A Model for the Challenging "Bi-drifting" Phenomenon in PSR J0815+09

Qiao, G. J.; Lee, K. J.; Zhang, Bing; Xu, R. X.; Wang, Hong Guang

doi:10.1086/426862

Cited by 54 publications

(37 citation statements)

References 22 publications

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“…This "bi-drifting" subpulse behavior is also observed for PSR J0815+09, which also has opposite drift senses in different components (McLaughlin et al 2004). This "bi-drifting" could be a sign that these pulsars have both an inner annular gap and an inner core gap (Qiao et al 2004), but also "double imaging" could be responsible . Note also that the second harmonic of the drift feature is visible in the 2DFS of especially the trailing component.…”

Section: Known Drifters (Class "Coh")mentioning

confidence: 99%

The subpulse modulation properties of pulsars at 21 cm

Weltevrede¹,

Edwards

Stappers

2005

A&A

218

453

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We present the results of a systematic, unbiased search for subpulse modulation of 187 pulsars performed with the Westerbork Synthesis Radio Telescope (WSRT) in the Netherlands at an observing wavelength of 21 cm. Using new observations and archival WSRT data we have increased the list of pulsars that show the drifting subpulse phenomenon by 42, indicating that at least one in three pulsars exhibits this phenomenon. The real fraction of pulsars that show the drifting phenomenon is likely to be larger than 55%. The majority of the analysed pulsars show subpulse modulation (170), of which the majority were not previously known to show subpulse modulation and 30 show clear systematic drifting. The large number of new drifters we have found allows us, for the first time, to do meaningful statistics on the drifting phenomenon. We find that the drifting phenomenon is correlated with the pulsar age such that drifting is more likely to occur in older pulsars. Pulsars that drift more coherently seem to be older and have a lower modulation index. There is no significant correlation found between P 3 and other pulsar parameters (such as the pulsar age), as has been reported in the past. There is no significant preference of drift direction and the drift direction is not found to be correlated with pulsar parameters. None of the four complexity parameters predicted by different emission models are shown to be inconsistent with the set of modulation indices of our sample of pulsars. Therefore none of the models can be ruled out based on our observations. We also present results on some interesting new individual sources like a pulsar that shows similar subpulse modulation in both the main-and interpulse and six pulsars with opposite drift senses in different components.

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Section: Known Drifters (Class "Coh")mentioning

confidence: 99%

The subpulse modulation properties of pulsars at 21 cm

Weltevrede¹,

Edwards

Stappers

2005

A&A

218

453

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“…The IAG is likely to require the star to be a bare strange star in order for it to develop. It was argued by Qiao et al (2004b) that a carousel of sparks could exist in both regions, each rotating in an opposite sense. This provides the physical basis for different components having opposite drift senses.…”

Section: Oppositely Circulating Nested Beamlet Systemsmentioning

confidence: 99%

“…What makes this pulsar highly unusual is that the drifting subpulses detected in the two components of the pulse profile appear to drift in opposite directions, a phenomenon dubbed bi-drifting by Qiao et al (2004b). Bi-drifting has only been observed for one other pulsar: PSR J0815+0939 (McLaughlin et al 2004;Champion et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Investigation of the bi-drifting subpulses of radio pulsar B1839−04 utilising the open-source data-analysis project PSRSALSA

Weltevrede

2016

A&A

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Aims. The usefulness and versatility of the PSRSALSA open-source pulsar data-analysis project is demonstrated through an analysis of the radio pulsar B1839−04. This study focuses on the phenomenon of bi-drifting, an effect where the drift direction of subpulses is systematically different in different pulse profile components. Bi-drifting is extremely rare in the pulsar population, and the theoretical implications are discussed after comparing B1839−04 with the only other known bi-drifter. Methods. Various tools in PSRSALSA, including those allowing quantification of periodicities in the subpulse modulation, their flux distribution, and polarization properties, are exploited to obtain a comprehensive picture of the radio properties of PSR B1839−04. In particular, the second harmonic in the fluctuation spectra of the subpulse modulation is exploited to convincingly demonstrate the existence of bi-drifting in B1839−04. Bi-drifting is confirmed with a completely independent method allowing the average modulation cycle to be determined. Polarization measurements were used to obtain a robust constraint on the magnetic inclination angle. Results. The angle between the rotation and magnetic axis is found to be smaller than 35 • . Two distinct emission modes are discovered to be operating, with periodic subpulse modulation being present only during the weaker mode. Despite the variability of the modulation cycle and interruption by mode-changes, the modulation pattern responsible for the bi-drifting is strictly phase locked over a timescale of years such that the variability is identical in the different components. Conclusions. The phase locking implies that a single physical origin is responsible for both drift directions. Phase locking is hard to explain for many models, including those specifically proposed in the literature to explain bi-drifting, and they are therefore shown to be implausible. It is argued that within the framework of circulating beamlets, bi-drifting could occur if the circulation were severely distorted, possibly by distortions in the magnetic field.

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“…Bare surface of strangeon star could help in understanding the non-atomic spectra of XDINSs [11]. Additionally, the high binding energy in strangeon matter surface would be necessary for polar gap sparking in pulsar magnetosphere [12,13], being essential to understand radio drifting subpulses (even bi-drifting subpulses [14]) detected, but the binding energy of surface neutron star matter can not high enough to work [15,16]. As gravity-bound body, neutron star's radius decreases as mass increases, and the minimum mass could be order of 0.1M ⊙ .…”

Section: Strangeon Star Identificationmentioning

confidence: 99%

Strangeon Stars

Lu¹,

Xu²

2018

Proceedings of the Workshop on Quarks and Compact Stars 2017 (QCS2017)

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Stable micro-nucleus is 2-flavored (u and d), whereas stable macro-nucleus could be 3-flavored (u, d and s) if the light flavor symmetry restores there. Nucleons are the constituent of a nucleus, while strangeons are named as the constituent of 3-flavored baryonic matter. Gravity-compressed baryonic object created after core-collapse supernova could be strangeon star if the energy scale (∼ 0.5 GeV) cannot be high enough for quark deconfinement and if there occurs 3-flavor symmetry restoration. Strangeon stars are explained here, including their formation and manifestation/identification. Much work, coupled with effective micro-model of strangeon matter, is needed to take advantage of the unique opportunities advanced facilities will provide. KEYWORDS: pulsar: general, dense matter, equation of stateAlthough the state equation of dense matter around nuclear density is a great challenge for physicists, it is usually a thought that strangeness could be relevant to the solution. As noted in the QC-S2014 proceedings [1], such kind of strange matter is conjectured to be strangeon matter, being manifested in the form of compact stars, cosmic rays, and even dark matter. In this contribution, we are focusing on strangeon star, which is a key ingredient of strangeon matter in astrophysics.It is half a century since the first pulsar was discovered, but the real nature of pulsar remains one of the most puzzling problems both in physics and in astronomy. Pulsars are always thought to be neutron stars, but the issue of their real structure is still controversial. Different observations (e.g., the spin period, the measurements of mass and radius) show that the typical density of pulsar-like compact stars could be only a few nuclear density, and the separation between quarks is ∼ 0.5 fm and hence the energy scale is order of ∼ 0.5 GeV according to Heisenberg's uncertainty relation. The pulsar structure is then a problem of non-perturbative QCD (quantum chromo-dynamics), an unsolved issue for fundamental strong interaction at low energy regime ( 1 GeV). Similar to the issue of turbulence, the strong interaction physics at low-energy is still challenging though QCD is mathematically well-defined. In fact, both of "Navier-Stokes Equation" and "Yang-Mills and Mass Gap" are prize problems named by the Clay Mathematical Institute. Hitherto now, no one can derive pulsar structure from ab-initio calculations, nonetheless astrophysicists could speculate phenomenologically.In Fig. 1, we summarize pulsar inner structures (i.e., models) speculators suggest. All of the pulsar structure models fell into four categories: hadron star, quark star, hybrid/mixed star and strangeon star, as are shown in Fig. 1. In the hadron star model, quarks are confined in hadrons, and the hadron liquid is the dominated part of the star. Hadron stars are bounded by gravity, and they must have crusts composed of ions and electrons. A hadron star is called a neutron star if only the nucleon (proton and neutron) degree of freedom is introduced. Conversely, a quark...

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A Model for the Challenging "Bi-drifting" Phenomenon in PSR J0815+09

Cited by 54 publications

References 22 publications

The subpulse modulation properties of pulsars at 21 cm

The subpulse modulation properties of pulsars at 21 cm

Investigation of the bi-drifting subpulses of radio pulsar B1839−04 utilising the open-source data-analysis project PSRSALSA

Strangeon Stars

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