars' Braking Indices

Cited by 44 publications

References 24 publications

Gravitational waves from pulsars with measured braking index

Gravitational waves from pulsars with measured braking index

Braking index of isolated pulsars

A Population of TeV Pulsar Wind Nebulae in the H.E.S.S. Galactic Plane Survey

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